Nordic Road and Transport Research 3-2003

The Leonardo daVinci Bridge

page 18

2 NORDIC ROAD & TRANSPORT RESEARCH NO. 3 2003 3NORDIC ROAD & TRANSPORT RESEARCH NO. 3 2003

Danish Road Institute (DRI)


Avalanche Detection and Alert System for Roads. . . . . . . . . . . . . . . . . . . . 4Public Roads Administration (PRA)

The Valuation of Transport Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Institute of Transport Economics (TØI)

Videoconferencing: Increased Use, Less Travel? . . . . . . . . . . . . . . . . . . . . . 7Institute of Transport Economics (TØI)

Fewer Accidents or Costly Experience? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Institute of Transport Economics (TØI)

Senior Employee Trial Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Institute of Transport Economics (TØI)

Traffic Safety and Disabled Drivers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Institute of Transport Economics (TØI)

Impact Evaluation of PortNet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Technical Research Centre of Finland (VTT), Building and Transport

Comparison of Various Types of Bearing Capacity Equipment . . . . . . . . 12Danish Road Directorate (DRD)

Condition Assessment of Road Equipment Is Unusual . . . . . . . . . . . . . . . 15Swedish National Road and Transport Research Institute (VTI)

SUNflower – Traffic Safety in Three European Countries . . . . . . . . . . . . . 16Swedish National Road and Transport Research Institute (VTI)

The Effect of the Winter Tyre Law on the Use of Tyres and on Accidents. . . 17Swedish National Road and Transport Research Institute (VTI)

Leonardo da Vinci Bridge – a Piece of Applied Art . . . . . . . . . . . . . . . . . . 18Norwegian Public Roads Administration (NPRA)

A N N O TAT E D R E P O R T S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

C O N T E N T S


Avalanche Detection and Alert System for Roads

Background

Vestfirðir in Northwest Iceland is known as an avalanche prone area. The land-scape consists of mountains and fjords with limited amount of flat land. In 1995 two major snow avalanches in the area struck the small villages, Súðavík and Flateyri, and caused a number of deaths and injuries.

Road construction is in general quite difficult in this area and many roads are exposed to avalanches. The 6 km long road along the Óshlíð-hillside between Ísafjörður and Bolungarvík (Figure 1) belongs to this road category. The road was first opened as a track in 1949, rebuilt in the seventies and again in the early eighties.

Observations carried out by the Ice-landic Public Roads Administration have shown that snow avalanches are frequent in 23 tracks or paths in Óshlíð-hillside. In an 11 years period from 1976 to 1986 a total of 948 avalanches that caused road closure were registered in these tracks. In four of the tracks with the highest avalanche frequencies concrete avalanche sheds have been constructed to protect the road. In addition to the

snow avalanches, debris-flow and rock-fall are great threats for car traffic on the road. When these events occur they cause wave motion in the ground close to the tracks. This motion can be moni-tored and used to detect an event. Other methods are also possible, for instance using sound waves or photo technique.An automatic detection and alerting system that can identify the type and extent of a recorded event has several benefits:• During a snow-storm, it informs snow-

clearing foremen and crews about falling avalanches and eventually blocking of the road. It also helps in decision making about when to start snow clearing in the wake of a storm. Based on information from the system it is also possible to close the road for safety reasons. Information about debris-flows or larg rock-fall is also useful.

• It can be used as an indicator of avalanche threat at similar sites in the region where people and civil works are located.

• It can be used for avalanche research. With the system it is possible to time exactly when avalanches fall. By studying weather data and correlating it to the time of avalanche releases it may be easier to understand when an avalanche threat develops

• Finally, by installing a network of detection systems at sites, which are known to have different avalanche sensitivity with respect to weather conditions (wind- and precipitation direction), it is possible to obtain a network of indicators that can be used to declare an avalanche hazard at “matching” sites.

Methodology

To accomplish the objective of obtain-ing an automatic detection and alerting system it was decided to focus on ava-lanche-induced ground vibrations as the main indicator of falling avalanche. A

The road along the Óshlíð-hillside in Vestfirðir in Northwest Iceland is one of the most hazardous roads in Iceland due to rock-fall, debris flows and snow avalanches. A number of avalanche tracks are known in the hillside.

In some of these tracks avalanches fall more frequently than in others. When there is a snow avalanche threat in the hillside many avalanches generally fall from different tracks in a short time period. By monitoring the tracks with the highest avalanche frequency it is likely that one can observe when ava-lanches start falling in the hillside in a snowstorm and then be able to declare an avalanche hazard in the hillside. Based on this knowledge a research project was initiated in February 1996 with the objective of developing an automatic system to detect and analyse avalanches in the Óshlíð-hillside and to send instantly a warning to a control station.

Figure 1. The road along Óshlíð-hillside. The top of the mountain is in 700 m height.

PUBLIC ROADS ADMINISTRATION (PRA)

Authors: Bjarni Bessason, University of Iceland, Gísli Eiríksson, Public Roads Administration, Óðinn Þórarinsson, Univeristy of Iceland.


measurement system similar to what is used when measuring seismic signals was considered appropriate for this purpose. The origin of seismic signal can be quite different. It can be from traffic, rock-fall, debris-flow, and avalanches and even from earthquakes. The main task is there-fore to develop a processing method to analyse and detect a recorded event. For this task it was seen as essential to support the measured data with visual inspections at the site in order to identify and quantify recorded events. Finally, the measured events can be supported and correlated with meteorological data.

Monitoring system

The first measurement system was installed in an avalanche concrete shed in February 1996. The system consisted of data acquisition unit (DAQ) and one three-axial accelerometer. The devices were from Kinemetrics Inc. The accelerometer was located at the top of the inner wall of the shed, i.e. at the hillside side. The DAQ was connected to a modem and measured events could be transferred through the telephone system from Óshlíð to Reykjavik where the system was observed from.

In November 1998 the system was upgraded and expanded to cover three tracks. At the two new tracks the sensors were located on rock outcrop and covered by steel boxes bolted on the rock. In addition to the accelerometers, geophones were also installed. These sensors cost only 1/10 of an accelerometer. When a new event is recorded the new system is capable of automatically alerting the control station in Reykjavik and then to transfer the measured data for the detection process.

All the sensors have a predefined thresh-old. The system only records events when the motion exceeds these thresholds. Data is sampled at 200-Hz. All events are at least 20 s long.

Detection process

Having carried out the measurement for several years, more than thousand events have been recorded. Most of the events are from traffic but a number of other events have been recorded, too. A part of these events have been identified, mainly by field inspections, and stored into a

database. In the database the events are classified into five groups, i.e. events from traffic (trucks), rock-fall, debris-flow, snow avalanches and earthquakes. Within every group the events are size classified as “small”, “medium” and “large”.

For each event “j” in the database, N, representative parameters;

have been determined. These are for instance; peak acceleration, characteristic frequency, bandwidth, duration, power, impact factor, etc.

When a new event is recorded corre-sponding representative parameters, are determined, i.e.;

Then the new event is compared to all the other events in the database by computing the proportional error:

where M is the number of events in the database. The new event is then group classified as the one in the database, which gives the lowest proportional error, Ej. This is a kind of a “nearest neighbour method”. Finally, the event is size classified, i.e. “small”, “medium” or “large”, with respect to the group it belongs to. In Figure 2, time

histories and corresponding power spectral densities from three different recorded events are shown. Note the difference in ampliutde, frequency content and duration.

The results of the detection process are published in a home page on the Internet and an alert message is sent out via E-mail to key personnel. On the Internet the time and location (no of track) of recorded event is presented as well as some representative parameters. The final step in showing the results of the group and size classification is still missing but it will be implemented in the detection process this year.

Conclusions and summary

The research project was initiated in Feb-ruary 1996 and it is still going on. The operation of measurement equipment has been stable and satisfactory although oper-ated in severe environmental conditions. A lot of data has been obtained. Most of the data is from the concrete shed, but less data has been obtained for the other two tracks were the sensors are located on rock outcrop. More data in the database will improve the reliability of the detection process. The Internet home page has been operational from 1997. It takes about two minutes to update the home page in the wake of a recorded event.

Figure 2. Time series and below corresponding power spectrum for three recordedevents in Óshlíð: a) Snow avalanche, b) Debris flow c) Passing truck.

PUBLIC ROADS ADMINISTRATION (PRA)


INSTITUTE OF TRANSPORT ECONOMICS (TØI)

Transport safety is valued very differ-ently in various countries. This may be explained in part by circumstances such as differences in definition, the compo-nents that are included, income differ-ences, differences in culture and tastes and the assessment year.

In 2002 the Research Council of Norway initiated a new research programme on risk and safety in transport (RISIT). As an introduction to this programme it was decided to prepare state-of-the-art reviews of selected topics. One of these topics is “The valuation of transport safety”, which is the subject of this report.

The most important use of valuations of transport safety is in cost-benefit analy-ses (CBAs). A cost-benefit analysis is a method that provides the basis for a sys-tematic and consistent treatment of dif-ferent impacts of measures/projects. The theoretical basis of CBAs is economic welfare theory. For a CBA to provide a basis for decision making consistent with the assumptions on which such analyses are based, non-market goods that are included must be valued with correct rela-tive prices, and the welfare effects must be based on people’s preferences (meas-ured by their willingness to pay).

There are large variations in valuations of transport safety in various countries’ cost-benefit analyses. Costs related to traffic accidents are often divided into the following three components: direct costs, such as damage to vehicles and property, the costs of emergency services, medical treatment, burial etc., lost production for the society resulting from injury or death and human costs, in the form of pain, suf-fering and grief.

The methods for estimating the value of human life can be divided into three main categories: human capital methods (output methods), which find net or gross lost production due to injuries or death, plus any direct costs, revealed preference methods, which are based on individuals’ preferences in real markets such as insur-ance markets or compensation from law-suits, or politicians’ preferences implicitly

revealed through political decisions, and stated preference methods, which are based on individuals’ preferences in hypothetical markets.

Not all countries’ cost estimates include human costs, and there are also differ-ences in the components that are included in direct costs and how lost production is calculated in various countries. Such differences give rise to variations in the cost estimates, making it difficult to make comparisons between countries. Nor is comparison easier when the methods used to calculate costs partly overlap, poten-tially resulting in double counting.

Figure 1 shows that transport safety is valued very differently in various coun-tries. This may be explained in part by circumstances such as differences in defi-nition, the components that are included, income differences, differences in culture and tastes and the assessment year. But the most important explanatory variables are whether human costs are included, and if so, whether these are based on people’s preferences or not, and meth-odological problems that give rise to great uncertainty in the valuation estimates. It is customary to use the same valuation in all modes of transport, and such valuations are largely based on valuation studies done for road transport.

The Valuation of Transport Safety

Figure 1: Official valuations of a traffic fatality in various countries ranked in ascending order. Unit: purchasing-power-parity-adjusted 1999 USD. Source: TØI report 634/2003

Title: The valuation of transport safety. A state-of-the-art review for the RISIT programme Author: Kjartan SælensmindeSeries: TØI Report 634/2003Language: Norwegian with English summary. The summary is available on http://www.toi.no/program/program.asp?id=113317



Videoconferencing: Increased Use, Less Travel?

During recent years sales of videocon-ferencing equipment have increased rapidly in Norway and elsewhere. However, videoconferencing has so far only to a minor degree substituted busi-ness travel.

An important task within transport plan-ning is to forecast the possible impacts of videoconferencing on business travel. The aim of a recent project has been to examine use of and attitudes towards videoconferencing in Norwegian industry and commerce, and how videoconferenc-ing changes travel patterns and collabora-tion between businesses.

Data were collected via a postal survey among financial directors in 563 enter-prises, of whom 164 used videoconfer-encing. The sample was drawn from the same industries as a previous study in 1998.

Attitudes towards videoconferencing

Videoconferencing usage has increased. 29 per cent of the enterprises in the present survey report use, compared to 20 per cent in 1998. These figures are not

representative for Norwegian enterprises in general, but an effect of the sample partly being drawn from industries known to be in the front with respect to videocon-ferencing usage.

Results show overall positive attitudes towards videoconferencing. This also applies to firms that currently do not make use of this technology. Compared to 1998 results, fewer state that the technology for videoconferencing is inferior. With respect to future diffusion, this is clearly positive. On the other hand, more regard costs to be high. Most likely, this is due to the current depression in the economy.

Many consider travelling a burden, both in respect of the working situation and family life. However, these negative aspects of business travel conflicts with the business community’s need for exter-nal contact. Three of four financial direc-tors actually consider personal contact to be irreplaceable.

Uniform use

During recent years, mid-sized enterprises (20–100 employees) have increased their use of videoconferencing significantly, and become a more important user

group. To some degree, this has changed videoconferencing usage. For example, videoconferencing is more often being used in customer contact. However, the overall picture is the same as in 1998 – videoconferencing usage is rather unde-veloped in the sense that it is used by a relatively small number of people within the organisation, and for a restricted range of purposes and contact points. Daily use is largely characterised by internal com-pany meetings where routine information is exchanged. Managers are the largest user group.

Minor substitution effects

The interaction between videoconferenc-ing and transport has been an important issue within transportation research since the introduction of the technology in the 1970s. Recent research has shown that substitution effects are questionable, and that ICT (Information and Communica-tion Technology) in some situations can also generate travel.

Videoconferencing has so far only to a minor degree substituted business travel in these firms. Results from the present study indicate that about 40 per cent of video-conferencing users have managed to substitute some travel, but only some 10 per cent have experienced substantial replacement. A few users report that video-conferencing has in fact generated travel within their company, reducing the net substitution effect. Yet, generation of travel due to videoconferencing is far less than the substitution effect.

Substitution is somewhat stronger now than five years ago. Again, this is most likely due to the depression in the economy.

Results from the present study indicate that about 40 percent of videoconferencing users have managed to substitute some travelling, but only some 10 per cent have experienced substantial replacement.

Title: Videoconferencing in Norwegian industry and commerce: Increased use, less travel?Authors: Jon Martin Denstadli og Tom Erik JulsrudSeries: TØI report 670/2003Language: Norwegian with English summary.Summary: http://www.toi.no/program/program.asp?id=291665

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and 48 per cent of the non-members stated that they drove at legal speeds in built-up areas. In 2002 54 per cent of both groups claimed that they drove at legal speeds, i.e. the difference in complying with the speed limit existing in 2000 had disappeared. This is the opposite of the intended effect of Driver2000.

As no long-term effect on driver seat-belt wearing or compliance with speed limits has been proven, there is reason to believe that Driver2000 had no significant long-term effect on road accidents or injuries, even if the campaign caught the attention of drivers and recruited a rela-tively large number of members.

Conclusion

A major problem with the application of the positive means was the control of compliance with the contract – did the members actually use theirs seat belts and comply with speed limits? The only thing controlled was that the winners of the monthly car lottery actually had the Driver2000 sticker on their cars. To have a fair chance to influence the road behav-iour of the members, the Driver2000 should have included some kind of moni-toring of members’ speed and seat-belt wearing.

To reduce the number of accidents by information campaigns, the extent of

The members of “Driver2000” attached a sticker to the rear window of the car to expose their membership.

Title: Fewer accidents or costly experi-ence? Evaluation of the campaign “Driver 2000”Authors: Terje Assum and Aslak FyhriSeries: TØI report 661/2003Language: Language: Norwegian with English summarySummary: http://www.toi.no/program/program.asp?id=267265

Fewer Accidents or Costly Experience?The Norwegian traffic safety campaign “Driver2000” managed to recruit 140 000 drivers as members, but the evalu-tion shows no indication of long-term effects on the driver behaviour focussed, i.e. seat-belt wearing and compliance with speed limits.

Accident reduction was to be achieved through rewards and a contract com-mitting the members of Driver2000 to respect the speed limits and to use their seat belts. Moreover, a Driver2000 sticker should be attached to the rear window of the car to show that the driver had signed the contract. The primary reward was a free monthly lottery of cars and other prizes. The members, having signed the contract, should be persuaded to respect the speed limits, use their seat belts and be responsible in road traffic in general.

Driver2000 was organized as a foun-dation in collaboration between private, industry and the public authorities. Important partners were the Norwegian Automobile Importers’ Association (B.I.L), the Public Roads Authorities and the Norwegian Society for Road Safety (Trygg Trafikk). Driver2000 was planned to go on for three years, 2000–2002, but the grants for the campaign were reduced or stopped during fall 2001. Conse-quently the campaign activities came to an end. The final number of members was 140 000 by fall 2001 or an estimated 5 per cent of Norwegian car drivers.

“Driver2000” reached their prime target groups, i.e. young men who drive exten-sively, the drivers who are most exposed to road accidents.

The Institute of Transport Economics (TØI) was assigned to evaluate the cam-paign.

Results

In 2000, 94 per cent of the members stated that they always wore a seat belt when driving in built-up areas compared to 84 per cent of the non-members. In 2002 there was no significant difference in seat-belt wearing between members and non-members.

In 2000, 61 per cent of the members

risky behaviour has to be reduced. To achieve this modification of behaviour the combination of information and increased police surveillance is generally recommended. Moreover, the behav-ioural modifications wanted should be expressed clearly. Instead of surveillance the Driver2000 applied positive means as motivation. Such means as rewarding right behaviour and commitment to right behaviour through a signed contract have not been extensively tested in road safety work. Consequently, it was difficult to anticipate the results. Another condition to campaign success is the actual carrying out of the campaign activities. As men-tioned, the grants for Driver2000 were stopped, and the campaign activities came to an end after 1 1⁄2 years instead of 3 years as planned. It is impossible to say what results could have been achieved if the campaign activities had been continued throughout the planned period.




The major public transport operator in Oslo has carried out a project where a group of senior employees worked less, in order to lessen their amount of sick days. These employees had originally more sick days than the average employee, caused by serious health problems. This report shows results from the project. We report results on goal achievement, the par-ticipants’ views on the project and how the project has affected the participants’ quality of life. The project is concidered successful because of a high level of goal achievement, and because participants report a better quality of life as a result of the project.

The sickness absence statistics for the target group changed radically during the trial period. The year before the trial period the target group had a substantially higher sickness absence than the average for the employees of the public transport operator. During the test period sickness absence was reduced considerably.

Interviews show that employment to a large extent has effects for the private lives of the senior employees. The Senior Employee Trial Scheme has allowed the participants to get valuable rest. On this background the participants reports that the effects on their private lives are less-ened, compared to the situation before the introduction of the scheme.

The participants report of a higher degree of energy to live a fulfilling life after working hours, and an improved ability to care for family and friends. All

in all, the participants feel that their qual-ity of life has improved greatly as a result of the trial scheme.

The public transport operator is also given credit for designing a well balanced project when it comes to the needs of their employees.

Title: Evaluation of the Senior Employee Trial Scheme in AS Oslo SporveierAuthor: Trine HagenSeries: TØI report 627/2003.Language: Norwegian with English summary.

During the test period sickness absence was reduced considerably.

Senior Employee Trial Scheme

Traffic Safety and Disabled DriversVarious adaptations of cars for disabled drivers are discussed on the basis of theoretical analyses of the driving task as related to driver information processing and information needs. Some adaptations may create problems possibly increasing the risk of dangerous traffic situations. Performing several control operations e.g. with one hand, the most extreme example being a 4-way joystick, may produce interference between braking,

accelerator and steering functions. An analysis of crashes reported to insurance companies for a sample of adapted cars does not indicate elevated crash involve-ment. This finding is possibly explained by drivers compensating for a difficult driving task by driving more cautiously, slowing down, concentrating more on the traffic, and/or avoiding difficult driving conditions. There is a need for further studies to investigate differences in risk

between various technical solutions for adapted cars.

Title: Traffic safety of adapted cars for disabled driversAuthors: Fridulv Sagberg, Alf Glad, Astrid Helene Amundsen, Kari Midtland,Series: TØI report 626/2003.Language: Norwegian with English summary.


Figure 1. PortNet system operating principle.

TECHNICAL RESEARCH CENTRE OF FINLAND (VTT), BUILDING AND TRANSPORT

The objectives of this evaluation project were first of all to evaluate the impacts of the PortNet system on the economy, environment and information society – in sum, on common Finnish policy goals. The evaluation also included quantitative cost-benefit analysis and qualitative anal-ysis of other aspects, such as organisation, legal aspects and technical issues, to name but a few. Secondly, the objective was to evaluate the usefulness of the Evaluation Guidelines. Finally, the evaluation was expected to produce a sound long-term development strategy and development needs list for the PortNet system. This would then serve the commercial and other aims of the PortNet stakeholder community, which includes ports, Finnish Maritime Administration (FMA), Finnish Customs Administration (FCA) and some major shipping line companies, as well as brokers and agents.

Step-by-step evaluation

It became evident that the Evaluation Guidelines could not be followed “all the way through” because many impacts were so difficult to assess. On the other hand, the aim of the Guidelines is naturally to

provide an evaluation framework that has to be applied on a case-to-case basis using common sense. For this purpose, the Guidelines proved to be extremely handy.

The following impacts were evaluated:- economic impacts that were given a monetary value- qualitative impacts- evaluation of the organisation model of PortNet- pricing principles- evaluation of technical implementation and HMI (human-machine interface)- evaluation from transport policy and “infosoc” perspective- other potential impacts.

The cost-benefit analysis was per-formed using a 5 per cent annual, nominal discounting rate and two time periods, 1990–2010 (from the very beginning of PortNet development) and 1998–2010 (from the beginning of current version development). The basic year (year 0) for calculations was 2002. Another round of calculations was performed using the same starting points but extending the future projections to 2015. Altogether four time periods (1990–2010, 1998–2010, 1998–2010 and 1998–2015) were analysed because the evaluation group wanted to see what the actual costs and benefits would be when one considers the whole evolution process of this kind of ITS application and includes the very first phase investments and development costs.

Evaluation results

The benefits and costs of PortNet are strongly dependent on the amount of active use, i.e. penetration of usage, and number of vessel calls in Finnish har-bours. The more ship calls there are and the more harbours, shipping lines and agents use PortNet, the more benefits will of course be realised.

This is the first lesson of impact evalu-ation: with high levels of penetration (users, customers, and so forth), benefits start to accrue. In the case of PortNet, the critical level of penetration was around

Finland’s most prominent maritime ITS application, PortNet, showed prof-itability though only part of the actual benefits could be included in calcula-tions. However, it was concluded that few business organisations would invest in similar systems even though they would benefit from it.

The revised Finnish ITS Evaluation Guidelines were issued last year. This evaluation tool was used in the evaluation of PortNet. PortNet is a maritime opera-tions service portal that allows authorities and business organisations to exchange information electronically, using com-monly agreed data formats.

The following functions/services are available through PortNet:- ship timetables, including preliminary and advance notices- all cargo information, including hazardous materials and dangerous goods- statistical ship data on ships that have previously visited Finland- service orders such as piloting and towing- data on paid fairway and exemptions- various dropdown tables and statistics.

Impact Evaluation of PortNet


TECHNICAL RESEARCH CENTRE OF FINLAND (VTT), BUILDING AND TRANSPORT

When calculating benefit-cost rations, even in the “worst case” (1992–2010) example the benefit-cost ratio is more than 2, which certainly indicates profit-ability. In the “best case”, the B/C ratio exceeds 3.

The benefits and costs were also calcu-lated for different parties in order to see who, at the end of the day, are the net ben-eficiaries and who are the net payers of the system. What was clear was that compa-nies, i.e. the private sector, are those who benefit the most. Ports and FMA are the payers of the system. Ports’ figures result from the fact that ports granted reductions for fairway fees for those companies who used PortNet for vessel and cargo infor-mation exchange. These reductions still burden the ports’ key ratios, though the reductions will be aborted from the begin-ning of 2003. From thereon, the ports will join the beneficiaries.

Somebody will always have to pay the start-up costs for any system or service. If we wait for the private sector to do so, we may have to wait for a considerably longer time. Public organisations can work as an efficient catalyst in the start-up phases of beneficial systems.

Transport policies are supported

The use of PortNet will enhance maritime transport safety and reduce environ-mental damage risk (hazardous material

50 per cent assuming normal growth in vessel traffic. With no growth assumption the “break-even” penetration would have to be even higher.

Figure 2. PortNet net benefits (blue line) after investments (green columns) and operating costs of the system (dashed blue line).

Title: PortNet Impact EvaluationSeries: FITS Publications 15/2003Authors: Raine Hautala, Pekka Lev-iäkangas, Risto Kulmala, Seppo Auvinen, and Robin BerglundLanguage: EnglishReport can be downloaded from: http://www.vtt.fi/rte/projects/fits/julkaisut/hanke8/portnet_english.pdf

information, vessel safety information, safety record statistics, etc.). PortNet is everything that an information society represents – sharing common data, build-ing efficient multi-user and multi-purpose information sharing networks, and so forth. The service level of the transport system is improved thanks to more effi-cient information exchange.

The impact on supply chains was evalu-ated based on estimates on timesaving and volumes of foreign trade. If every transport unit, whatever the unit, could save 30 minutes at only one point of the chain, this would yield considerable sav-ings for the whole society. However, we have to remember that this a theoretical aggregate level benefit is not necessarily realised nor recognised at firm level, be it shipping lines, agents, container opera-tors, truckers, railway operators, etc. It is not something that these firms would be ready to invest in.

In sum ...

We can conclude from the PortNet evalu-ation that the system is profitable in a socioeconomic sense, even if only part

of the benefits could be counted in. The costs, however, were included as far as they were known.

PortNet is a concept of public-private-partnership that combines many interests. Evidently public activity and support are needed if these kinds of “multi-player” and “multi-benefit” systems are to be deployed. Companies seek shareholder value, and this interest is so strong that it practically hinders companies from investing in systems that produce sector benefits, even if these companies would in the end benefit themselves. Wide impact investments are very hard to justify to shareholders. This problem is particularly relevant in the logistics industry, which is dominated by multiple, private and com-peting companies. Public organisations, such as FMA in Finland, have to step in and initiate, assist and promote invest-ments like PortNet.


ment, the Danish Road Institute carried out a test to examine whether it would be possible to replace the plate loading equipment with the ordinary Falling Weight Deflectometer (FWD) or possibly with a portable FWD.

Five different equipments compared

The following measuring equipment was used in the test:• Static plate loading equipment (Road Directorate)• FWD (Road Directorate)• Portable FWD:

– Loadman (Finland, represented by AL-Engineering)– Keros Prima 100 (Denmark, represented by Keros)– Zorn ZFG 2000 (Germany, represented by Gravquick A/S, Denmark).As a supplement to the field trials,

compaction control was carried out in situ with a nuclear density gauge. Reference tests were carried out in the laboratory.

The static plate loading test and the FWD test are well-known, so only the portable FWDs require special attention..

Portable FWDs

Portable FWD is a common name for portable equipment, which functions by means of a weight which falls from a given height onto a load plate of given size. The load is either known or measured by means of a load cell and the resulting vertical deflection in the middle of the load plate is registered by a geophone or an accelerometer placed in or on top of the load plate. The purpose of the portable FWD is to offer simple and cheap measurements of bearing capacity of road pavements. The three portable FWDs, which were used for the test are shown in Figure 1.

Comparison of Various Types of Bearing Capacity EquipmentThis article has been specially written for Nordic Road & Transport Research by Dr. Gregers Hildebrand. For further informa-tion, please write to [email protected].

The Danish Road Institute has com-pared results of bearing capacity meas-urements on granular base material by three different tests: static plate loading test, Falling Weight Deflectometer and the portable FWD. The experiment shows very good correlation between the results from static plate loading tests and the Falling Weight Deflectometer. Three different portable FWDs show promis-ing results, but this type of equipment has its greatest potential when measur-ing soil and granular subbase and using it in places where it is not possible to use a Falling Weight Deflectometer.

Construction of roads requires informa-tion on road materials before, during and after completion of the work. Thorough knowledge of the road materials in the planning phase is a prerequisite to plan a good project, whereas material data during the actual construction of the road is important for the correct handling of the materials and thus for obtaining the optimum quality of the construction. After the opening of the road, information about the condition of the road materials is important to make it possible to monitor the deterioration of the road and thus plan necessary maintenance.

When planning a road construction the values for the stiffness of the road materials (E-modulus) is pre-determined. These E-moduli must be verified in situ in connection with construction work. Tra-ditionally, the Road Directorate has used static plate loading tests to evaluate the bearing capacity of unbound materials in the construction phase of a road. Since the equipment used for this test must now be renovated or replaced with other equip-

Advantages of portable FWDs are the following:- relatively cheap- easy to transport- easy use- measurements are quick to perform- simple data analysis, which gives quick results.

The portable FWD is well suited for use in places which cannot or only with dif-ficulty can be reached with a vehicle due to insufficient bearing capacity (i.e. soft materials) or insufficient space (utility cuts and excavations). The equipment is well suited for control purposes at build-ing sites, where the equipment can be available and be used frequently without requiring special assistance.

The most important hindrance for the success of the portable FWD in Den-mark is presumably that Road Standards and other standards do not require proof of bearing capacity but instead proof of compaction. For that purpose, non-destructive equipment is available such as the nuclear density gauge. However, the advantage of the portable FWD is that contrary to the nuclear density gauge, the FWD does not use radioactive material which requires special education by its users and which makes it difficult to take on trips. Furthermore, the portable FWD can be used to measure on slag. However,

DANISH ROAD DIRECTORATE (DRD)

Figure 1. The three portable FWDs, which were used for the test. From left: Zorn, Load-man and Keros.


the distribution of the measuring points. The FWD and the portable FWD are quick equipment and could therefore measure in all 40 cross sections whereas the plate loading equipment only meas-ured in every second cross section in order to be able to complete the meas-urements in one day. The placing in the cross section of the individual pieces of equipment changed for each cross section so that any difference across the stretch should not be confused with a difference between measuring equipments. The water content of the gravel layer was 5–6 per cent in the entire section, whereas the degree of compaction varied between 96 and 101 percent. It appeared that tracks B and D were compacted more evenly than the other tracks.

Calculated values of the surface module E0

The surface modulus E0 was calculated for each equipment in the load centre by means of equation 1. Based on the test-

this article concentrates on the use of the portable FWD for determination of E-moduli (i.e. bearing capacity).

Test for comparison on equipment

A section, approximately 400 m long with a width of 7 meters and 1 meter on each side for a bicycle track was used for the test. The road was constructed at ground level on a base of moraine sand (very gravelly), and the construction consists of approximately 30 cm subbase and approximately 25 cm granular base mate-rial. The tests were carried out on the base layer.

The section was divided into 40 cross sections with a length of approximately 7.5 meters. Each cross section consisted of 4–5 measuring points with a distance of approximately 1 meter. Figure 2 shows


Figure 2. The distribution of measuring points on the test.

ing results obtained by the measurements according to Figure 2, E0 in the load centre is obtained as follows:where is Poissons ratio, a is the radius in the load area, d is the deflection and 0 is the contact pressure. When calculating E0 a Poissons ratio of 0.5 was assumed. This value was chosen since some types of equipment use this value and auto-matically calculate E0 in this manner.

Unbound materials such as gravel and sand often have a Poissons ratio of 0.35 – 0.45. Since the purpose was to compare various types of equipment, the value of was not of any practical importance as long as it was identical for all types of equipment. Figure 3 shows a comparison of the surface modules with the 5 differ-ent types of equipment at load levels of approximately 200 kPa and with a load plate with a diameter of 300 mm.Figure 3 shows a good correlation between the E0-values from the plate loading equipment and the FWD. There is a certain correlation between plate loading and FWD on the one hand and the portable FWDs of Keros and Load-man on the other hand. The Zorn portable FWD gives considerably lower E0-values

Figure 3. Comparison of surface moduli determined with five different types of equipment. The load level should be approximately 200 kPa and a plate diam-eter of 300 mm. After the tests, Keros discovered that their device had been incorrectly calibrated. The correct calibration would increase the values for E0 for the Keros device by 18 per cent.

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than the other types of equipment, and the equipment has the lowest variation on the test section. Since the various types of equipment measured in various measur-ing tracks, a certain variation must be expected between the E0-values in spe-cific measuring stations, wheras the aver-age for the stretch ought to be identical for all five types of equipment.

Table 1 shows averages and standard deviations for the surface modulus in tracks B, C, and D, which had the most uniform bearing capacity.

Conclusion

The primary purpose of the test was to examine, to which extent the current equipment for static plate loading tests can be replaced by a FWD. Based on calculations of the modulus E0 in the load centre it appears that there is a very good and direct correlation between the results from the two pieces of equipment. A final evaluation must however be based on tests from various other base materials, and at the same time the test must be based on determination of the E-moduli for base courses, sub-base layers and subgrade.

The comparative tests showed that the FWD gives surface moduli which are almost identical to those obtained by the plate loading equipment, whereas the three portable FWD give surface moduli, which to some or at least to a limited extent resemble the results obtained by the plate loading equipment. The test show that Keros and to a lesser degree Loadman are in agreement with the results from the plate loading equipment and FWD. The surface moduli from Zorn’s portable FWD are considerably

lower than those measured with the other equipment.

On the basis of the tests carried out the Road Directorate predicts that portable FWDs will not be used for measurement on granular base courses. In this situa-tion the FWD gives results, which can be compared to the reference equipment, the plate loading equipment. The FWD car-ries out the measurements at least as fast as a portable FWD, and the FWD gives more measurement results. The Road Directorate, however, predicts consider-able use of the portable FWD for meas-urements on subgrade soils and sub-base materials as well as in places where it is not possible to use the FWD.

In response to a very large interest in portable FWDs, a national Danish user group for portable FWDs is about to be formed. Participants include manufactur-ers, contractors, consulting engineers and road authorities.

Equipment E0-average

(MPa)

Standard deviation- E0

(MPa)

Standard deviation- E0

(% of E0-average)Loadman 97 12.8 13.2Zorn 60 5.7 9.4Keros 118 19.9 17FWD 149 16.4 11Static plate loading 145 11.0 7.6

Table 1. Average and spread for E0 in the measuring track B, C, D.

The full report of the tests can be found on the homepage of the Road Directorate:http://www.vd.dk/pdf/eksnot16.pdf


Visit our web site: www.vti.se/nordic

Visit our web site: www.vti.se/nordic

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New Year

2004!

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2004!


SWEDISH NATIONAL ROAD AND TRANSPORT RESEARCH INSTITUTE (VTI)

parameter. Since such measurement costs time and money, it is often impossible to measure all equipment of the type con-cerned, and it is necessary to make meas-urements on a sample of the population. Condition assessment therefore usually requires not only a physical measuring method but also a sampling method.

A survey of the literature relating to road equipment shows that such stud-ies are rare. There may be a number of reasons: some equipment requires only a simple inspection and this can therefore be made for all equipment of this type at frequent intervals. There is therefore no need to sample in time, to sample equipment or to use a physical measuring

A survey of literature relating to con-dition assessment of road equipment shows that such studies are rare. One reason for this is often lack of practical measuring methods.

Road equipment is used to improve traf-fic safety and traffickability on roads and also to control and guide traffic. Once an investment has been made in road equipment, it is important to ensure by

appropriate maintenance measures that its function is retained. The time when these measures are to be employed can be deter-mined by condition assessment of the function. Such assessment may be made by visual inspection or a simple physical measurement. This report gives details of a survey of literature concerning measure-ments used in condition assessment and methods which may be suitable for use in such measurements.

Road lighting and safety barriers

Condition assessment of the function of road equipment in most cases entails physical measurement of some relevant

Condition Assessment of Road Equipment Is Unusual

method. Another reason may be that there are no easy-to-use measuring instruments available.

As far as road lighting is concerned, no reference to condition assessment of the lighting function can be found in the lit-erature. The reason for this is obvious: the function of road lighting is best described by carriageway luminance, and this is dif-ficult to measure. An alternative property that is easier to measure is illuminance. This measurement may however be sen-sitive to disturbance by nearby vehicle lights, and measurement at the time of low traffic volumes is therefore necessary in practice. There is however a Swedish study on the condition assessment of lighting columns. This study condemned 34 per cent of the columns, mostly because they were too near the carriage-way in contravention of the regulations.

Condition assessments of safety barri-ers and noise barriers have been carried out in USA and Sweden. The American study relates to noise barriers which were visually inspected. The conclusion was that all types of noise barriers may be con-sidered to be maintenance free for twenty years after erection. In Sweden a visual inspection was made of safety barriers on roads which had been sampled. The results showed that 7 per cent of safety

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A lamppost that is twisted 1800.

Worn-out road markings.



barriers at the sides of Swedish roads did not comply with regulations.

Road signs and carriageway markings

Road signs are the type of road equipment which has been investigated in most stud-ies. In several studies a relationship was sought between the age of the reflector-ised surface and retroreflection. Swedish, German, American and Australian stud-ies give similar results: ten years after the erection of the sign, the reflectorised surface has retained 70–98 per cent of retroreflectivity. Measurements were made with different types of hand-held instruments, which may be impractical; it is difficult to reach up to the sign. Vehicle mounted measuring methods are needed.

Instruments – both vehicle mounted and portable ones – are available on the market for physical measurements on carriageway markings. In spite of this, condition assessments of carriageway markings have been made only in the Nordic countries, and mainly in Sweden. These studies refer to the retroreflective

properties of carriageway markings and show that most carriageway markings in Sweden do not satisfy the requirements in Swedish regulations. An American report on conditions assessment of carriageway reflectors describes measurements with a portable instrument.

Traffic signals

It is difficult to make physical measure-ments of the function of traffic signals, and there are no commercial instruments available. There are consequently no references to condition assessment in the literature. The introduction of automatic monitoring of traffic signal installations has also reduced the need for condition assessment.

The conclusion of this study of the literature is that development of methods for condition assessment of road equip-ment should focus on- development of a vehicle mounted method for physical measurements on lighting installations- development of a vehicle mounted

Title: Condition assessment of road equipment. State of the artAuthor: Sven-Olof LundkvistSeries: VTI rapport 471Language: Swedish with English summaryThe report is also available as a pdf file on vti.se under Reports

SUNflower – Traffic Safety in Three European CountriesAlthough the traffic safety records of Sweden, the United Kingdom and the Netherlands are the best among the countries of the European Union, their accident rates are still unacceptably high. New ways for further improvement have to be, and are being, sought to further reduce casualties in these countries. Interestingly, the strategies, which have produced the relatively good results, are quite different in these three countries. So, the question arose what they exactly worked with when coping with the traffic safety problem. And further, if specific beneficial patterns or underlying concepts can be determined, is it then possible to interchange them.

A better insight into the development of policies and programmes in these countries might conceivably identify key factors, which could further improve current safety practice in each of them.

The methodology of the study has been designed in such a way that it can be used as a basis for comparative studies among other member states.

The study was performed by a team of researchers from three institutes: VTI, the Transport Research Laboratory, United Kingdom, and the SWOV Institute for Road Safety Research, the Netherlands.

Moreover, it might offer guidance for remedial action in other countries of the European Union, applicant states, and other countries as well. Learning from each other and putting that learning into practice, is an indispensable part of gain-ing maximum improvement in safety. Such improvement should be given high priority, considering that each year more than 40,000 citizens of the European Union meet premature death on the roads. Moreover, ideas are in progress to come up with a quantitative target to reduce the number of fatalities by 50 per cent in the European Union in ten years’ time.

In this context, a study was carried out to assess the background to the safety strate-gies of Sweden, the United Kingdom and the Netherlands: the SUN countries. The results of this study are of special value in the progress of development of the safety programmes of the three countries.

Title: SUNflower: A comparative study of the development of road safety in Sweden, the United Kingdom, and the NetherlandsAuthors: Matthjis Koornstra (SWOV), David Lynam (TRL), Göran Nilsson (VTI), Piet Noordzij (SWOV), Hans Erik Petters-son (VTI), Fred Wegman (SWOV) and Peter Wouters (SWOV)Language: English An electronic version can be down-loaded at www.vti.se under Reports

method for physical measurements of the function of carriageway markings- development and adaptation of sampling methods for road lighting and carriage-way markings.

Finally, it is emphasised that methods for condition assessment must be easy to use and suitable for personnel who have no knowledge of advanced measuring techniques.



The Effect of the Winter Tyre Law on the Use of Tyres and on AccidentsThe survey of tyre use in Östergötland county, southern Sweden, shows that the proportion of studded tyres increased from ca 75 per cent before the introduc-tion of the Law to ca 80 per cent after its introduction. The proportion of winter tyres without studs increased from ca 15 to ca 20 per cent. The use of summer tyres was cut by half during the 1990s even before the requirement concerning winter tyres came into force, i.e. people expected the requirement and adjusted accordingly. The term ‘winter tyres’ in the Winter Tyre Law refers to winter tyres both with and without studs.

Title: The effect of the Winter Tyre Law on the use of tyres and on accidentsAuthors: Gudrun Öberg, Hans Velin & Mats WiklundSeries: VTI rapport 479Language: Swedish with English summaryThe report is also available as a pdf file on vti.se under Reports

In the summer of 1999 the Swedish Government promulgated a Decree according to which cars, light lorries and buses, of a total weight not exceed-ing 3.5 tonnes, shall during the period 1 December–31 March, when travelling on a road, be fitted with winter tyres or similar equipment when winter road conditions prevail. The Law came into force on 1 December 1999. This Decree was followed by an Order which specifies the period when studded tyres shall not be used; this period is 1 May to 30 Septem-ber. One further Order was issued which requires a least tread depth of 3 mm under winter road conditions during the period 1 December to 31 March, as against the previous requirement of 1.6 mm through-out the year.

When the requirement concerning winter tyres for light vehicles had been in force for two winters, the Swedish National Road Administration wanted to have a preliminary indication of the way tyre use has changed and whether there have been any improvements in traffic safety. VTI was commissioned to carry out this investigation.

The study of accidents shows a steep reduction in personal injury accidents with fatalities and severe injuries between the winters before (97/98 and 98/99) and the winters after (99/00 and 00/01) when winter road conditions prevail. An

estimate of the effect on these police-reported accidents shows that they had decreased by 11 or 14 per cent depending on whether it is assumed that winter tyres also have a significance on the accident effect on roads free from snow and ice. When all road conditions are considered, these injury accidents decrease by 8 per cent over the period 1 December–31 March. These decreases are not statisti-cally verified.

For all road conditions, the following change occurred from the before to the after period.

Table 1 shows a reduction in the number of accidents with different degrees of severity in all road conditions. None of the decreases has been statistically veri-fied.

Table 1. Effect on police reported accidents from the before-winters to the after-win-ters, for all road conditions.

Degree of severity Effect 95% confidence intervalLower Upper

Accidents (fatalities, severe and slight injuries) -2 % -10 % +7 %Accidents (fatalities and severe injuries) -8 % -22 % +8 %Accidents (fatalities) -3 % -35 % +43 %

Table 2. The effect on police reported accidents from the before-winters to the after-winters when winter road conditions prevail according to information on the police accident report form, on the assumption that the Tyre Law has an influence on the accident outcome even on roads free from snow and ice.

Degree of severity Effect 95 % confidence intervalLower Upper

Accidents (fatalities, severe and slight injuries) -12 % -23 % +0 %Accidents (fatalities and severe injuries) -14 % -33 % +9 %Accidents (fatalities) -14 % -55 % +58 %

Table 2 shows a large reduction, not sta-tistically verified, in personal injury acci-dents on roads with ice/snow cover from the before-winters to the after-winters.

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NORWEGIAN PUBLIC ROADS ADMINISTRATION (NPRA)

During an exhibition of the works of Leonardo da Vinci the Norwegian artist, Vebjørn Sand, got the idea of translating the original bridge concept of Leon-ardo into a smaller, modern pedestrian bridge. Leonardo’s original concept was to build an enormous stone bridge across the Golden Horn, a horn-shaped estuary dividing the European Istanbul. With its free span of about 234 metres and a vertical clearance of about 40 metres, the structure would have been one of the great wonders of the world if it had been built.

Leonardo’s original bridge concept

The concept dates back to around 1502 as sultan Bajazet II considered replac-ing a floating timber bridge across the Golden Horn with a more permanent one. In a letter, Leonardo made a proposal for a stone bridge and description of how

to construct the bridge. In combination with a small sketch showing plan and elevation, it is possible to get an idea of the construction principles. Investiga-tions made in our days conclude that the construction of the bridge would have been technically feasible. However, the sultan probably did not dare to carry out the project or he considered it too expen-sive – nevertheless, the bridge was never built.

The article is written by Tormod Dyken, Norwegian Public Roads Administration, Bridge Departmente-mail: [email protected] of bridge: Jiri Havran

In the Municipality of Ås, about 20 kilometres outside Oslo, a rather special structure is situated, being both a foot-bridge and a sculpture. It makes it pos-sible for pedestrians and bikers to cross the main road E18 in a safe way, as well as it offers the car drivers a pleas-ant view of beautifully shaped arches. The bridge appears more as the product of an artist than that of an engineer, although much engineering effort and creativity were required in order to materialize the concept.

Leonardo da Vinci Bridge – a Piece of Applied ArtLeonardo da Vinci Bridge – a Piece of Applied Art



Even though it was never built, the con-cept of the bridge in it self is fascinating. The bridge span would have exceeded anything which had been built up to then. In order to comprehend the magnitude of the project one must consider that at that time, the largest stone bridge span was 37.5 metres, and even at the end of the stone bridge era, at the beginning of the 20th century, the largest span was only 90 metres – Friedensbrücke (1905), Plauen, Germany. Today the Wuchao River Bridge (1990) in Hunan Province of China, with a span of 120 metres, has the longest stone arch bridge span in the world.

Leonardo’s bridge is not only a vast structure, but a beautifully shaped struc-ture as well – and the shape serves a purpose. The basic load carrying system consists of three arches; one vertical arch carrying the vertical loads and two inclined arches – one at each side. The vertical arch, with its height to span ratio of about 1:6, seems to follow the thrust line. However, the required width of the bridge way would have given a very slen-der bridge with regard to lateral loading. In order to achieve lateral stability, Leon-ardo provided the bridge with the inclined arches, giving the bridge its characteristic appearance.

The artist’s interpretation

The timber bridge at Ås in Norway should not be regarded as a large-scale model of

to the apex. At the abutments there are fixed ends provided by bonded-in steel rods. The centre arch is made up of four segments, the other two of tree segments, which are rigidly connected by slotted-in steel plates and dowels. The arches re-present a great example of the possibilities in shaping glulam timber. The complex surface of the arches was specified by the co-ordinates of a 150x1150 mm surface mesh, and from these co-ordinates, the wood was shaped by a computer aided grinding machine.

The bridge deck is supported by the main arch in the middle, following the convex shape of the arches. At both sides, the deck has a sag as indicated by Leon-ardo’s sketch and the necessary support is provided by slender steel pillars. The use of stress laminated glulam beams for the bridge deck makes it possible to follow the smooth lines of the concept. The beams are pre-curved and clamped together by pre-stressed, high strength steel bars forming a continuous ribbon like slab. The deck is provided with a water tight membrane and a wearing course.

The bridge is highly exposed to weath-ering as it is provided with very little pro-tection by structural means. Metal clad-ding, plastic coating, wooden panelling et cetera, were all turned down for aesthetic reasons, leaving chemical protection as the only option for obtaining a reasonable operating life. Among the chemical alter-natives, creosote was ruled out for optical reasons (too dark) and CCA-treatment was ruled out for environmental reasons, ending up with a number of environmen-tally friendly systems in order to compen-sate for less effect and lack of long term experience.The applied systems were:

1) each single lamella in the arches is pressure treated with Scanimp, which is a heavy metal free agent of class AB, i.e., not recommended for soil contact

2) the glued, grinded and finished arch elements are pressure treated with Ultrawood, which is a water based wax emulsion giving the member a water-repellent surface

3) In order to further prevent ingress of water, the finished structure was pro-vided with two coats of oil stain with some pigmentation. This treatment

Leonardo’s bridge concept, but as an interpretation expressed in wood. The artist Vebjørn Sand was fascinated by the renaissance and in particular by the boldness and beauty of Leonardo’s bridge concept. He studied it thoroughly and was the driving force to materialize the idea into a real timber bridge. In cooperation between the artist and the Public Roads Administration, the glulam manufacturer, the architects and the consulting engi-neer, the basic principles of the concept were translated into a beautifully shaped wooden model.

The shape of the footbridge follows loy-ally the course of the lines of Leonardo’s little sketch, but in a more pronounced way. The use of glued laminated timber requires a lighter and more minimalistic structure – in reality a new structure. Still the new and modern glulam timber struc-ture possesses all the main structural ele-ments of the old stone bridge; the bridge way, with its sag at both sides, vaults over the arches in an elegant way. The main thrust arch carries the vertical loading and the inclined arches provide lateral stabil-ity – just like the stone bridge concept of Leonardo.

The timber bridge

The static system of the bridge consists of three non-hinged glulam timber arches with a rounded, triangular cross section decreasing in size from the abutments


has to be repeated with an interval of a few years.

4) In order to provide the areas of the glulam timber arches, which are particularly exposed to moisture, with additional protection, boron bars were inserted into pre-drilled holes near the abutments. These bars will be inactive as long as the timber stays dry, but with ingress of moisture, the boron will gradually be dissolved and locally prevent rot. The boron bars have to be regularly inspected and replaced if necessary.

The Norwegian design rules for bridges require a design service life of 100 years for all bridges – including timber bridges. With the above treatment, this require-ment cannot be fulfilled. The service life was estimated to about 40 years without any reconstruction works. An exception from the design rules was given on this point on artistic and aesthetic grounds.After two years of exposure, the structure still looks well. However, the massive cross-section of the arches and the change in temperature and moisture has caused some cracking. The cracking is still not alarming, but in the long term fissures on the upper surface, collecting water and allowing it to penetrate into the cross section will cause decay. Filling the fis-sures has been considered, but has been rejected. Usually a new fissure opens up in the interface between the filling material and the wood, and thus makes the situation even worse. However, the cracking is monitored and if the situation becomes worse, measures such as clad-ding, has to be taken.

Conclusion

Apart from durability concerns, one may conclude that the Leonardo da Vinci Bridge was a successful project. The bridge has attracted considerable attention and many positive comments. It is neither an engineer’s bridge nor the most efficient way of bridging a highway, but it serves its function, provides the road-users with a beautiful sight, the municipality with a sculpture and pedestrians and bikers pass-ing over the bridge with an experience. Last, but not least, the unusual and beauti-fully shaped bridge may lead to increased public interest for bridges in general.

Facts about the Leonardo da Vinci BridgeBridge site: Crossing E18 at Nygårdskrysset in Ås municipality near Oslo, NorwayType of Bridge: FootbridgeStructural system: One vertical and two tilted arches with fixed ends at the abutments and inter-connected at the apexTotal length: 109.2 mMain span: 40.0 mVertical clearance above road: 5.70 mClearance between handrails: 2.80 mYear of construction: 2001Material quantities: 90 m3 of glulam timber (Gl 36c), whereof about half the amount in the centre arch after having ground off about 40 m3. 120 m3 glulam timber in the stress laminated bridge deckCosts: Totally about NOK 12 millions, whereof the glulam timber amounted to NOK 4.1 millionsOwner: Norwegian Public Roads Administration, Eastern RegionDesign group: Vebjørn Sand (idea and artist), Reinertsen Engineering ANS (consulting engi-neers), Selberg Arkitektkontor AS (architects), Moelven Limtre AS and Norwegian Public Roads Administration, Directorate of Public Roads (advisors) and Norwegian Public Roads Administra-tion, Akershus (project management)Contractors: Norwegian Public Roads Administration, Akershus with Moelven Limtre AS as sub-contractor for production and erection of the timber structure.



Annotated reports from the Institute of Transport Economics (TØI)

Research has demonstrated impaired driving performance with increasing driving time. As many as about one-half of truck-drivers may have fallen asleep at the wheel at least once in their career as a driver. The crash risk tends to increase with driving time, especially after 9–11 hours. The amount and quality of sleep before driving seems to have a stronger effect than driving time on perform-ance and risk. There is a clear scientific

rationale for regulating resting and driv-ing periods. Violations of hours of service regulations are frequent, too short rest periods between working periods being an especially common violation. Low compliance seems to be partly due to complex regulations. Harmonization across countries concerning interpretation of the regulations, tolerance levels, and sanctions, as well as increased level of surveillance is likely to result in increased

compliance and safety. The role of trans-port companies in promoting safe driving should also be focused.

Fatigue- and Sleep-Related Road Accidents

Title: IBIS Logitrans. Users’ evaluations of real-time route information in TrondheimAuthors: Katrine Næss Kjørstad, Unni B. LoddenSeries: TØI report 638/2003.Language: Norwegian with English summary.

Users’ Evaluations of Real-Time Route Information

On route 4 in Trondheim city there are introduced real-time route information through screens on 5 bus stops, through SMS warning service and on the Internet. This report gives results from the evalua-tion of the public transport users response to these measures. Real-time route infor-mation on bus stops are percieved as useful. The waiting time is experienced as shorter when receiving real-time information. Real-time route informa-tion through SMS or on the Internet are not as useful measures. Those who travel frequently and regularly will benefit from the SMS service, but it is percieved some-what cumbersome to use. Young public

transport users are more likely to use the newest sources of information, while at the same time they use timetables to a

The waiting time is experienced as shorter when receiving real-time information.

Title: Hours of service regulations and the risk of fatigue- and sleep-related road accidents. A literature review.Authors: Astrid H. Amundsen and Fridulv SagbergSeries: TØI rapport 659/2003Language: EnglishSummary: http://www.toi.no/program/program.asp?id=213817

Elderly Drivers and Traffic Safety

The study examines whether the use of various tests of vision and cognitive functioning can identify elderly drivers with reduced ability to drive safely in traffic. The driving skills of 88 elderly drivers were evaluated, and the drivers also completed various tests of vision and cognitive functioning. A combina-tion of four simple tests predicted 78 per

cent of the drivers who were regarded to represent a danger to either themself or to others in traffic. These included: reduced acuity under glare conditions, defects in the central field of vision, cognitive impairments/dementia, and impaired attention. None of these tests are included in the medical examination elderly drivers have to complete today.

Title: Vision and cognitive functionig among drivers aged 70 years and older. Importance for driving perform-ance.Authors: Forfattere: Pål Ulleberg and Fridulv SagbergSeries: TØI rapport 668/2003Language: Norwegian with English summarySummary: http://www.toi.no/program/program.asp?id=259577

Title: Influencing driver behaviour and safety by road system improvementsAuthor: Fridulv SagbergSeries: TØI report 648/2003.Language: Norwegian with English summary.

Influencing Driver Behaviour and Safety by Road System ImprovementsOn the basis of a literature survey, the issue of influencing driver behaviour by a user-based approach to road design and driver information is discussed. The importance of considering driver infor-mation needs and cognitive capacities and limitations is focussed. Road layout, signs and markings should be in accord-ance with driver expectations, to avoid

errors and increased crash risk. Special topics that are discussed include effects of road design on speed, the risk of wrong-way driving (especially on motorways), criteria for optimal direction signing, and how the road system should better accom-modate the information needs of elderly drivers.

greater extent than older people. The new information sources will not be able to replace the traditional ones, but they can function as a supplement.


Annotated reports from the Institute of Transport Economics (TØI)

New Traffic - New Neighbours?

The report shows that traffic changes may trigger relocation processes, and that such processes may be self-reinforcing. This is in accordance with Thoma Schelling’s “tipping point” model. Data from five areas in inner Oslo east, with road traffic developments during the 1990s, show that Norwegians with children moved out of, and foreigners with children moved into areas that experienced traffic increases.

Title: New traffic - new neighbours? Traffic and segregation in Oslo inner eastAuthor: Torkel BjørnskauSeries: TØI report 652/2003.Language: Norwegian with English summary.

Traffic changes may trigger a process towards segregation.

Speed, Feelings and Risk

The present report discusses inner mecha-nisms involved in the appraisal of risk, information processing, and the drivers choice of cruising speed. A crucial issue is how risk is appraised and how processes linked to risk appraisal and speed choice should be modelled. Appraisals of risk are modelled from an alternative perspective that emphasizes emotions and feelings and is based on neurological research. This approach offers an alternative to “rational “ decicison-making, and we

have named it Damasio’s model. While emotions are defined as unconscious bodily responses, feelings are defined as ‘feeling an emotion’, i.e. making the reac-tions and changes of the body conscious. Damasio’s distinction between primary emotions, secondary emotions and feel-ings, and the ability to monitor the organ-ism unconsciously as well as consciously, are the main elements in what we choose to call the risk monitor. A model of the risk monitor is proposed.

Title: Speed, feelings and risk: A discussion of inner mechanisms involved in drivers’ speed choice. SIP Driver behaviour models: Report 3Authors: Truls Vaa, Torkel BjørnskauSeries: TØI report 607/2002.Language: Norwegian with English summary.

There was an opposite tendency in one of two areas with traffic decrease. In addi-tion, areas with traffic increase, exhibited a poorer development in living condi-tions than areas with traffic decrease. The results show that traffic changes may trigger a process towards segregation, and that it can take place on low geographical levels.


Annotated reports from VTT, Building and Transport

How Does Construction Work Cater to the Needs of Public Transport?

Construction work on the Kamppi Centre, in place of the Helsinki main bus terminal, started in the summer of 2002 and caused a radical change in the arrangements of public transport in the City Centre. VTT studied the effects of traffic arrangements, including the giving of information and guidance, especially on passenger satis-faction. The survey was mainly carried out by person interviews directed at pas-sengers, taxi drivers, nearby businesses and persons participating in the planning and implementation processes for public transport arrangements under these unu-sual conditions.

According to the study, the traffic arrangements and passenger information at Kamppi construction site were quite successful. However, passengers felt that their journey times have become longer, and that punctuality and drivers’ knowl-edge about the public transport system has got worse. On transfer trips in the City of Helsinki, use of the Metro and buses has increased, whereas walking and the use of trams have decreased. Travel times on several routes have grown and operat-

ing costs have increased noticeably.The study showed that problems caused

by construction sites can be reduced by providing concise information in a clear form and by such means that are avail-able to everyone in the area. Guidance on transport and pedestrian routes in areas surrounding the construction site is very important as well.

Title: The organisation of public transport and provision of passenger information at Kamppi construction siteAuthors: Heidi Sandberg and Marja RosenbergSeries: Ministry of Transport and Communications, FITS publications 26 /2003The Finnish report can be downloaded from:http://www.vtt.fi/rte/projects/fits/julkaisut/hanke1/fits26_2003.pdfLanguage: Finnish with English abstract

Effects of Variable Speed Limits on Injury Accidents in FinlandIn Finland several road sections have been fitted with variable speed limits (totalling 250 km). A study was conducted on the impacts of the variable speed limits on injury accidents.

The evaluation study included eight two-lane road sections. The control sys-tems were based on road and weather con-dition data. The same types of roads with fixed speed limits were used to control the general trend in the injury accident risk. The length of the follow up periods was up to 12 years.

Preliminary results showed that speed limit systems which use fibre optic or LED signs, which base the control on automatic classification of road condition situations, and which include variable slippery warn-ing signs, seemed to decrease the injury risk. The effect was -13 per cent in winter and -2 per cent in summer. For the other group of systems the safety was reduced, the effect on injury risk being +8 per cent

in winter and +21 per cent in summer. These systems used electromechanical signs, they had no automatic classification system for the control of speed limits, and no variable warning signs were included. However, the results were not statistically significant.

The preliminary results highlight the importance of a high quality of variable speed limit systems. Previous research has shown that the lowest speed limits in VMS are used very seldom. Conse-quently, it is critical to automatically monitor and efficiently recognise hazard-ous conditions and provide the informa-tion to road users. In addition, the choice of sign technology may be important in addition to dynamic variable warnings. In Finland, speed limits are lowered during wintertime on most two-lane roads. Vari-able speed limits make it possible to show higher speed limits under good condi-tions. With high quality systems the aim

Title: Safety effects of variable speed limit systemsAuthors: Pirkko Rämä, Anna Schirokoff and Riikka RajamäkiSeries: Finnra reports 54/2003Language: Finnish with English abstract

Construction work on the Kamppi Centre, June 2003.

to improve fluency of traffic flow seems possibly to parallel an improvement in traffic safety.


Annotated reports from the Danish Road Directorate (DRD)

This report describes the calculation of road surface friction based on texture values. The friction is measured with a ROAR device and stored every 5 m. The texture is measured with a laser and stored every 0.5 mm. Both types of devices are mounted on the same equipment having a laser and a ROAR positioned in the outer and inner wheel path. This makes it possi-ble to measure friction and texture values in the same run in both wheel paths.

Wavelet transformation of the texture profile has been used as an index to be correlated with the measured friction. Calculated MPD (Mean Profile Depth) values in accordance with the ISO stand-ard 13473-2 have also been analysed. In Denmark, road pavements with a friction value below 0.40 measured by the ROAR, are regarded as slippery roads and hence the analysis has mainly dealt with data

obtained on pavements with friction below 0.40.

The analysis showed that the calibration of the distance measuring devices for the texture and the friction plays an impor-tant role for obtaining a good correlation between the friction and texture measure-ments. It was discovered that differences up to ± 5 m between the different distance measures could occur on a 3 km road sec-tion. The report shows some mathemati-cal methods, which can compensate for the differences in the distance measure-ments and hence positions the measured data equally.

The models described in the report, which calculate road surface friction based on texture data, gives a good cor-relation between the two data for sections having low friction levels, although the difference in the distance measures com-

Road Surface Friction Based on Texture Values

Title:Road surface friction based on texture valuesAuthors: Henrik Aalborg Nielsen og Henrik MadsenSeries: Report 124Available on: http://www.vd.dk/pdf/virap124-1.pdf and http://www.vd.dk/pdf/virap124-2.pdf in Danish

Title: Asphaltic Plug JointsAuthors: Vibeke WeganSeries: External Notes 17External Note 17 is written in Danish and can be found on the internet at the following address: http://www.vd.dk/pdf/eksnot17.pdf

When inspecting asphaltic plug joints, various deterioration mechanisms can be seen. The aggregate loosens from the surface of the joint, the aggregate can be found loose inside the joint, the joint seal-ant cracks if it becomes too hard or it is spread over the adjacent asphalt pavement if it becomes too soft. The joint can also become rutted or adhesion failure can be seen between the joint and the adjacent asphalt pavement.

When inspecting existing joints in 1998, the main defect with asphaltic plug joints was that the aggregate in the joint had loosened from the joint sealant which resulted in a leaky joint. The phenomenon was seen mainly in the driving tracks, which points to the fact that the repeated

passages of traffic over the joint cause poor adhesion between the joint sealant and the aggregate.

In order to minimise the risk of making asphaltic plug joints where the adhesion between the joint sealant and the aggre-gate is decreased due to the repeated passages of traffic, various test methods have been examined in the laboratory which can simulate this mechanism. By comparing practical experiences of dif-ferent contractors with experiences from full-scale testing, where seven different asphaltic plug joints were laid, a test method has been developed. The test method is expected to be able to predict whether the adhesion between the joint sealant and the aggregate is satisfactory

or whether it must be expected that it will decrease in time.

Experiences of the full scale test where the material have been characterised and the conditions during laying have been registered together with results of laboratory testing are expected to give a good basis for the coming revision of the Danish Road Standards for asphaltic plug joints.

Asphaltic Plug Joints

plicates a qualitative comparison between the calculated and the measured friction values. For road sections with a high fric-tion level, the calculated friction values are higher than the measured friction values. This is however considered not being critical, as the target is to pinpoint the road sections with low friction.

As a by-product of the data analysis it turned out that road surface friction values are mainly related to the wavelet coefficients associated to the wavelength length between 7 and 8 mm.

One of the four seminars at the 75th jubilee of the Danish Road Institute addresses the work of the Institute within the field of “Knowledge on local roads”.

The Danish Road Institute has for many years worked with local roads and was among the first in Denmark to introduce management systems for municipalities.

Today the use of management systems

and systematic road maintenance has advanced further by introducing new alternative forms of contracts such as per-formance contracts and road partnering.

Irrespective of the type of contract, it is still necessary to have knowledge of road networks condition and changes in the contract period.

The articles in the report describe the

Knowledge on Local Roads

Title: Knowledge on local roadsSeries: Report 125Available on: http://www.vd.dk/pdf/125vi.pdf

use of alternative contract forms and the collection and use of condition data on local roads.


Annotated reports from the Danish Road Directorate (DRD)

One of the four seminars at the 75th jubilee of the Danish Road Institute addresses the work of the Institute within the field of “Knowledge on big roads”.

What knowledge on big roads will be necessary in some years? It is now that ongoing research and development should create the base for knowledge about the design, construction and maintenance of bigger road constructions.

Report 126: “Knowledge on big roads” contains – apart from the presentations made at the seminar “Knowledge on big roads” - an additional paper on the sub-ject. The report does not cover the entire

knowledge in this big field. However, it does reflect important elements of the future work of the Danish Road Institute.

The report 126 contains the following papers:

- Upgrading of the road network – the traffic is growing: how should we upgrade the roads, so that they have a longer life-time?

- Designing of pavements: The Danish Road Standards and the American AASHTO 2002 Design Guide

- Maintenance of structures – bridges are the main cross points of roads and this requires special maintenance

Knowledge on Big Roads

Title: Knowledge on big roadsSeries: Report 126Available on: http://www.vd.dk/pdf/126vi.pdf

- Long-life pavements – what have we learnt from the past and how should we construct roads in the future

- Flexible stone mastic joints – how good is their lifetime?

One of the four seminars at the 75th jubi-lee of the Danish Road Institute addresses the work of the Institute within the field of “Knowledge about the construction of roads”.

Several contributions describe that there are soon to come changes. As an example, the Danish Road Standards must be adjusted as a result of European direc-tives, road materials must be CE-marked and test methods for road materials must be changed. As a result of new technol-

ogy, there will undoubtedly be changes in the field of quality control of road materi-als in situ.

There is increased focus on other types of road pavements than the traditional, including long-life cement stabilised pavements. An important aim is to reduce the inconvenience for the users, since long-life pavements do not require main-tenance so frequently. The co-operation between the Danish Road Institute and other institutions in Europe is described.

Knowledge about the Construction of Roads

Title: Knowledge about the construction of roadsSeries: Report 127Available on: http://www.vd.dk/pdf/127vi.pdf

Geotechnical investigations are of great importance for the optimisation of major road constructions. Reuse of road materi-als and recycling of non-road by-products in the road sector have reached a high level, which will be maintained.

One of the four seminars at the 75th jubi-lee of the Danish Road Institute addresses the work of the Institute within the field of operation of roads, which primarily covers pavement condition measurements and modelling of pavement deterioration.

The primary goal is to give the road user a safe and comfortable trip with good passability. These measures must be reached within the framework of various legal requirements, economic and techni-cal possibilities as well as wishes from politicians, the road users and the roads’ neighbours. As can be seen there are many (often diverging) interests in the operation of roads and this will be increased in the coming years. With increased traffic on the roads there will be an increasing requirement and wish for more focus on

maintenance of road pavements and at the same time, it will become more difficult to work on the road.

The Danish Road Institute contributes to the knowledge on the operation of roads through own work, co-operation with the Danish road sector and partici-pation in international research projects. Distribution of knowledge has high priority, which means that the Institute’s employees continuously try to pass on knowledge to others and at the same time are aware of the latest knowledge which could be used in the Danish road sector. The efforts of the Danish Road Institute regarding the running of roads is aimed primarily at pavements where we develop tools and methods which can make the work in Danish road administrations

Knowledge on Operation of Roads

Title: Knowledge on the operation of roadsSeries: Report 128Available on: http://www.vd.dk/pdf/128vi.pdf

more effective and where we also act as the most important supplier of pavement measurements and condition surveys in Denmark.The reports contains five contributions which deal with optimisation of pave-ment maintenance, pavement condition measurements in Denmark, European harmonisation of friction measurements, a new point of view on the evenness of roads and finally road noise.


Exhaust Emission Variations for Short Engine Stops and Driving Times for Petrol Cars with and without Catalyst Extra exhaust emissions after short, 10 to 60 minutes, engine stops appear not to approach zero linearly as the stop time goes to zero. Particularly large devia-tions are those of nitrogen oxides and particulates for cars without as well as with catalyst. Extra emissions of nitrogen oxides for catalyst cars are higher for 1 h stop time than for both shorter and longer stop times.

Large systematic variations in emis-sion levels were confirmed for extended driving distances during dynamometer runs also after a 23 km warm-up. From this follows that the reduction in nitrogen oxides with time estimated in national inventories, if these circumstances are considered, can be expected to decrease.

Road traffic exhaust emissions calcu-lated from models are frequently split into hot engine emissions, cold start emissions and evaporative emissions. The extra emissions at start are expressed as the difference between emissions over a particular driving cycle when the vehi-cle is run with a cold started and with a warm engine. Engine stop times, as well as meteorological conditions, have strong influence on start emissions at various engine temperatures. Available experi-mental data, suitable for assessment of start emissions, usually reflect a situation

where the engine and ambient tempera-tures are the same. Most frequently the temperature is 20ºC or below, and the engine stop time is at least 12 h.

The present study focuses on the influ-ence of short engine stops – 10, 20, 30, 60 minutes – on exhaust emissions, by repeating the same driving cycle 28 times during one day.

The relationships of extra start emis-sions observed between a cooling water temperature of 20ºC and the maxi-mum temperature indicate that a linear approach to zero when the temperature goes up in most cases results in consider-able relative over- or underestimations, the former particularly for particles and the latter frequently in the case of nitro-gen oxides.

This could be expected to decrease the reduction in nitrogen oxides from the middle of the 1980s until year 2000 which has been deduced so far.

The results also indicate a higher pro-portion of cold start emissions for most substances.

The results obtained must be regarded as unexpected and might have consider-able consequences for both emission models and emission factors.

Title: Exhaust emission variations for short engine stops and driving time for petrol cars with and without catalystAuthor: Ulf Hammarström Series: VTI meddelande 931Language: Swedish with English summaryThe report is also available in Swedish as a pdf file on www.vti.se under Reports.

Number of Road Accidents before and after ResurfacingThis is the third study of the effects of resurfacing measures on the number of road traffic accidents that Region West of the Swedish National Road Administra-tion has commissioned.

When the two resurfacing years are examined individually, an accident increase is found for all police-reported accidents after resurfacing. If personal injury accidents are analysed separately, accident decreases are found for both resurfacing years: the number of accidents decreases also when only accidents with seriously injured and killed are analysed.

When the two years are examined together, an increase of 3 per cent is found for all police-reported accidents, a decrease of 7 per cent for personal injury accidents

tinguished. There is a certain tendency for the number of accidents to increase after resurfacing on roads with high IRI values and a decrease on roads with an IRI value of 1.2–1.8 mm/m.

and a decrease of 13 per cent for accidents with seriously injured and/or killed. The decrease in personal injury accidents and accidents with seriously injured and/or killed is the becomes larger the greater the amount of precipitation that has fallen during the day (24 hours) when the acci-dent occurred. When weather information from the police/accident-report forms has been used, an approximately similar decrease in accidents is obtained for pre-cipitation and dry weather.

In this study the road network has been divided into a number of classes depend-ing on road surface standard before and after the measure, i.e. different IRI and rut depth classes. In the case of different rut depth classes no pattern could be dis-

Title: Analysis of traffic accidents before and after resurfacing measures.Resurfacing years 1997 and 1998 in Region West of the Swedish National Road AdministrationAuthors: Hans Velin and Gudrun Öberg Series: VTI meddelande 929Language: Swedish with English summaryThe report is also available in Swedish as a pdf file on www.vti.se under Reports.

Annotated reports from the Swedish National Road and Transport Research Institute, VTI

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Annotated reports from the Swedish National Road and Transport Research Institute, VTI

Emission of Wear and Resuspension Particles in the Road EnvironmentParticles from wear and resuspension in the road environment are difficult to handle in emission modelling for many reasons. Primary wear emissions due to that the emissions are affected by a large number of factors related to material properties, traffic characteristics and temporal and spatial variations in composition of vehicle fleet. Estimations made from measurements in ambient air needs source apportionment studies meanwhile laboratory tests result in pinpoint samples conducted during non-

particles as well as an overview of relevant emission factors.

realistic circumstances.Resuspension depends, except from

the addition of primary wear partcles, also on addition from particles from exhaust and the environment. Road surface characteristics and meteorology are important factors affecting the resuspension process.

This report summarises how some different models (e.g. AP-42, Vluft, Dispersion) handle wear and resuspension particles and provides an overview of factors affecting the emission of these

Title. Emission of wear and resuspension particles in the road environment. A literature reviewAuthor: Mats GustafssonSeries: VTI meddelande 944Language: Swedish with English summaryThe report is also available in Swedish as a pdf file on www.vti.se under Reports.

Calculation Model for Encroachment Costs of Infrastructure InvestmentsIn the cost-benefit analyses applied by the Swedish National Road Administration and Swedish National Rail Administra-tion no monetary values are included for the environmental harm caused by a new piece of transport infrastructure other than noise and air pollution emissions from the traffic. These effects may for example consist of the physical encroachment by a road or a railway on an area of recrea-tional, natural and/or cultural value.

This report outlines a method of cal-culating “encroachments costs”. First a limited number of typical cases are defined, which can be described using a few continuous variables together with class variables.

A typical case considered in this project is when a road or a railway constitutes a barrier between a river, a lake, or a bay, and a built-up area. Four existing cases have been studied where earlier encroach-ments have been made in order for the respondents to be able to fully understand the scenario in the questionnaire, and answer the questions in a proper manner. In all cases CVM (Contingent Valuation Method) with binary choice has been used to find the willingness to pay (WTP) for replacing the existing road (and railway in one of the cases) with a tunnel.

A mean value of the WTP for the hypo-thetical tunnel in each case study can be calculated on the basis of the ‘yes’ or ‘no’ response to the CV question by construct-ing a cumulative frequency curve. First, a non-parametric estimation is made without an explanatory purpose. These

(2b) WTP = α2 + γ2X2 for those living in the rest of the town

where X1 is a distance variable and X2 is a variable for the frequency of visiting the area next to the barrier. The values of α1, α2, γ1and γ2 depend on Z, i.e. the charac-teristics of the road or railway constitut-ing the barrier such as traffic volumes and road or rail track width. Y-variables for socio-economic variables are not needed in the calculation model.

values can serve as a benchmark for the performance of the calculation model aimed at. The main idea behind the cal-culation model is to eliminate the need for a new ex ante study for every project, which would otherwise entail the risk of strategic bias. For this purpose, however, we must establish which variables deter-mine the WTP:

WTP = f(X, Y, Z)

where WTP is the willingness to pay to avoid the encroachment, X is a vector of variables that describe the exposure (for example the distance between the residence and the road or railway), Y is a vector of socio-economic variables (age, sex, income etc) and Z are variables that describe the characteristics of the barrier, i.e. the piece of infrastructure (type of road, traffic volumes etc).

In the three case studies where a road forms a barrier to a lake/sea the inhabit-ants are divided into two groups: (1) those who live so close to the barrier that they can see or hear the traffic and (2) the rest of the town. We have found that people living near the barrier are disturbed in proportion to the distance between the residence and the barrier. For the rest of the town’s inhabitants the location of their home has little importance. Their valua-tion of getting rid of the barrier depends on how often they visit the area next to the barrier.

(2a) WTP = α1 – γ1X1for those living close to the barrier

Title: Calculation model for encroach-ment costs of infrastructure investmentsAuthors: Stefan Grudemo, Pernilla Ivehammar and Jessica Sandström Series: VTI meddelande 939Language: Swedish with English summaryThe report is also available in Swedish as a pdf file on www.vti.se under Reports.

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Nordic Road and Transport Research 3-2003