CHAPTER 5 Managing Traffic Congestion – The Case of · PDF fileCHAPTER 5 Managing Traffic Congestion – The Case of Land-Use Management and Transport Planning Integration Dr. Werner

CHAPTER 5

Managing Traffic Congestion – The Case of Land-Use Management and Transport Planning Integration

Dr. Werner HeynsArup (Pty) Ltd., Johannesburg, South Africa.

Abstract

Urban structure and transport systems shape each other. Land use and transporta-tion are inextricably linked. It is this linkage that professionals often struggle to understand and subsequently fi nd hard to respond to in ways that balance social and quality-of-life objectives while fulfi lling environmental and economic objec-tives. The results are distorted land-use patterns, urban sprawl and lower densities coupled to growing car use and congestion. Traffi c congestion is increasing, air quality is under threat and time, land and money are being consumed at ever-increasing rates as people carry out their daily activities. Roads play a critical part in meeting our transport needs and supporting our economic objectives. However, urban areas dominated by road infrastructure to accommodate high car usage gen-erally suffer poor amenities, congestion, reduced accessibility and signifi cantly impact on the environment. Not surprisingly, there is a wide range of suggested solutions to these problems: from building new roads to banning cars, and from improving bus services to smart growth strategies, all aimed at infl uencing driver behaviour and travel patterns. More often than not the solutions are not coordi-nated across transport planning and land-use management (LUM) processes as they are implemented by different agencies of government with sometimes mutu-ally exclusive objectives. It is neither desirable to focus on a strictly sectoral approach to implementing such measures, nor is it sustainable to implement a variety of measures on a piecemeal basis in order to address traffi c congestion. Key to managing traffi c congestion in a sustainable way is to develop integrated strategies that cut across supply, demand and LUM measures in forming a bal-anced package. This chapter describes why it is important to integrate transport planning and LUM aimed at road-based, private car traffi c congestion reduction in urban areas. It considers the intrinsic relationship between transport and land use

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84 LAND USE MANAGEMENT AND TRANSPORTATION PLANNING

and why integration is important, before setting out the traffi c congestion theory. It then discusses how we should plan for greater sustainability in land use and transport and the possible solutions or measures that should be adopted as part of this process. Finally, it outlines the circumstances that should prevail before traf-fi c congestion management is implemented and illustrates a possible incremental strategy to address congestion in urban areas.

Keywords: Transport, land use, traffi c, congestion, planning, integration.

1 Introduction

The traditional land use and urban transport planning process have given rise to unsustainable transport systems. Higher car ownership levels, more and longer trips and the provision of less public transport are direct outcomes of traditional planning. This has brought about astronomical community costs in terms of road fatalities and injuries, traffi c congestion, costs to the economy, massive capital investment and environmental degradation. The failure to adequately implement the integration of land use and transport in traditional transport planning in cit-ies has resulted in a declining share of public transport and the ever-increasing dominance of the private cars closely associated with increased emission levels and environmental degradation. As a side effect, the growing road-based traffi c congestion is, therefore, recognised as a major problem as road-user demand con-tinues to outstrip the supply of road infrastructure.

The relationship between land use and transport networks has a fundamental infl uence on the overall level of demand for travel, patronage of various travel modes, accessibility, travel distances and the cost of travel as well as on the ongo-ing cost of providing essential infrastructure and services. The lack of transport and land-use integration and its implementation has indeed had adverse effects on the environment, on people’s welfare and on continued sustainable development.

Despite this negative prognosis, the implementation of a wide variety of land-use and transport measures has attempted to force greater coordination between land use and transport. Three main streams of intervention have evolved over the past few decades and have been applied with varying degrees of success originat-ing from a supply-side paradigm, a demand-side paradigm and LUM initiatives – all having the ability to reduce road-based traffi c congestion one way or another.

As decision makers are increasingly concerned about the environmental impact of planning proposals and as it is considered important to devise approaches to planning that enable joined-up decision making across a variety of sectors, the debates in recent years have focused on policy integration – developing integrated packages to overcome a wide range of transport and spatial planning externalities.

This concept, labelled New Realism, demands that transport and land-use mea-sures and elements of environmental management be integrated in the form of a package approach so as to get the most out of the transport system in accessing spatially dispersed destinations [1, 2]. As it is not sustainable to implement a variety of measures on a piecemeal basis when tackling urban traffi c problems, integration of the measures has been proposed, which encourages the decision


THE CASE OF LAND-USE MANAGEMENT AND TRANSPORT PLANNING INTEGRATION 85

maker to integrate the many measures at his or her disposal forcing greater synergy where the sum of the total impacts is greater than that of the individual impacts.

The diffi culty lies in identifying the right mix of measures appropriate for par-ticular local conditions for inclusion in the congestion-reduction strategy. The developed world has been increasing the use of packages of measures to integrate transport and LUM in a general sense in order to deliver sustainable transport facilities, services and spatial development patterns. However, little has been done to integrate supply, demand and LUM measures when deciding which policy mea-sures are best suited to alleviating site-specifi c traffi c congestion.

Developing integrated strategies aimed specifi cally at reducing road-based traf-fi c congestion is no longer an option in LUM and transport planning, but an essen-tial requirement if traffi c-congestion reduction and sustainable communities are to be left as the legacy of today’s planners. In recent years, growing emphasis has been placed on demand management when dealing with congestion problems, and planners have found themselves hard-pressed to persuade the public that it should pay for a driving privilege, which is perceived virtually ‘free’ and often viewed as an inviolable right. But with mounting pressure from the environmentally con-scious public and with the growing discontent that stems from unconscionably long commute times and growing concerns over simply carrying on ‘building our way out of congestion’, the tide of public opinion seems poised to turn.

This chapter describes why it is important to integrate transport planning and LUM specifi cally aimed at road-based, private car traffi c congestion reduction in urban areas. It considers the intrinsic relationship between transport and land use and why integration is important, before setting out the traffi c congestion theory. It then discusses how we should plan for greater sustainability in land use and transport and identifi es a menu of measures that should be adopted as part of this process. Finally, it outlines the circumstances that should prevail before traffi c-congestion management is implemented and outlines a possible incremental strat-egy to address congestion in urban areas.

2 LUM and Transportation Interaction

Land use and transportation are inextricably linked. A fundamental axiom in trans-port planning is that of transportation being a ‘derived demand’, i.e. people rarely ‘consume’ transportation for the pleasure of movement per se, but rather travel in order to reach opportunities (social, leisure and economic interaction) available at destinations [3]. It is this linkage that professionals often struggle to under-stand and subsequently fi nd it hard to respond to in ways that balance social and quality-of-life objectives while fulfi lling environmental and economic objectives. The result is distorted land-use patterns, urban sprawl and lower densities coupled to growing car use and congestion. Developing a clear understanding regarding the link among transport, the economy and land-use development is diffi cult. Asking questions about that relationship challenges a fundamental and obvious assumption: that economic growth, the need for movement and the need to invest to facilitate that movement go hand in hand.



Indeed, the spatial separation of human activities creates the need for mobility and accessibility and the transportation of goods. Because of its pervasive nature it occu-pies a key position in the fabric of modern-day urban conurbations. As a result, the provision and use of transport infrastructure affect and interact with our socio- economical well-being, the economy, the environment, politics and the way in which spatial development occurs. Because of the pervasiveness of transport, the provision and solutions to transport problems have a major infl uence on people’s lives [4].

New transportation infrastructure can help shape land uses by increasing its accessibility and the mobility of its users [5]. For example, on a highway corridor through undeveloped land, a new interchange increases the accessibility of land-use sites in the vicinity, enabling their development. In addition, the new inter-change offers some existing users of the highway network time savings over their current routes and destinations, thereby increasing demand for new development on these sites. These pressures can result in land development, often at quite a distance from the interchange. While the new interchange may represent a trans-port authorities’ good-faith effort to fulfi l its charge of improving mobility, it also produces powerful effects on land use. Other transportation investments produce ‘induced growth’ in similar ways [6].

This growth can then contribute to undesired environmental outcomes. If not managed properly, habitat loss from new greenfi eld development can interfere with ecosystem functions. Losses in open space, increases in the heat-island effect, and greater air pollution from higher amounts of vehicle travel can all degrade human and environmental health and community quality. Of course, transportation investment cannot produce growth absent demand. That demand and the land-use policies that affect it drive land use and resulting impact. Local policies may pro-duce new development, creating new travel demand and taxing the existing trans-portation network. As a result, the transportation agency may be unable to maintain its level of service standards, leading users and the locality to call for expanded capacity. Thus begins again the cycle of new transportation projects that encounter environmental issues.

Therefore, the importance of coordination between transportation and land-use authorities cannot be overstated enough, as decisions by each can affect the other’s ability to carry out its responsibilities. To understand how to achieve real coordina-tion and policy integration, it is important to fi rst revisit briefl y the institutional context and relationship in which LUM and transportation planning take place. The traditional context in which transportation projects are selected and developed and the separate context in which land-use concerns are addressed pose challenges for policy integration. Attempts at better coordination, then, need to respond to these challenges.

3 Institutional Context and Relationship between LUM and Transportation

The institutional contexts and planning processes in which transportation projects are conceived and carried out present particular challenges to addressing land-use



and transport impact. Transport authorities are generally charged with improv-ing safety, and providing or enabling mobility and accessibility, but their success requires coordination between those managing land use and those implementing transport projects. Historically, large-scale transportation project implementation remains a function of national or provincial/state departments of transportation, while responsibility for local transportation system planning has been de-central-ised to local metropolitan or municipal organisations (MMOs). Institutionally, the LUM function also lies with metropolitan or municipal planning organisations (MMPOs).

MMOs and or MMPOs, whose membership derives from local decision makers such as city councils and/or municipalities, are charged with building regional consensus on investment priorities for the regional transportation system, includ-ing where to place the new capacity. Provincial/state departments of transport are then called upon to implement transport projects from those plans, by way of example. This ‘inner tension’ and/or division in responsibility between several lay-ers of government results in non-integration and out-of-tune delivery of policies and projects.

Comprehensively addressing broader regional needs, such as dealing with con-gestion, therefore requires broader and more holistic packages that include prop-erly coordinated LUM, and these cannot be developed or implemented by transportation agencies alone.

4 Why Is Policy Integration Important?

There is a wide range of measures that could be implemented to manage traffi c congestion and they require cooperation among transport and land use manage-ment (LUM) authorities, and between different levels of government. Given the expected increase in car ownership forecast for the next decade or so, the situation is likely to become more serious. This provides the thrust for the identifi cation of optimal and effi cient mechanisms to deal with traffi c congestion, including bet-ter joint-up action among transport and LUM authorities. A coherent integrated approach or integrated strategy to managing traffi c congestion is desperately sought as May and Gardner [7] argue. This begs the following questions:

• What exactly is understood when the term ‘integrated strategies’ or ‘approaches’ are used in the context of this chapter?

• What has been learned from recent international development in policy integration?• How successful is it?

4.1 The meaning and purpose of integrated strategies

To explain what is meant by an integrated strategy it is necessary to refer to the terms ‘integrated’, ‘balanced’ and ‘package’ as the debate over urban transport policy has generated these terms, which in strategic terms are largely synony-mous [8]. Each implies the combination or integration of policy measures into a



package, which is balanced in its treatment of modes, areas or groups of users and their impact. In the context of this chapter, the term integrated strategy describes:

[T]he interaction and synergy between TDM, TSM and LUM as vital components of a management and decision frame-work aimed at sustainable traffi c congestion management.

Integrated strategies should yield collective benefi ts, as opposed to the less-effective and ineffi cient piecemeal implementation of individual measures as has been the case in the past [9, 10]. For integrated strategies to be effective, transport demand management (TDM) cannot simply be an add-on to conventional supply-side highway capacity strategies, but must be incorporated into the policy frame-work where TDM, transport supply management (TSM) and LUM work together to achieve effi cient goal-directed management of transportation systems.

The purpose of integration and integrated strategies must be to achieve a higher performance against the local policy objectives of the strategy that could otherwise not be achieved by the individual measures on their own. Whatever the local policy objectives, the synergy achieved between the integrated packages of measures is the key to success and the identifi cation of measures that might achieve synergy the principal skill in policy development.

4.2 Ideologies supporting integration

With the need to shift from policies that ‘predict and provide’ to demand-manage-ment-oriented policies such as ‘predict and prevent’ as urged by Owens [11] and Goodwin et al. [2] the term New Realism has been coined capturing an emerging consensus over how to approach transport problems. The principal elements of New Realism are those of less reliance on road construction, the adoption of a package of solutions to given problems, and in general terms managing travel demand rather than providing for it.

Although no formal defi nition of New Realism exists, Walton and Shaw [12] suggest that the concept can be described against its primary objectives, namely:

1. Removing traffi c congestion and improving mobility and accessibility through demand management

2. Implementing measures designed to change or modify the capacity of road networks

3. Altering the spatial distribution of land use attracting an excessive volume of traffi c

4. Combating urban sprawl

Essentially, New Realism predicates that the best approach to solving traffi c-congestion problems is through a coherent package approach providing the scope and mechanism to connect TDM, TSM and LUM. This prescription is based on the consideration that it is no longer possible to solve traffi c problems by adding to network capacity following a supply-side paradigm, causing congestion to migrate to other sites increasing traffi c pressures there. The message is clear – building our



way out of the traffi c congestion problem will most certainly not address the causes of congestion. Investment in the construction and maintenance of new roads may well increase capacity, but induced traffi c arising from latent demand as well as displaced traffi c may simply neutralise its impact.

Critics suggest the underlying solutions that New Realism brings to the fore are not new – however, they do provide a set of mechanisms for tackling transport problems in a more integrated way, which could be translated as a new paradigm for transport planning – an argument supported by Masser et al. [13] and Marvin and Guy [14].

Another ideology that supports the notion of integrated strategies is that of Smart Growth. Table 1 illustrates some Smart Growth strategies.

Proponents of Smart Growth discourage urban sprawl, advocating the use of smart techniques in integrating LUM and TDM, thereby creating a more sustain-able urban environment. Although no single defi nition of Smart Growth exists, several common themes are noted. Proponents believe that Smart Growth should reduce urban sprawl through better land-use and transportation planning. Miller and Hoel [17] suggest that it focuses on development that serves the economy, enhances communities and protects the environment as an antidote to suburban sprawl in an effort to reshape urban and suburban growth. Along the same strand of thought, Smart Growth is described by Litman [15] as a set of complementary TDM and LUM strategies that vary depending on the needs of a specifi c situation.

In comparing Smart Growth, New Realism and Integrated Strategies, Table 2 shows that New Realism and Smart Growth support the common goal of enabling strategy integration because it shares to a large extent the same general policy goals and it is compatible with the broad objectives and principles of integration.

4.3 Recent developments in policy integration

The development of integrated transport strategies has been based on the identifi -cation of the synergy between transport policy instruments. Similarly, the devel-opment of integrated TDM, TSM and LUM strategies are based on the synergy among transport planning, land-use planning and demand management principles. The interaction among spatial planning, transport demand and supply manage-ment policies on the one hand and the conception, operation and management of transport systems on the other is well known and accepted in both scientifi c and professional circles [18, 19]. The danger lies in the strictly sectoral approach to implementing TDM, TSM and LUM policies [20]. While it is possible to formu-late feasible integrated strategies, very few studies have been able to demonstrate that transport or planning policy measures alone will achieve a sustainable situa-tion or indeed reduce traffi c congestion.

In recognising the problem there has been growing interest in the United King-dom in recent years in the development of integrated transport strategies [18]. The UK Transport White Paper ‘A New Deal for Transport’ and subsequent ‘daughter documents’ have signalled the need for an overhaul of transport policy in the



Table 1: Smart Growth strategies.

Strategy Description

Parking management Encourage shared parking and other parking management strategies

Create a network of interconnected streets

Keep streets as narrow as possible, particularly in residential areas and commercial centres. Use traffi c calming to reduce excess traffi c speeds

Site design and building orientation

Encourage buildings to be orientated towards city streets, rather than set back behind large parking areas

Improve non-motorised travel conditions

Encourage walking and cycling by improving pavements and footpaths

Strategic planning Establish a comprehensive community vision that individual land-use and transportation decisions should support

Create more self-contained communities

Locate a variety of land uses within proximity of each other

Encourage quality, higher-density development

Eliminate unnecessary restrictions on density. Demand high-quality designs that address problems associated with higher density

Encourage cluster development

Keep clusters small and well defi ned, such as ‘urban villages’ with distinct names and characters. Coordinate development to facilitate accessibility

Encourage infi ll development

Encourage redevelopment of existing facilities and neighbourhoods

Concentrate activities Concentrate commercial activities in ‘nodes’ of high-density, mixed development linked by freight service

Flexible zoning Reduce excessive and infl exible parking and road capacity requirements

Encourage public transport–oriented development

Increase development density around public transport hubs and high-capacity public transport corridors. Provide good walking and cycling facilities in those areas

TDM Use transportation demand management to reduce total vehicle traffi c and encourage the use of effi cient modes

Preserve green space Preserve open space, particularly areas with high ecological and recreational value. Channel development into built-up areas

Encourage a mix of housing types and prices

Develop affordable housing near employment, commercial and transport centres

Storm water management

Encourage on-site storm water drainage and water conservation

Source: Litman [15] and Victoria Transport Policy Institute [16].



Table 2: Comparing the goals, objectives and principles of Smart Growth, New Realism and Integration.

Intervention Smart Growth

New Realism

Integration

GoalSustainable development * * *Economic prosperity * * *Community enhancement * *Coordinated planning * * *

Broad objectivesEffi ciency in the use of resources *Safety in design of infrastructure * * *Improved accessibility and mobility * *Environmental protection * * *Integrating transport and planning measures * * *Financial feasibility * *Foster economic growth * * *Congestion reduction * * *Combating sprawl * *Raising revenue *

Fundamental principlesCreate range of housing opportunities and

choices*

Encourage community and stakeholder collaboration

* *

Foster distinctive, attractive communities with a strong sense of place

*

Make development decisions predictable, fair and cost effective

* *

Mix land uses * *Preserve open space and environmental areas * *Social progress that recognises the needs of

everyone* *

Effective protection of the environment, limiting global effects

* * *

Prudent use of natural resources *Maintain high levels of economic growth and

employment* *

Predict and manage * *Provide a variety of transportation choices * * *Strengthen development in existing

communities*

Compact building design *Create walkable neighbourhoods * * *

Source: Author’s own construction.



United Kingdom [7, 21]. The European Commission [22], Ministry of Transport, Public Works and Water Management [23] and the US Department of Transporta-tion [24] report parallel developments in Europe, the United States and elsewhere having signalled the urgency and need for more sustainable and integrated trans-port systems against the background of fi ve common themes emerging in the inter-national debate over the way forward in reducing congestion. These are:

• Better planning of transport infrastructure and making more effi cient use of existing infrastructure;

• Reducing dependence on the car, especially in towns; empowering local deci-sion making;

• Switching emphasis on spending from roads to public transport;• Stronger action on the implementation of LUM and transport planning integration;• Reducing the impact of road freight.

Over the last couple of decades, the concept of integrated strategies for urban areas and the means of evaluating them have been developed and accepted into practice by major UK studies of cities such as London [7], Birmingham [25] and Edinburgh [26]. Many other success stories also exist, most notably Toronto, Van-couver, Singapore and Curitiba. These experiences demonstrate that when an inte-grated approach in which infrastructure provision, management of existing infrastructure and the pricing of the use of that infrastructure are co-ordinated with LUM, the scale of urban transport problems can be signifi cantly reduced.

4.4 Integration in practice

This section shows how various policy measures and initiatives have been con-sidered and implemented in the past in addressing traffi c congestion refl ecting signifi cant international differences in the ways countries perceive and respond to congestion problems. It will demonstrate the types of integration implemented and how they have been implemented with varying degrees of success. It highlights the sectoral approach to implementing TDM, TSM and LUM measures, referencing typical examples forming the argument for the desperate need to integrate TDM, TSM and LUM measures into a package approach [27–32].

4.4.1 Non-integrationThe World Bank has reported that cities in the least developed countries and in developing countries have an inability, for whatever reason, to plan transport sys-tems, to manage travel demand, to relate land use and transport and to provide adequate resources for transport. Consequently, cities in developing countries suffer from some of the following common transport problems, as described by Cracknell [33]:

1. Increasing traffi c congestion,2. Declining attractiveness of road-based public transport,



3. Increasingly high costs of travel,4. High levels of (road) accidents, and5. Increasing road traffi c–related emissions and atmospheric pollution.

Barredo and Demicheli [9] add that the transport management practices in the cities of less-developed countries and developing countries, which are becoming the engines of economic development, are woefully inadequate, with functional or modal integration and transport and planning integration not occurring on a wide-enough scale. Many of these countries believe that improvements in the operation and performance of the transport system per se will provide the necessary thrust to combat traffi c problems and they attach no benefi t to the implementation or con-sideration of full integration with TSM, TDM and LUM measures or they fi nd it diffi cult to fund such undertakings.

4.4.2 Partial integrationThe developed world has had more success in integrating TDM, TSM and LUM measures. Stewart and Pringle [34] report that Toronto and Vancouver in Canada have been able to achieve an enviable level of public transport use as a result of historical success in maintaining an effective public transport system and in integrating public transport policies with LUM. Verhetsel [35] reports that a num-ber of planning and infrastructure measures have been implemented in Antwerp (Belgium) aimed at alleviating traffi c congestion. The measures implemented are predominantly TSM and LUM measures within the functional or modal integra-tion and transport and planning integration context.

Work for the European Commission, studying optimal transport strategies in nine cities, has demonstrated the importance of an integrated package of measures, including fi scal controls on car use, changes in public transport frequency and fares, vertical integration, horizontal integration and low-cost improvements in infrastructure [36]. It has also been demonstrated that, in six of these nine cities, the revenue stream from the fi scal controls on car use would be more than suffi -cient to fi nance the remaining elements of the strategy. This demonstrates the effectiveness of combining TDM and TSM measures.

Halden [37] reports the successful application of access management aimed at integrating land-use and transport policies in Edinburgh and the Lothians in Scot-land as an example of partial integration. There are also indications of LUM suc-cesses in Korea in imposing development restrictions that have resulted in clustered demand around Seoul, special land assembly in Shanghai and Bombay and new cluster development in Bangkok aimed at reducing congestion [38].

4.4.3 Full integrationSim et al. [39] report the successful integration of TDM, LUM and TSM in Singa-pore and how it has alleviated severe traffi c congestion thanks to its comprehen-sive and highly integrated policy measures. The only other two cities experiencing similar success are Curitiba (Brazil) and the Lao People’s Democratic Repub-lic [40, 41]. Their success lies in comprehensive and highly coordinated land



transport policies combining the integration of land-use and transport planning with demand management measures. This has the effect of maximising the bene-fi ts from the transport system, providing the best opportunity for more sustainable transport and a better environment, creating a fairer and more inclusive society.

In summary, Section 4 has highlighted that transport policy and implementing authorities must engage increasingly with other sectors to deliver a truly integrated approach and move towards a New Realism in transport employing Smart Growth principles in the formulation of such strategies. It has also demonstrated that such an approach has had varying degrees of success – the rate of success is greater though in the developed world.

5 What is Traffic Congestion?

If we want to address traffi c congestion, we fi rst need to understand what traffi c congestion is. And indeed, there is no single, broadly accepted defi nition of traffi c congestion. One of the principal reasons for this lack of consensus is that conges-tion is both:

• A physical phenomenon relating to the manner in which vehicles impede each other’s progression as demand for limited road space approaches full capacity.

• A relative phenomenon relating to user expectations vis-à-vis road system performance.

Urban traffi c congestion must be understood in the wider context of city dynam-ics and agglomeration benefi ts. Traffi c congestion in urban areas is often the out-come of successful urban economic development, employment, housing and cultural policies that make people want to live and work relatively close to each other and attract fi rms to benefi t from the gains in productivity thus derived. There are many indications that, even though they may not be thrilled by the prospect, urban road users are prepared to live with crowded roads as long as they derive other benefi ts from living and working in their cities.

Congestion prevents us from moving freely and it slows and otherwise disrupts the conduct of business within urban areas. However, it is important to note that unfettered movement is not the primary benefi t we derive from living in urban areas. Cities provide access to a wide range of activities, people, services, goods, markets, opportunities, ideas and networks. These benefi ts can be delivered either through speed or through greater proximity. Congestion may affect travel speed but in some circumstances, such as dense urban cores, congestion may both be expected and, to some degree, accepted. In these cases, cities have come to accept a degree of conges-tion and continue to get along relatively well as long as overall accessibility is high.

Most commonly, traffi c congestion is referred to as a situation where ‘demand for road space exceeds supply’. The European Conference of Ministers (ECMT) defi nes traffi c congestion as:

Congestion is the impedance vehicles impose on each other, due to the speed-fl ow relationship, in conditions where the use of a transport system approaches its capacity.



This defi nition still focuses on the proximate causes of congestion, i.e. too much demand for a particular segment and/or segments of the road network. This expla-nation begs a greater question: Why is the volume of traffi c swamping the road infrastructure at that/those particular time(s) and place(s)? This is a question to which there are no easy and/or obvious answers and relates to expectations.

The inherent diffi culty in capturing user expectations renders the precise quan-titative defi nition of congestion a diffi cult, if not impossible, task. In this respect, as the US Federal Highway Administration notes:

Congestion is essentially a relative phenomenon that is linked to the difference between the roadway system performance that users expect and how the system actually performs.

Users’ expectations regarding road system performance, therefore, are central to understanding how congestion is perceived and defi ned. The same levels of traffi c might be perceived as either intolerably congested or acceptably slow according to where and by whom it is experienced. Road users in rapidly expanding cities might share the former view while those travelling on the roads of large mature conurbations might share the latter.

5.1 The speed–flow relationship

Clearly then our perception of traffi c congestion is infl uenced by factors including perception and expectations. But how does traffi c congestion start?

To answer this question, one has to consider the speed–fl ow relationship. The relationship between speed or travel time and fl ow is fundamental to the under-standing of congestion [42]. Failure to understand this relationship correctly may result in inaccurate conclusions and misconceptions. Indeed, there is considerable confusion and dispute in the literature concerning the appropriate use of the speed–fl ow relationship to evaluate, for example, the implementation of road pricing or other TDM measures. The disputes are best represented by debates between Evans [43] and Hills [44].

The theoretical argument used to explain the speed–fl ow relationship is shown in Fig. 1.

It illustrates a relationship that is well founded in economics and transport lit-erature [45–49].

It begins by considering a homogeneous traffi c stream moving along a given stretch of urban road with fi xed beginning and end points. The traffi c stream would be able to achieve a speed that balances the benefi ts of a faster trip against the costs of a trip with higher energy requirements and a greater risk of an accident. Ceteris paribus, as other vehicles enter the road thereafter, density increases, speed drops and travel time (or delay) lengthens (and accident probability rises). The causality is as follows: traffi c density determines speed and not vice versa. Paralleling the theory of fl uid dynamics, traffi c fl ow is the product of density, in vehicles per kilo-metre and speed in kilometres per hour, with traffi c fl ow attaining a maximum at Fmax with speed at Sm in Fig. 1b [45].



As additional vehicles join the traffi c stream, the volume of traffi c grows and hence the demand for road space. This phenomenon increases the demand beyond Fmax onto the backward bending part of the speed–fl ow curve towards the origin on the horizontal axis. Intuitively, traffi c congestion develops and rapidly worsens and may cause ‘traffi c-jams’ at times. As travel demand diminishes towards the end of rush hour, the demand for road space decreases and traffi c fl ow returns to the upward sloping part of Fig. 1b.

5.2 What is it that congestion prevents us from accomplishing – why is it ‘bad’ for our cities?

By asking the question ‘what is it that congestion prevents us from accomplish-ing?’ it is possible to understand why it is considered ‘bad’ for our cities and, hence, why it requires management or control.

Figure 1: Speed–fl ow relationship. Source: Hau [45].



Transport systems facilitate the rapid and predictable movement of people, vehicles and goods. Congestion, on the other hand, prevents traffi c from mov-ing freely, quickly and/or predictably. However, the benefi ts afforded to us by transport activity stem not from mobility itself, but, rather from what that mobility allows us to accomplish. Most daily travel is not undertaken for its own sake. Rather, in almost all cases, people travel to access activities, people and services, and goods travel to reach markets. Mobility, by itself, is generally considered not to have an intrinsic value but, rather, is often viewed as a derived demand. What value (and benefi ts) mobility delivers lies in the activities that mobility enables.

The question posed above therefore has two answers. A fi rst answer therefore to the question is that it prevents us from moving freely and the second is that it reduces the time those affected have available to undertake activities – including ‘productive’ activities. It reduces the time we have to undertake other activities by either making travel longer through queuing or by imposing additional time ‘buf-fers’ to ensure that scheduled activities are not impacted by unpredictable travel times. The complex issues of ‘time loss’, economic impact, loss in productivity, travel delay and schedule delay have an important bearing on our understanding of how is it that congestion negatively impacts society.

5.3 The economic logic of managing traffic congestion – the case for road pricing

Having explained the speed–fl ow relationship as well as what traffi c congestion prevents us from accomplishing and/or why it is ‘bad’ for our cities, let us turn to considering the economic logic of managing traffi c congestion. This will be explained in the context of how road pricing, as an economic instrument, reduces traffi c congestion, hence connecting economic principles to transport theory. The economic logic or rationale in favour of road pricing is not controversial and has been documented by a number of authors. The modest aim here is to introduce the reader to the economic justifi cation for charging motorists, or indeed applying TDM measures to reduce traffi c levels to a socially optimal level.

The individual motorist incurs journey time and money costs when he under-takes a journey. The money costs are the fuel and other vehicle operating costs associated with the journey. Under congested conditions, the time and money costs may be very substantial. However, the motorist will nevertheless undertake the journey if the value he derives from it outweighs the costs [46,49–51].

Under congested conditions, an additional vehicle on the road imposes costs on other road users. This is largely because each vehicle on the road reduces the speed of other road users. If the value to the motorist undertaking the journey is less than the sum of his own journey cost and the journey costs imposed on others, then road users as a whole are worse off. If a price were charged to use the congested road network equal to the cost imposed on other traffi c, the motorist would only use the road if the value of the journey exceeded the sum of the charge and his other jour-ney costs. This would deter additional trip-making when the costs to society as a whole exceeded the benefi ts. The excess travel that produces congestion costs may



also give rise to other external costs such as air pollution, noise and accident costs. Hence, the price to be charged should refl ect the overall social cost of congestion, environmental damage and accidents. Figure 2 demonstrates these points.

To arrive at Fig. 2, the speed–fl ow curve is converted into a travel time–fl ow curve. The speed–fl ow curve (see Fig. 1b) can be straightforwardly converted to a travel time–fl ow curve as travel time is the reciprocal of speed, with vehicles-kilometre per lane-kilometre-hour on the horizontal axis (see Fig. 1c). Using a constant value of time as a shadow price for the representative traffi c stream, travel time is then converted to a money basis, which yields time cost (P), presented on the vertical axis of Fig. 2.

Figure 2 then goes on to illustrate the economic logic of road pricing. Traffi c volumes (V) are shown on the horizontal axis and the cost of travel, the time and money costs for making the journey (generalised cost) are plotted on the vertical axis. The demand for travel is represented by curve DD. This indicates that as journey costs rise, demand for travel falls. The marginal social cost (MSC) curve S2 shows the additional costs imposed on all road users, as traffi c volumes rise. The average variable cost, also known as marginal private cost depicted by S1 (AVC/MPC), on the other hand, shows the costs incurred by each individual trip-maker.

Low traffi c volume corresponds to relatively high speed; so fuel costs would be high. With high traffi c fl ow and low speed, however, the fuel costs would be high because of fuel ineffi ciencies caused by the alternate acceleration and deceleration associated with dense traffi c. These two factors roughly cancel one another out leading to the plausible assumption that the costs of operating a vehicle (which includes fuel, oil, maintenance and depreciation costs) are approximately indepen-dent of the level of traffi c fl ow [45]. A fi xed money cost for the vehicle operating cost can therefore be added to the time cost portion to form the generalised

Figure 2: Principle of congestion pricing. Source: Li [46].



cost – an accepted construct of transport economics [52]. Similarly, the road’s variable maintenance cost, which is assumed to be proportional to the traffi c level, can also be calculated. Hence, the time cost element is mainly responsible for the upward-sloping portion of the AVC curve (S1).

When traffi c volumes reach a certain level, both marginal cost curves rise because network speeds reduce. This occurs as a result of vehicles slowing one another down, which increases the generalised cost of trip-making, because at slower speeds, journeys take longer and the vehicle cost rises as drivers engage lower gears and begin to stop or start frequently to allow for movement through the congested road.

The individual trip-maker bases the decision to travel on his marginal private cost and the value of the trip to him [45]. Hence, the trip-maker will undertake the journey if the benefi t he would receive from making the journey outweighs the cost of the trip borne by him. In Fig. 2, an equilibrium is reached at price P1 and traffi c volume V1 at h. Point h, however, does not refl ect the optimal traffi c fl ow; as curve S1, the MPC curve does not take into account the congestion costs imposed on other road users by the marginal motorist [46].

Every motorist only considers the actual level of congestion on the road when deciding whether to make a trip. He or she does not realise that by making a trip he or she adds to the congestion and further slows down the existing traffi c. The difference between the MSC and the MPC is the congestion cost caused by the additional vehicle. At traffi c volume V1, the MSC of the traffi c exceeds the mar-ginal benefi ts. In other words, there is excessive congestion imposing marginal costs on other motorists in excess of the benefi ts gained by a marginal driver. Put differently, the road is being consumed beyond the point of maximum effi ciency or optimality [49].

However, the optimum or effi cient traffi c volume is at V2 where the MSC and demand curves meet at e. The additional traffi c volume (V1 – V2) imposes costs of V2egV1 but yields benefi ts of V2ehV1 only. The net loss arising from the additional traffi c is therefore defi ned by the area egh. Hence, only at traffi c fl ow V2 is the demand for road space equated to the full marginal costs of using it. Any volume of traffi c above V2 implies that the social cost of trip-making exceeds the benefi ts gained and is associated with a negative externality. This is the cost imposed on motorists not directly responsible for the congestion but who have an external social private expense as a result of the additional cost imposed on them [52].

The real problem lies in making the motorists aware of the congestion costs they impose on others and to reduce the traffi c volume to the level V2. In order to restrain traffi c to the socially optimal level V2, a road pricing charge equal to (P2 – P3) is needed. The charge then ‘internalises’ the externality by adjusting the marginal private cost so that the user considers the actual benefi ts of the cost of his decision to travel and ultimately reduces the congestion level to the optimal level V2. The charge or Pigovian tax of (P2 - P3) would dissuade motorists from undertaking certain road journeys and, as a result, the demand for scarce road space is matched by the available supply [54, 55].



The down side to the congestion charge is that, although it seems ideal in theory, it is diffi cult to administer because, for the government to set its congestion charge at an optimal level, it must know the exact amount of the externality in order to reduce the traffi c levels to the effi cient level. As governments do not have full information on this issue, their accurate judgements will have to suffi ce. Hyman and Mayhew [56] state that if the charge is sub-optimal, only a few users will be priced off the roads and there will be no congestion relief. Should the charge be excessive, too many users may be priced off and there would not be enough remaining users to benefi t from the reduced congestion.

This obviously means that the Pigovian tax solution is unlikely to lead to an effi cient traffi c level on its own. This is one of the reasons why an integrated approach in transport planning and LUM is required to help manage traffi c congestion.

6 Planning for Sustainability in Land Use and Transport towards Integrated Strategies

When designing optimal integrated strategies, sustainability is a key issue in the approach to and considerations of planning [57]. Sustainability should be the end product of interacting components within the planning process. It is therefore essential to be clear about what the strategy is it designed to achieve. Within the vision of identifying solutions to address traffi c congestion and to achieve sus-tainability, there is, not surprisingly, a wide range of suggested solutions to the problem. There is however also a danger that politicians and, in some cases, pro-fessionals immediately assume that a particular solution is needed without truly understanding the magnitude of the problem. It is essential that decision makers are clear about the reasons for such solutions: i.e. that the objectives which are to be achieved can be specifi ed and measured against an overall predetermined vision. This is precisely why Himanen et al. [58] argue that decision makers have to take account of specifi c considerations and must have a clear vision of what their proposed integrated strategies are to achieve.

Once a clear vision of the problem has been formed and the general idea of solv-ing it has been conceptualised, the decision maker is interested in a further funda-mental question – i.e. ‘when are the integrated strategies sustainable?’ The answer and connection may lie in the assessment made by Banister [10], suggesting that the measurement of sustainability be used as a mechanism connecting the sustain-ability objective with the derivation of sound planning considerations. Conversely, a mechanism or process is required to measure or evaluate the level of sustainabil-ity achieved by the integrated strategy in reducing traffi c congestion. From this point of view, the following sub-sections provide an outline of:

• The considerations to be included in a logical approach to ensure that integrated strategies contribute to sustainable development.

• How to measure or evaluate the level of sustainability achieved by integrated strategies developed to reduce traffi c congestion.



6.1 Problem identification

The fi rst consideration according to May et al. [26] is that of identifying the prob-lems. There are in practice two different types of approaches that can be adopted to identify problems and indeed also objectives. The fi rst is the true objective-led approach and the second is the problem-oriented approach. With the objective-led approach, detailed objectives are fi rst specifi ed – being a range of specifi c objec-tives that will help contribute to the main strategic objective of reducing traffi c congestion. These are then used to identify problems by assessing the extent to which current, or predicted future conditions, in the absence of new policy mea-sures, fail to meet the objectives. This approach has been adopted in many ‘so-called’ integrated transport studies [59].

Both methods (objective-led and problem-oriented) converge at the stage of option development using these as a basis for identifying solutions and strategies. In either case, it is essential to be comprehensive in the list of types of problems. Neither of these approaches is necessarily preferable to the other.

6.2 Specifying objectives

Regardless of which approach is used, the objectives specifi ed are broad state-ments of the improvements that a city is seeking in its land-use and transport system, specifying the directions for improvement, but not the means of achieving them. In being clear about what the integrated strategy is designed to achieve, clear policy objectives are required [60, 61]. The formulation and development of such objectives must incorporate the characteristics or components of our understand-ing of what we believe sustainability will achieve and to incorporate those into the decision-making processes [60]. Such objectives will allow the decision maker to measure the extent to which his or her integrated strategies will contribute to transport and development sustainability in serving the following key functions:

• Identify problems to overcome, both now and in the future;• Provide guidance on the appropriate types of solution and the locations in

which they are needed;• Act also as constraints, in clarifying what should be avoided in pursuing any

particular solution;• Provide the basis for appraisal and monitoring progress of alternative solutions.

The following seven objectives are to be used as a guide when measuring the extent to which integrated strategies contribute to sustainable development, while discouraging traffi c congestion as the main strategic objective [18, 19]:

• Economy;• Protection of the environment;• Liveable streets and neighbourhoods;• Safety;



• Equity and social inclusion;• Accessibility;• Integration.

6.3 Selecting criteria

Because the sustainability objectives identifi ed earlier are abstract concepts, it is diffi cult to measure performance against them or the contribution made by every measure (TDM, TSM and LUM) in meeting them. It is not possible to satisfy all the objectives that may be desirable to achieve a given strategy as cited by Jones and Lucas [60]. For example, it is often diffi cult to improve accessibility without intruding upon the environment. It will consequently be useful to trade-off per-formance against different objectives, so that these confl icts can be more easily resolved. To do this, impact criteria are required to measure the various options/measures’ contribution to meeting the sustainability or policy objectives. In other words, such impact criteria are required to measure the extent to which integrated strategies contribute to sustainable development. Each criterion must be measur-able, in the sense that it will be possible to assess, at least in a qualitative sense, how well a particular option/measure is expected to perform in relation to the cri-teria (and associated indicators). Table 3 provides a list of commonly used criteria when assessing objective achievement.

6.4 Selecting indicators

Objectives and criteria generally indicate the desired general direction of change, e.g. to reduce the environmental nuisance caused by traffi c. Indicators are required to inform the decision maker about the extent to which selected measures contribute to meeting the sustainability objectives, and their use is a very effective way to encour-age action and monitor performance. The purpose of indicators is threefold [62]:

• They either evaluate the effectiveness of objectives at the outset of a program or project, or

• Monitor progress of implemented policies towards policy goals and objectives, or• They assess the outcome of policies in terms of these objectives.

It follows that indicators can subsequently be classifi ed as input indicators, pro-cess indicators and output indicators. In the context of this chapter, output indica-tors are more appropriate as they measure the outcome or impact of proposed integrated TDM, TSM and LUM measures as opposed to process indicators that evaluate and monitor the actual progress and processes that lead to the end results.

A large number of indicators are needed to properly assess the multi-dimensional nature of sustainable development as the framework of indicators must contain indicators for respective categories, whether they are for project phases, environ-mental or sustainable development themes or other dimensions. Based on voluntary national testing and expert group consultations, the Spatial Development Initiative



(SDI) task force developed an indicator framework of 58 indicators and methodol-ogy sheets for all countries to use, which is suited to country-specifi c conditions and makes indicators of sustainable development accessible to decision makers at the national level [63].

It must be recognised that any framework, by itself, is an imperfect tool for organising and expressing the complexities and interrelationships encompassed by sustainable development [64]. There is no universal set of indicators that is equally applicable in all cases. Ultimately, the choice of a framework and a core set of indicators must meet the needs and priorities of users, civil society groups and decision makers responsible for the development and use of indicators to monitor progress towards sustainable development.

The current set of indicators developed by the SDI task force allows integrated evaluation of sustainable development according to four interrelated components as illustrated by Fig. 3.

Table 3: List of objectives and associated criteria.

Objectives Criteria

Economy Implementation costVehicle operating cost

Journey time reliability

Economic effi ciency

Economic growth

Liveable streets and neighbourhoods

Safe and secure neighbourhood

Freedom of movement

Protection of the environment Emission level

Urban sprawl

Visual intrusion

Equity and social inclusion Contribution to investment in transport

Access to public transport

Community cohesion

Safety Accidents

Danger

Intimidation

Integration Transport interchange

Impact on traffi c congestion

Accessibility Ease of reaching opportunities

Community severance

Access to the transport system



When the Spatial Development Initiative Framework (SDIF) [64] is compared and related to commonly used industry indicators in land-use development and transport planning, it is possible to decompose the SDIF dimensions and its associ-ated indicators and transpose them into 24 elements or concerns as illustrated by Table 4. Each element refl ects a key concern of sustainable transport and spatial development.

Figure 3: Components of sustainable development.

Table 4: Decomposing dimensions, elements and concerns.

Environmental dimension

Societal dimension

Economic dimension

Institutional dimension

Limiting emissions

Meeting access needs of individuals

Affordability Effective institu-tional framework

Limiting waste Meeting access needs of society

Effi cient operation

Institutional capacity

Minimising consumption of non-renewable resources

Access needs are met consistent with ecosystem health

Choice of transport mode

Need for a national sustainability strategy

Limiting con-sumption of renewable resources

Access needs are met consistent with human health

Support for a vibrant economy

Reusing and recycling of components

Access needs are met safely

Distance travelled by mode

Minimising land use

Access needs are met with equity within this generation

Journey time

Minimising noise Access needs are met with equity across generations

Journey cost

Source: United Nations [64].



It follows then that it is possible for each concern or element to be refl ected in output indicators measuring the extent to which selected measures contribute to meeting the sustainability objectives highlighted in Table 3. The output indicators can be straightforwardly related to specifi c criteria associated with each objective such as those conceptualised in Table 5.

Because of different planning approaches, objectives and national and regional policies implemented in the least-developed, developing and developed countries, the potential exists for the output indicators to differ signifi cantly [38]. The indica-tors shown in Table 5 are therefore a useful starting point in evaluating the effec-tiveness of integrated strategies aimed at traffi c-congestion reduction.

Table 5: Objectives, criteria and output indicators.

Objectives Criteria Indicator

Economy Implementation cost High

Vehicle operating cost Medium

Journey time reliability Low

Economic effi ciency Cost Benefi t Analysis (CBA)

Economic growth

Liveable streets and neighbourhoods

Safe and secure neighbourhood

Freedom of movement

Number of accidents involving pedestrians/cyclists and cars

Accidents by location, mode and victim

Protection of the environment

Emission level Reduction in emission levels

Urban sprawl Visual intrusion

Visual intrusion Noise

Land take

Equity and social inclusion

Contribution to invest-ment in transport

Increased accessibility to public transport services

Provision of public transport

Losers and winners by income and category

Community cohesion Close proximity of demand-driven land-use functions reducing travel time and distance

Safety Accidents Less traffi c accidents

Danger Residential design that makes people feel safe

Intimidation

(Continued)



Table 5: Objectives, criteria and output indicators (Continued).

Objectives Criteria Indicator

Integration Transport interchange Increased land-use mix and clus-tering

Impact on traffi c conges-tion

Reduced total vehicle miles of travel (VMT) on congested roads

Reduced total vehicle hours of travel (VHT) on congested roads

Reduction in distance travelled to leisure, work, shopping and education destinations

Mode shift

Accessibility Ease of reaching oppor-tunities

Reduced average time and cost to all activities of a given type from a specifi ed origin by a specifi ed mode

Community severance Increased access to the transport system

Access to the transport system

Source: Reconstruction of United Nations [63], Commission of European Communities [62] and O’Flaherty [4].

6.5 Transposing sustainability dimensions into components relevant to planning

To ensure that the Brundtland Commission’s defi nition of sustainable develop-ment fi nds widespread acceptance, it is both vague and simple enough to include a variety of divergent interest groups. Sustainable development is ascribed to by just about every single nation-state, irrespective of its democratic credentials, eco-nomic strength or political system. More fundamentally, sustainability has become the raison d’être and ideal of spatial development.

The source of this almost universal appeal can be found in the highly elastic core ideas that fl ow from the Brundtland defi nition. Underlying this defi nition is the assumption that balancing the three pillars of sustainable development – eco-nomic development, environmental integrity and social well-being – is attainable and that sustainable development arises when economic, social and environmental objectives are realised simultaneously. This is not always possible and trade-offs become necessary primarily through political or institutional debate, thereby add-ing a fourth dimension to the achievement of sustainability. Subsequently, societ-ies formulate development objectives and strategies that move the dimensions in the direction of partial or full overlap (integration) as illustrated in Fig. 4.



Integrated strategies must encourage and facilitate the movement of the dimen-sions of sustainable development towards full overlap. To understand how these dimensions are related within the planning system, it is necessary to reformulate them into more transformative ends. By transposing the dimensions, the following interrelated components relevant to planning are identifi ed:

• The planning system supported by an institutional framework that considers and promotes economic growth and social well-being,

• The menu of policy instruments that helps attain sustainability and forms the underlying components of strategy integration,

• The environmental management framework within which planning decisions are made,

• The requirement of effective public participation refl ecting the public mood and the sentiments of other stakeholders in the development process,

• A funding framework,• An appraisal framework assessing the impact of proposed planning policies.

These are all the necessary components and/or ingredients of the planning sys-tem that help decision makers arrive at consistent and concise decisions about traffi c-congestion reduction that supports sustainable development.

7 Menu of Measures

Land-use and transport planners have available to them, at least in principle, a wide range of measures to infl uence development and transport policy. This can be advantageous in that it provides a high degree of choice and fl exibility. The mea-sures or instruments are the means by which policy objectives can be achieved and problems overcome forming an integral part of strategy development. According to the Department for Transport [65], the policy measures fundamentally infl uence the performance of the transport system by changing:

1. The demand for travel,2. The supply of transport facilities, and3. The cost of provision and operation of the transport system.

Figure 4: Dimensions of sustainable development achieving full overlap.



Although the instruments are categories in several ways, in this chapter, they are dealt with under the headings of TDM, TSM and LUM. These measures provide the decision maker with choices that enables him to improve:

• Urban design to promote travel on foot and by bicycle,• LUM aimed at reducing private vehicle travel,• Public transport options,• Vehicle and traffi c management technologies to reduce the impact of car journeys,• Alternatives to travelling,• Accessibility and mobility.

The implementation of policy measures will impact on the urban area in which they have been put to use and it is quite possible that there will be a unique reaction to them [66]. It is important to consider the effects of every measure as part of the decision-making process, as it is the effects of each measure that infl uence driver behaviour, generalised cost, trip characteristics and ultimately congestion levels. It is therefore essential to appraise, evaluate and understand each measure not only in terms of how well it achieves sustainability objectives or the broad objective of congestion reduction, but also their effects. The sub-sections below highlight some industry standard TDM, TSM and LUM measures available in the decision mak-er’s toolkit.

7.1 Land-use measures

O’Flaherty [4] notes that trip-making patterns, volumes and modal distributions are largely a function of the spatial distribution and use of land. Thus, at individual development sites, exercising control over the trip-generating characteristics of the land-use function (e.g. development density) can be used to make the result-ing demand consistent with existing transportation infrastructure and the level of service desired. To this end, Table 6 shows the land-use measures that have been considered in several metropolitan areas to manage and direct urban growth. In alleviating future congestion, it is therefore essential that LUM measures be con-sidered when developing integrated strategies to infl uence spatial form in conjunc-tion with the strategic planning of transportation services.

7.2 Transportation supply measures

Supply managing the transportation system by adding new capacity or making operational changes to improve system performance has been the most common response to transport- and congestion-related problems for many years [4, 33, 38]. Table 7 illustrates TSM measures categorised by the target group. Inevitably, where new capacity is continually added to accommodate increasing demand to reduce congestion levels, a continued reliance on the private car will be fostered, which in turn gives rise to induced traffi c, sometimes nullifying the increased capacity and having serious implications on the urban mobility options available



in a region [6]. However, on the positive side, additional capacity improvements to accommodate public transport facilities may help alleviate the congestion prob-lem, but the construction of these actions can be very costly and may be met with strong public opposition if funded through the public purse.

7.3 Demand management measures

Managing transportation demand in its broadest sense suggests implementing any action or set of actions intended to infl uence intensity, timing and spatial distribu-tion of transportation demand for the purpose of reducing the impact of traffi c – resulting in more effi cient use of transportation resources [15].

Research by May [69] and Seik [70] suggests that well-conceived and aggres-sively promoted demand management reduction programmes can indeed decrease

Table 6: Land-use measures.

LUM measures

Development densities – involving an increase in density of development throughout an area to reduce the need to travel

Development patterns – including transport corridor-based developments designed to encourage provision and use of public transport

Development mix – in which homes, jobs and shops are placed close together, thus reducing the need to travel

Development conditions – such as parking standards for new developmentCommuted payments, whereby developers can provide less parking but pay for

public spaceDeveloper contributions to the fi nancing of transport infrastructure for new devel-

opmentsValue capture taxes, designed to refl ect the windfall benefi ts to existing develop-

ments from improved accessibilityLand-use taxes – including property taxes.Company travel plansChanges in business taxesLocation relative to public transportInfi lling and control of peripheral developmentSmart GrowthStreet reclaimingClustered land useLocation effi cient development – such as development that maximises multi-

modal accessibilityCar-free planningPedestrianisationSource: Meyer [67], Victoria Transport Policy Institute [15], Department for Transport [8,65], May et al. [21] and Potter and Skinner [68].



Table 7: Transportation supply measures.

TSM measures to get the most out of existing infrastructure

TSM measures to infl uence car use

Incident detection and manage-ment systems

New road construction (grade separation, geometric design)

Ramp metering New off-street parking

Highway information systems New car parks

Providing additional lanes with-out widening the freeway

Parking controls, including controls on dura-tion, entry times and designated users

HOV facilities Road maintenance and improvements

Park and ride facilities Road space reallocation

Super street arterials Conventional traffi c management

Intersection improvements Conventional speed controls and restrictions

One-way streets Urban traffi c control (UTC) systems

Reversible traffi c lanes Intelligent transport systems (ITS)

Arterial access management Accident remedial measures

Streets space management Traffi c calming measures – relates to design features such as roundabouts instead of stop signs

Traffi c-calming measures Traffi c-restraint measures – such as segrega-tion and integration

Alteration of geometrical features Access control or management

Traffi c signal improvements Multimodal transport stops and interchanges

Interconnected and adaptive signal systems

Smart Growth

Arterial surveillance Reversible lanes

Turn prohibitions Physical restrictions

Improved traffi c control devices

TSM measures to infl uence public transport use

TSM measures for cyclists and pedestrians

Upgrades to existing fi xed infra-structure

Cycle lanes and priorities

New rail or bus stations, termi-nals and interchanges

Cycle parking provision

New rail or light rail lines Cycle facilities

New rail services on existing lines Fixed route and express bus services

Pedestrian crossing facilities

(Continued)



Table 7: Transportation supply measures (Continued).

TSM measures to infl uence public transport use

TSM measures for cyclists and pedestrians

Provision of guide busses Pedestrian areas (pedestrianisation)

Park and ride Safe routes to school

Terminals and interchanges

Light rail systems TSM provision for freight

Bus priorities Lorry parks

High occupancy vehicle (HOV) lanes

Transhipment facilities

Timetabling strategies

Bus service management measures designed to improve reliability

Access management

Shuttle services

Source: Meyer [67], Victoria Transport Policy Institute [15], Department for Transport [8,65], May et al. [21] and Potter and Skinner [68].

peak-period traffi c by as much as 10–15%. One should be careful to understand the limitations of this technique though. Demand reduction efforts, unless under-taken on a truly massive scale, can have only a local impact in relieving spot con-gestion and subsequently they will not appreciably reduce traffi c on highways and major arterials. A major barrier to the success of demand management strategies is that they require an adjustment in the lifestyles of travellers and the requirements of employers [67]. In formulating integrated strategies it is imperative to undertake thorough public consultation when TDM measures are considered for implemen-tation given public opposition. Table 8 illustrates TDM measures typically consid-ered in congestion management.

7.4 Which measures are more appropriate for congestion management?

Because the context within which the measures are introduced differs from city to city or town to town, it is quite acceptable to hypothesise that solutions at one location are not straightforwardly transferable to another. This may be so, but within the cosmos of choices made across many countries and cities, all with dif-ferent circumstances, it is possible to perceive that a degree of similarity in either approach or mechanism to alleviate traffi c congestion might be possible. From an operational planning point of view, it is very likely that overlap in international practice will occur, even if to a very small extent. This statement then begs some justifi cations and the question: ‘Are there any policy measures that have a success-ful track record in reducing traffi c congestion?’



Table 8: Demand management measures.

TDM measures to infl uence car use

TDM measures to infl uence public transport use

Regulatory restrictions Fare levelsCar sharing Fare structures, such as fl at fares, zonal fares

and monthly passesParking charges High occupancy vehicle (HOV) lanes

Charges for ownership of private parking space

Integrated ticketing systems

Urban road charging, including area licensing and road pricing

Concessionary fares, which are lower for identifi ed groups of users such as elderly people or those with low income

Fuel taxes Changes in bus and rail frequencies

Vehicle ownership taxes Targeted assistance for specifi c income groups

Company car taxation General subsidies for specifi c income groups

Public car park management

Workplace parking charges TDM measures for cyclists and pedestrians

Commute trip reduction programs Cycle lane regulations

Car restriction zones Bicycle and public transport integration

Toll roads

TDM information provision TDM provision for freight

Conventional direction signing Lorry routes and lane bans

Variable message signs Lorry parking and loading restrictions

Real-time driver information systems and route guidance

Parking guidance and information systems

Public transport timetable information

Trip planning systems

Source: Meyer [67], Victoria Transport Policy Institute [15], Department for Transport [8,65], May et al. [21], Potter and Skinner [68], Bell [1], Seik [70], Goh [71] and Dahlgren [72].

Heyns [73] assessed a variety of LUM, TDM and TSM measures available to tackle traffi c congestion and concluded that internationally there are similarities in the use of those adopted. The study highlighted those shown in Table 9 as the mea-sures with the most successful track record in reducing traffi c congestion.

Table 9 shows that no one particular type of measure is favoured or indeed pro-vides superior results; managing traffi c congestion comprises a balanced package of measures.



8 An Incremental Approach to Addressing Congestion

As noted in Section 7, current transport plans and LUM for urban areas do not rely solely on any of the contrasting measures described earlier. Rather, they rely on strategy integration or packages of measures, formulated to the needs of the urban environments within which the urban area is located. For example, it can be expected that proposals for larger towns will differ from those for smaller ones, and that urban areas of the same size population that are located in developed and newly developing countries would place different emphasis on the mix of land-use policy, road and public transport infrastructure and congestion and travel demand management measures proposed.

Key to successfully introduce congestion management involves an incremen-tal approach that goes beyond simply identifying the right combination of mea-sures. The decision maker has to consider deploying supporting initiatives that build up and foster a positive accepting environment rendering the integrated strategy publicly acceptable and sustainable particularly if TDM measures are

Table 9: Measures with the most successful track record in reducing traffi c congestion.

LUM TSM TDM

High development density Ramp metering Regulatory restrictionsDevelopment and encouraging

use of public transport HOV facilities Urban road charging

Development mix Park and ride facilities Vehicle ownership taxes

Development conditions Street design Fuel taxes

Development of travel plans Effective and reliable public transport

Public car park management

‘Smart Growth’ strategies New roads or additional lanes

Workplace parking charges

Clustered land use Parking controls Car restriction zones

Car-free planning Urban traffi c control (UTC) systems

Variable message signs

Land taxation policy Intelligent transport systems (ITS)

Driver information systems

Traffi c calming or restraint measures

Access control or management

Multimodal transport interchanges

Reversible lanes

Source: Heyns [73].



included. Such an incremental approach requires the following ingredients and steps:

• Public acceptability through transparency, consultation and democratic choice,• A set of circumstances that warrant the introduction of TDM measures,• Provision of public transport,• A fuel levy to fund transport capital expenditure (CAPEX) and operational

expenditure (OPEX),• A pilot study,• A traffi c congestion management plan (TCMP).

8.1 Promoting public acceptability through transparency, consultation and democratic choice

The fi rst initiative is to plan, develop and implement a procedure that takes into account the diffi culties expressed. To this end, public and stakeholder acceptability is likely to be increased by implementing an initiative incorporating the following four steps:

• Step 1: Recognise and discuss the problem publicly and openly,• Step 2: Consult prior to implementation,• Step 3: Consider the role of direct democratic approval,• Step 4: Implement followed by assessment and evaluation.

8.2 Circumstances that warrant the introduction of TDM measures

Many countries are now considering the use of more radical measures (as compared with parking control and traffi c signal control) to constrain the use of the private car on congested roads. One of the more thoroughly examined measures is that of road pricing. With a road pricing system, the effi ciency of operation on a congested road or road network is improved by employing the user-pay principle to make the car driver think very carefully about whether or not to use the controlled road(s).

Despite road pricing being an attractive policy tool, most attempts around the world to introduce economic incentives of this type have failed, not due to techni-cal diffi culties, but rather because the public did not support it. Empirical evidence suggests that road pricing is usually the fi nal tool in the toolkit being reached for by the policy maker as it is an extremely controversial and blunt economic tool to manage traffi c congestion and change road-user behaviour. Only when the integra-tion of conventional TSM, LUM and ‘softer’ TDM measures have failed, one con-siders ‘hard’ TDM measures such as road pricing. And even then, when ‘hard’ TDM measures are included as part of an integrated strategy aimed at traffi c-con-gestion management, the strategy should satisfy a number of operational require-ments and certain circumstances should prevail before they are publicly palatable and more effective.

Eliasson [74], Hau [75] and Schwaab and Thielmann [76] recommend the requirements and circumstances set out in Table 10 that have to be achieved and



should be in place for the policy maker to implement ‘hard’ TDM measures more successfully.

8.3 Provision of public transport

If people are to be induced to give up driving into the city or town, they must have other means of getting there. Car sharing, switching to motor cycles, bicycles and walking will take care of some of the modal shift. In most circumstances, however, the main alternative is public transport, usually in the form of buses, bus rapid transit, trains and underground (metro) services. Most of these essential services are privately operated but are reliant and dependent on public funding or subsidisation. Prior to implementation of congestion management, the Transport

Table 10: Requirements and circumstances to make ‘hard’ TDM measures more successful.

From the road user’s point of view, it requires

From the road authority’s point of view

From the public/society’s point of view, it requires

User-friendliness and simplicity

The system goals have to be explicit and relevant

Fairness and the availability of alternatives

Transparency Get the legal conditions clear early on

Tolerance to a culture of non-compliance

Protection from invasion of privacy (anonymity)

Set out institutional requirements

Gradual introduction (a transitional phase or adjustment period)

Option for prepayment or post-payment

Determine funding, fi nancing and revenue allocation

Provision for mixed traffi c

Effi cient enforcement. Pass the revenue–cost test Passing the benefi t–cost test

Make provision for occasional visitors, be reliable, be secure and enforced,

Revenue recycling

Be fl exible to allow variable pricing

Minimum environmental intrusion

Enhance economic effi ciency

Provision for mixed traffi c

Ensure public transport effi ciency and reliability

Improved public transportation

Reduction in traffi c congestion

Limited or controlled traffi c displacement

Source: Eliasson [74], Hau [75] and Schwaab and Thielmann [76].



Authority has to initiate measures in terms of local integrated land-use and trans-port plans in order to ensure that public transport capacity has been suffi ciently increased to absorb the increased patronage (as a result of modal shift). If they do not do so, the public reaction could force the program to be abandoned in the face of stiff public opposition.

8.4 Apply a fuel levy to fund transport CAPEX and OPEX

An additional measure to fund the transport system might be to apply a fuel levy in the interim before full congestion management. Since fuel consumption is propor-tional to distance, given a certain engine class, a fuel tax is perhaps the best proxy for the amount of road usage. By uniformly taxing usage independent of time and place, the fuel tax is unable to differentiate between peak and off-peak periods and usage in congested and uncongested areas. The fuel levy will do nothing to reduce congestion, but it will generate signifi cant funding to support transport initiatives and the build up to full congestion management when a permanent package of measures is in place.

The disposition of the revenues collected from the fuel levy is crucial to its suc-cess and acceptability and should be explicitly explained to the public. Earmarking the proceeds would serve as an important prerequisite to the actual implementa-tion of marginal cost pricing in the road sector. Key areas of application of the proceeds should be funding and maintaining the transport system, road mainte-nance and improving and/or providing public transport.

8.5 A pilot study

For public acceptability and acceptance of the impact associated with congestion management, gradual introduction may be necessary at fi rst as examples from Singapore, the Netherlands, Norway and the United States show. A pilot study will help support the required change in driver behaviour. This stage also allows for fi ne tuning of the process and dealing with teething problems.

8.6 Introduce a traffic congestion management plan

As a possible fi nal step to managing traffi c congestion is the introduction of a Traf-fi c Congestion Management Plan (TCMP). A TCMP is envisaged as a systematic process with the principal goal of alleviating existing, or preventing future, traffi c congestion, thereby enhancing the mobility of persons and goods while encourag-ing sustainable development. Such a plan will ensure that an appropriate package of measures is implemented in the right place at the right time, with appropriate levels of public transport, funding, information provision and support, allowing much greater public acceptability. Tackling congestion requires a plan that encom-passes the complexities of the congestion problem and addresses the spatial extent of the urban environment’s travel patterns and the relevant institutional and pri-vate actors across the urban area. Figure 5 demonstrates a likely framework to the TCMP approach.



9 Conclusions

This chapter described why it is important to integrate transport planning and LUM specifi cally aimed at road-based, private car traffi c-congestion reduction in urban areas.

It considered the intrinsic relationship between transport and land use and why integration is important. It explained the inter-relationship between speed and fl ow with reference to the speed–fl ow theory. It then explained how we should plan for greater sustainability in land use and transport and identifi ed a menu of measures that should be adopted as part of the planning process. It also outlined the circum-stances that should prevail before traffi c congestion management is implemented before fi nally outlining a possible incremental strategy to addressing congestion in urban areas.

Developing integrated strategies aimed specifi cally at reducing road-based traf-fi c congestion is no longer an option in LUM and transport planning, but an essen-tial requirement if traffi c-congestion reduction and sustainable communities are to be left as the legacy of today’s planners. Policy makers must adopt a transport planning systems approach, which goes beyond implementing a single TDM measure or a few measures on a piecemeal basis. The key to managing traffi c

Figure 5: Components of a TCMP. Source: Heyns [73].



congestion is implementing a balanced package of measures that cut across sup-ply, demand and LUM measures as part of a systematic process.

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CHAPTER 5 Managing Traffic Congestion – The Case of · PDF fileCHAPTER 5 Managing Traffic Congestion – The Case of Land-Use Management and Transport Planning Integration Dr. Werner