Transportation Research Part A 40 (2006) 792–799

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Short Communication

Sampling mobility index: Case study in Assis—Brazil

Fernando Frei *

Faculdade de Ciencias e Letras de Assis, UNESP, Av. Dom Antonio, 2100, Cep 19800906—Assis, SP, Brazil

Received 25 July 2005; accepted 16 December 2005

Abstract

The objective of this work is to present an index which may synthesize a set of indicators of mobility for medium sizecities urban centers. Three great areas were selected to compose the mobility index: pedestrians, motor vehicles and cycling.The Sampling Mobility Index is given by the sum of the punctuation the indicators selected and can to result in 700 points,the best result to mobility, and 0 points, the worse to mobility. The result obtained is given by the Sampling Mobility Indexequal to 390. This result indicates a critical situation in Assis, as far as mobility is concerned.� 2005 Elsevier Ltd. All rights reserved.

Keywords: Mobility; Index; Indicators; Urban centers

1. Introduction

The use of private motor cars and their deleterious effects in the cities and urban areas have been the subjectof several studies. Researchers recognize that private motor cars are one of the main causes for the decline inthe quality of living in the cities (Reutter and Reutter, 1996; Mackett et al., 2003).

The number of private motor cars has been steadily increasing in the last decades. According to Bonsall(2000) quoted by Stopher (2004), in the United Kingdom the rate of vehicles per residence rose from 30%,in 1960, to 70%, in 1995. In several regions of the United States of America, in the year 2000, the ownershiprate was over one vehicle per owner. Similar date were found in other countries, too. In addition to these facts,the amount of trips by private motor cars, buses, trains and airplanes has also dramatically increased duringthese last decades (Schafer, 1998).

The increase in the number of private motor cars and in the amount of trips bring as by products anincrease in air and sound pollution, excessive consumption of natural resources, time spent in traffic jams,increase in the consumption of non-renewable energy, accidents, etc. According to Pires et al. (1997), quotedby Marin and Queiroz (2000), in Brazil, about two third of the hospital beds in the orthopedics and trauma-tology sectors are occupied by victims of traffic accidents, with an average cost of 20,000 dollars for the seri-ously injured victims.

0965-8564/$ - see front matter � 2005 Elsevier Ltd. All rights reserved.

doi:10.1016/j.tra.2005.12.004

* Tel.: +55 18 33025896; fax: +55 18 33243749.E-mail address: ffrei@assis.unesp.br

F. Frei / Transportation Research Part A 40 (2006) 792–799 793

On the other hand, urban areas constitute regions with specific and complex needs concerning the transpor-tation of people, food and other products and that demands careful planning and sustainable developing pol-icies (Akinbami and Faradeb, 1997). Having that in mind, special attention should be given to the relationsbetween the use of private motor cars, pedestrians and cyclists. The mobility of people in urban areas demandsa broad perspective which should take into account sustainable contexts.

Indicators and indexes have been used as important instruments in the orientation of suitable policies forthe transport sector. For this reason, statistical systems in developing countries should have as their aim tobroaden their scope and to assure the reliability of the data collected, in order to offer effective help for theimprovement of the standard of living in the cities. For this same reason, local authorities should guaranteerapidity and regularity in data collecting as well as the dissemination of information to the public (Lake,1996).

Indicators are easy to define and to quantify, allowing reliable results; they are considered technicallyappropriate for geographical as well as temporal comparisons. For instance, in the study of traffic jams,Levine and Wachs (1998) used as indicators the measure of occupation by vehicles. The quality of the servicesprovided by companies in the transportation of passenger (Hensher et al., 2003), the behavior of drivers(Parker et al., 1995; West et al., 1993; Marın-Leon and Vizzotto, 2003), the use of bicycles (Krizek andRoland, 2005; Bergstrom and Magnusson, 2003; Ortuzar et al., 2000), and researches with pedestrians (Liet al., 2005; Keegan and Mahony, 2003) are some of the themes which are generating indicators for the assess-ment of factors which affect transport and mobility.

The objective of this work is to present an index which may synthesize a set of indicators of mobility formedium size cities urban centers with a population between 100 thousands and 500 thousands inhabitants,approximately.

2. Characteristics of Assis city

Assis is located in the western region Sao Paulo State, Brazil. With an estimated population of 91,766inhabitants (SEADE, 2004) it has 38,183 vehicles, comprising 21,732 private motor cars, 9803 motorcyclesand similar vehicles, 244 buses for urban transport and 6381 trucks and similar vehicles (SEADE, 2002).

Compared with the other 644 cities in Sao Paulo State, Assis may be considered as having a very high num-ber of motor car vehicles (1 per each 2.4 inhabitants), and could be placed among 35 other cities with a highproportion of vehicles. The number of motorcycles and similar vehicles has increased significantly during thelast years, both due to the low cost of this type of vehicle and to the lack of employment opportunities, as themotorcycles have been used as a new kind of hired transport, known as ‘‘motorcycle taxi’’ (mototaxi). Morethan 25% of the total number of vehicles in the city consist of motorcycles, one of the highest percentage com-pared with other cities in Sao Paulo State.

The number of bicycles is also high as the topography of the city favors this means of transportation.

3. Selected indicators and assessed measures

Three great areas were selected to compose the mobility index: pedestrians, motor vehicles and cycling.

3.1. Sidewalk width and free walking pass

There is no standard measure for the sidewalk width in Brazil. At present, some municipalities have pre-sented legislation to set appropriate standards. According to researches on the legislation of different munic-ipalities, the sidewalk width varies from 2 to 4 m (Prefeitura Municipal de Londrina—PR, 2005; PrefeituraMunicipal de Porto, 2005; Prefeitura Municipal de Vitoria—ES, 2005; Prefeitura Municipal Cascavel—PR,2005 and Prefeitura Municipal de Camboriu—SC, 2005).

Selected Indicator:

(a) Sidewalk width: measured in meters.(b) Free walking pass: measured in meters.

794 F. Frei / Transportation Research Part A 40 (2006) 792–799

3.2. Pedestrian traffic lights and cycling lanes

Indicator which shows how much the public administration and the society consider pedestrians andcyclists in comparison to motor vehicles.

Selected indicator:

(a) Number of traffic lights for pedestrians.(b) Cycling lanes measured in meters.

3.3. More than one person per vehicle

Indicator which measures the use of the motor cars in terms of the number of people transported in privatevehicles. A relevant indicator for medium sized and big cities, considering problems such as traffic jams andecological awareness.

Selected indicator:

(a) Number of private motor vehicles carrying more than one person.

3.4. Use of safety belts and respect for red and yellow traffic lights

This indicator represents the driver’s behavior in relation to his/her concern with the current trafficlegislation.

Selected indicator:

(a) Number of vehicles in which driver and passenger are with safety belts.(b) Numbers of vehicles whose drivers obey the traffic lights (i.e. have not broken the law).

3.5. Vertical and horizontal signaling

This indicator represents the municipal traffic authority concern in carrying out periodic maintenance andupdating of traffic signals for pedestrians, cyclists and motor car drivers.

Selected indicator:

(a) Number of vertical and horizontal signaling.

4. Methodology

4.1. Samples

In developing countries such as Brazil, the systematic production of indicators has been steadily increasingin recent years. In spite of that, medium sized cities and towns make little use of indicators as guiding supportfor public policies. Due to the insufficiency of indicators the use of survey research is one of the alternatives toprovide the necessary data. This way, for each selected indicator survey researches were carried out in differenthomogeneous zones in the city. These homogeneous zones were obtained through cluster analysis by means of10 socioeconomic indicators from the last national census (IBGE, 2000). Each zone represents socioeconomicstrata in such way that every area of the city was looked at.

In order to obtain the sidewalk width indicator, the free walking pass indicator, and the vertical and hor-izontal signaling indicator, 10 blocks in each homogeneous zones were chosen at random, amounting to 70blocks. For each block, one side of the sidewalk was chosen and its width was measured on a central point

Fig. 1. Sidewalk measurement.

Fig. 2. Free walking pass measurement.

F. Frei / Transportation Research Part A 40 (2006) 792–799 795

(from A to B as shown in Fig. 1). The free walking pass was measured on this same side, on every 15 m orwhere any kind of obstacle was found, except trees (see Fig. 2). The number of horizontal and vertical trafficsignaling were obtained on the crossroads within the chosen blocks.

Those indicators which refer to the vehicles themselves (more than one person pre vehicle, use of safetybelts and respect for traffic lights) were obtained on 10 of the busiest crossroads with traffic light, on differentdays and in different hours of the day (1884 private vehicles for safety belt use indicator, 3130 private vehiclesfor respect for traffic lights indicator and 2255 private vehicles for more than one person per vehicle indicator).

4.2. Constructing the sampling mobility index—SMI

An index is the numeric sum up of several indicators; sometimes just one indicator may be considered as anindex. However as our objective is to synthesize the mobility conditions in the city of Assis, the mobility indexis obtained by using the averages of the selected indicators. This procedure is adopted as it facilitates all thecalculations, and also facilitates its dissemination.

(a) Sidewalk width indicator—SWI

SWI ¼ 2:5�Xn

i¼1

SWIi

,n

!" #� 100 ð1Þ

where SWIi is the ith sidewalk width; 2.5 m is the desirable standard measure; n is the number ofsidewalk.

796 F. Frei / Transportation Research Part A 40 (2006) 792–799

(b) Free walking pass indicator—FWPI

FWPI ¼ 2; 0�Xn

i¼1

FWPIi

,n

!" #� 100 ð2Þ

where

FWPIi is the ith measure of the free walking pass,2.0 m is the desirable measure,any value FWPIi > 2,0) FWPIi = 2.0.

(c) Vertical and horizontal signaling indicator—VHSI

VHSI ¼X

SVH=n� �h i

� 100 ð3Þ

where

VHSI is the number of streets with suitable vertical and horizontal signaling, visible by drivers andpedestrians,n is the total number of streets r which were observed.

(d) Safety belt use indicator—SBUI

SBUI ¼X

SBU=N� �h i

� 100 ð4Þ

where

SBU is the number of people (observe in each vehicle) wearing safety belts,n is the total number of people which were observed.

(e) Respect for traffic lights indicator—RTLI

RTLI ¼X

RTL=n� �h i

� 100 ð5Þ

where

RTL is the number of vehicles observed during a certain period of time which have respected trafficlights,n is the total number of vehicles observed during this time.

(f) Pedestrians traffic lights indicator—PTLI

PTLI ¼X

PTL=N� �h i

� 100 ð6Þ

where

PTL is the number of traffic lights for pedestrian,n is the total number of existing traffic lights.

(g) More than one person per vehicle indicator—MOPVI

MOVI ¼X

MOPV=n� �h i

� 100 ð7Þ

where

MOPV is the number of vehicles with more than one person,n is the total number of vehicles.

(h) Cycling—CI

The indicator for cycling is not assessed as the other indicators. However, for a city that builds andimproves cycling lanes, 25 points are added to the mobility index—MI as a bonus for that kind of action.

Other indicators may be added to the index, according to the context of the city. For example traffic jamindicator or lowered sidewalk curb indicators, the latter would show concern for the mobility of disablepeople.

Table 1Representation of sampling mobility index

Quintile Interval of points SMI Signaling

1� 0–140 Red darkness (RD)2� 140–280 Red clear (RC)3� 280–420 Yellow (Y)4� 420–560 Green clear (GC)5� 560–700 Green darkness (GD)

Fig. 3. Color signaling system.

F. Frei / Transportation Research Part A 40 (2006) 792–799 797

The sampling mobility index is given by the sum of the indicators selected

SMI ¼XðSWIþ FWPIþ VHSIþ SBUIþRTLIþ PTLIþMOPVIþ ICÞ ð8Þ

The index final result may reach as many as 700 points without the addition of the cycling indicator bonus.In order to facilitate the reading of the results, the index may be presented in quintile (Table 1). The use offigures which can be helpful in educational campaigns and also facilitate the presentation of the results tothe population is adopted here by the creation of a five color signaling system (Fig. 3), referring to each inter-val of the quintile.

According to Fig. 3, for each interval of points in the index, there is a corresponding color. The dark redcolor indicates that society and administrators should intervene immediately in order to reverse the situation.The results associated to the red color also indicate the necessity of interventions by society and administra-tors, although the situation is not on a critical level. The yellow color is characterized as an alert; which meansthat the mobility situation in the city is not good and that some targets should be established in order toincrease the points for the indicators with lower punctuation. The light green color indicates a good situation;the results should be monitored with the objective of keeping the indicators with higher punctuation andimproving the indicators with lower punctuation. At last, the dark green color indicates the desired situation;the existing indicators should be monitored and actions should be extended for others indicators in sectors notyet contemplated.

5. Results

The results of each indicator are shown to follow:

SWI ¼ ½2:5� ð1:96þ 1:85þ 1:97þ � � � þ 2:40=70Þ� � 10) SWI ¼ 78

FWPI ¼ ½2:0� ð1:30þ 1:21þ 1:31þ � � � þ 1:60=350Þ� � 100) FWPI ¼ 65

798 F. Frei / Transportation Research Part A 40 (2006) 792–799

VHSI ¼ ½ð20=28Þ� � 100) VHSI ¼ 71

SBUI ¼ ½ð919=1884Þ� � 100) SBUI ¼ 49

RTLI ¼ ½ð2789=3130Þ� � 100) RTLI ¼ 89

MOPVI ¼ ½ð860=2255Þ� � 100) PTLI ¼ 38

PTLI ¼ ½ð0=16Þ� � 100) PTLI ¼ 0

The cycling indicator was equal to zero

IMA ¼ 390

The result obtained is given by the Mobility Index Amostral equal to 390, which corresponds to a quali-tative result in the five color signaling system equal to the yellow light.

6. Discussion

The results presented by the indicators show a critical situation in Assis, as far as mobility is concerned.The pedestrian traffic light indicator—PTLI was equal to zero, showing a total lack of concern for pedes-

trians on the part of the authorities. The statistic data mentioned earlier, presents Assis, compared to othercities in Sao Paulo state as having a high number of motor vehicles in relation to is inhabitants. This situationassociated with the lack of appropriate actions on the part of the authorities and the citizens produces unequalresults when we compare the mobility indicators. Take, for instance, the more than one person per vehicleindicator—MOPVI which reached only 38 points.

As regards cycling no action has been taken during the last years. The Sidewalk Width Indicator may beconsidered good, although the ideal 2 m and half measure was not observed in the areas where the researchwas carried out. Less appropriate situation is presented by the free walking pass indicator– -WPI, which wasequal to 69 points. Several obstacles were found on the sidewalk causing difficulties for the movement ofpedestrians; supports for garbage bags and commercial placards were the most common obstacles. This situ-ation becomes more significant as we observe the poor conditions of the sidewalk ground. Besides these obsta-cles, the inadequate planting of trees on the sidewalk and the lack of adequate pruning also bring aboutenormous difficulties for the pedestrians.

The safety belt use indicator—SBUI and the vertical and horizontal signaling indicator VHSI presentedresults above 70 points, however the 89 points for the safety belt use indicator should receive carefulconsideration.

The high proportion of private motor vehicles per inhabitants in Assis associated with the low standard ofpublic transportation make the more than one person per vehicle indicator—MOPVI present a result equal to38. At last, it was observed that in 2004, the punctuation for the safety belt use indicator—SBUI presentedresults bellow 50 points.

Public campaigns with numerical information combined with other strategies as the creation of visual sym-bols like the five color signaling system may support the decision process of administrators in the area of trans-port and planning. The mobility index amostral may be used as an instrument for the evaluation of themobility conditions in medium sized cities, presenting indicators which depict situations demanding specialattention.

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