Transport strategy
Policy Instruments

The range of transport policy instruments
The detailed list of instruments
Bases for assessing performance
Sources of evidence
Summary assessment
Priorities and preferences
Types of integration
Potential Benefits from Integration

The range of transport policy instruments

Transport planners have available to them, at least in principle, a wide range of transport policy instruments. These are the means by which the policy objectives can be achieved and the problems identified overcome. They are the key elements of the strategy.

These instruments can be categorised in several ways. The approach which has been adopted in Konsult has been to group them under the following six headings:

  • land use measures
  • attitudinal and behavioural measures
  • infrastructure provision
  • management of the infrastructure
  • information provision
  • pricing

This grouping focuses on the type of intervention rather than the mode of transport, since the same principles often apply whichever mode is used. However, Konsult also distinguishes, for the final four categories, between measures which:

  • influence car use;
  • influence public transport use;
  • provide for cyclists and pedestrians;
  • provide for freight.

The detailed list of instruments

Land use measures

This set of measures focuses not on the transport system, but on the land use patterns which generate the demand for transport. The overall emphasis is to identify ways in which the demand for travel can be reduced, or modified to lessen its impact. The key measures identified are:

  • Development densities, involving an increase in density of development throughout an area to reduce the need to travel;
  • Development pattern, 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;
  • Parking standards for new development;
  • Commuted payments, whereby developers can provide less parking, but pay for public space;
  • Developer contributions to the financing of infrastructure;
  • Value capture taxes, designed to reflect the windfall benefits to existing developments from improved accessibility; and
  • Other land-use taxes, including property taxes.

Attitudinal and behavioural measures

These are measures which aim to change users' understanding of transport problems, or provide alternatives outside the transport sector, and hence induce changes in travel patterns. The principal ones are:

  • Indivdualised marketing campaigns, designed to encourage individuals to use alternatives which reduce overall travel, and travel by car;
  • Flexible working hours;
  • Telecommunications as an alternative to travel; and
  • Company travel plans, in which firms set out ways in which they can reduce their demands on the transport system.

Infrastructure measures

The measures listed under this heading involve additions or enhancements to the existing transport infrastructure. The main ones are:

Measures to influence car use

  • New road construction; and
  • New off-street parking.

Measures to influence public transport use

  • New rail stations;
  • New rail lines;
  • New rail services on existing lines;
  • Light rail systems;
  • Guided bus systems;
  • Park and ride;
  • Terminals and interchanges

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Provision for cyclists and pedestrians

  • Cycle routes;
  • Pedestrian routes; and
  • Pedestrian areas.

Provision for freight

  • Lorry parks; and
  • Transhipment facilities.

Management measures

The measures listed under this heading involve changing the way in which the existing transport infrastructure is used. They involve a wide range of approaches, including increases and reductions in road capacity, reallocations of that capacity, and changes in the operation of public transport. They include:

Measures to influence car use

  • Road maintenance;
  • Conventional traffic management;
  • Urban traffic control systems;
  • Intelligent transport systems, which use new technology to improve the performance of the road network;
  • Accident remedial measures, including speeds control;
  • Traffic calming measures;
  • Physical restrictions;
  • Regulatory restrictions;
  • Parking controls, including controls on duration, entry times and designated users
  • Car/Ride sharing and car clubs.

Measures to influence public transport use

  • Maintenance of existing fixed infrastructure;
  • New and modified bus services;
  • Bus priorities;
  • High occupancy vehicle lanes;
  • Changes in bus and rail frequencies;
  • Bus service management measures designed to improve reliability

Provision for cyclists and pedestrians

  • Cycle lanes and priorities;
  • Cycle parking provision;
  • Pedestrian crossing facilities; and
  • Safe routes to school, including innovations such as "walking bus services" in which children walk together.

Provision for freight

  • Lorry routes and bans; and
  • Lorry parking and loading restrictions.

Information provision

The measures listed under this heading involve improvements in the information available to transport users and operators. Some are traditional fixed information systems, others draw on real time applications of information technology. They include:

Measures to influence car use

  • Conventional direction signing;
  • Variable message signs;
  • Real-time driver information systems and route guidance; and
  • Parking guidance and information systems.

Measures to influence public transport use

  • Conventional timetable and other service information;
  • Real time passenger information;
  • Trip planning systems which provide information on alternatives before the start of the journey
  • Operation information systems such as bus fleet management.

Provisions for cyclists and pedestrians

  • Static direction signs; and
  • Tactile footways.

Provision for freight

  • Static direction signs; and
  • Fleet management systems.

Pricing measures

The measures listed here involve changes in the cost of transport use for both private vehicles and public transport. They include:

Measures to influence car use

  • Parking charges;
  • Charges for ownership of private parking space;
  • Urban road charging, including area licensing and road pricing;
  • Vehicle ownership taxes; and
  • Fuel taxes.

Measures to influence public transport use

  • Fare levels;
  • Fares structures, such as flat fares, zonal fares and monthly passes;
  • Concessionary fares, which are lower for identified groups of users such as elderly people.

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Bases for assessing performance

All of the above policy instruments will affect the performance of the transport system in one or more of three ways:

  • by changing the demand for travel
  • by changing the supply of transport facilities
  • by changing the cost of provision and operation of the transport system.

It is through these three types of change that the instrument can help to achieve policy objectives and overcome transport problems; conversely these changes can, if inadequately understood, lead to new problems, and failure to achieve certain objectives.

Changes in demand

When faced with a new policy instrument, or with a change in an existing one, such as a fare increase, the individual traveller has a number of options; the principal ones are:

  • continue as before
  • change the number of journeys made
  • combine journeys ("trip chaining")
  • change destination
  • change departure time
  • change mode (including mixed modes such as car sharing and park and ride)
  • change route.

Some of these changes may be made immediately, while others may take longer, particularly if other activities have to be adjusted. For example, a change in destination for shopping journeys can be immediate, while one for work will depend on being able to change job. In addition there are two further responses which are almost certainly longer term ones:

  • change ownership of vehicles (cars, motorcycles and cycles)
  • change home.

In Level 2 the assessment considers in turn each of these types of potential change, and assesses for each whether they are likely to be short, medium and/or long term, and how strong the response is likely to be on a 0-3 scale. Similarly the case study results present evidence on this basis.

The scale of response will depend very much on the circumstances. Those who are directly exposed to a change are likely to respond more strongly than those for whom information on the change is indirect. Thus car users are less likely than bus users to respond to a reduction in bus fares, while the reverse is true for fuel prices. Those for whom the journey, by the current means, is particularly important may well be more reluctant to change, unless the alternative offers a considerable improvement. Those who have few or no alternatives are obviously less likely to change. Longer term changes, and those with longer term implications, are likely to be dependent on perceptions of the consistency and continuity of the strategy. For each of the types of change, Level 2 considers the circumstances in which change is more likely to occur.

The level of change in demand can be determined by knowledge of the change in the policy instrument in question and of the relevant elasticity of demand. Demand elasticities are generally calculated by estimating the proportionate change in demand for a good or service resulting from a one percent change in a measure of the supply of that good or service. Demand can be measured in trips or in trip-km for a given mode in a given circumstance. Supply can be defined in a number of different ways, including price, travel time, frequency or overall ("generalised") travel cost and it is important, in interpreting elasticities, to know which definition is being used. In particular, price might relate to "generalised cost", whereby all monetary and time-related costs to the user are bundled together, assigning a value to the time elements, or it might be defined in relation to one particular component of cost, eg fuel price or parking cost. Elasticities can also be measured for demand for the mode being affected (for example bus trips in response to changes in bus fares) or for demand for a competing mode (for example car trips in response to bus fares). The latter is referred to as a cross-elasticity.

Changes in supply

Changes in the supply of transport can take a number of forms, some of which will have a direct influence on travellers, while others will only impact on them if they are perceived. The principal ones are:

  • changes in the capacity of the road or public transport network
  • changes in the allocation of road capacity through, for example, priority lanes
  • changes in permitted speeds, through speed limits or physical measures
  • changes in the access cost or time to public transport through, for example, changes in routes, frequencies, reliability or provision of park and ride
  • changes in the costs of use, through changes in fares charges or fuel prices
  • changes in the information available, either as static, variable or real time information.

For most policy instruments, the ways in which they affect supply are self-evident, but the scale of effect is not always clear. In Level 2, information is given for each policy instrument on the nature and level of the changes which are likely to arise.

Interaction of demand and supply

The effects of demand and supply changes can best be interpreted by an understanding of the shape of demand and supply curves. A demand curve (see below) represents the way in which demand (in say trips) on the x-axis changes as costs (on the y-axis) rise or fall. A supply curve shows how costs of use, on the y-axis, rise as the level of use, on the x-axis, rises. That shown is a typical supply curve in a road network, in which average costs rise slowly at first, as increased traffic results in reductions in speed, and then rise much more rapidly as capacity is reached and delays occur. A public transport supply curve would reflect, instead, the extra costs of having to wait for the next bus as bus capacity is reached. The intersection of the demand and supply curve determines both the number of users (X in the figure below) and the cost per user (Y in the figure). These in turn can be used to determine the impact on both policy objectives and problems.

Interaction of demand and supply

The way in which a policy instrument affects demand and supply curves will vary, as illustrated in the figures below, which represent five different types of change in the demand and supply for car use. In the first figure, the capacity of the road system has been increased, for example through traffic management; the supply curve has changed, but the demand curve, at least in the short term, has not, since the same number of users would wish to travel at a given cost. As a result, the number of users has increased, and the average cost of use has fallen. In the second figure, the capacity has been reduced, perhaps through a road closure; again the supply curve has changed, but the demand curve has not; the number of users has fallen, and the average cost increased. In the third figure, the demand for car use has fallen, perhaps through a reduction in public transport fares or a successful awareness campaign; the demand curve has changed, but the supply curve has not, since the costs of use at a given flow remain the same. As a result, the number travelling has fallen, as has the average cost of travel. In the fourth figure, the demand for car use has risen, perhaps through a deterioration in public transport services or an improvement in driver information. Again, the demand curve has changed but the supply curve has not; the number of car users has increased, as has the average cost of travel (though in this case, improved information may have reduced the perceived cost of use). In the fifth figure one of the many possible combinations of the above effects is shown. In this case, demand for car use has fallen, as has the capacity for car use. This could result, for example, from reallocation of road space to light rail. As a result both the demand and supply curves have changed. The number of car users has fallen, but the effect on average cost will depend on the relative changes in the demand and supply curves.

Changes in demand and supply for car use

Changes in costs
By comparison, the effects on costs are more easily assessed. However, it is important that they are not overlooked. For example, the first figure above suggests that traffic management can provide benefits both for current users through reduced costs and for new users who are enabled to travel. However, it is perfectly possible for these benefits to be outweighed by the costs of implementation or enforcement.

The principal types of cost change are:

  • changes in capital costs, usually through the costs of new measures
  • changes in the cost of vehicle operation for users, which are included in the supply costs above
  • changes in the operation costs for suppliers, including enforcement, administration, and public transport vehicle and driver costs
  • changes in the cost of maintaining and replacing the transport infrastructure and services.

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Sources of evidence

In an ideal world each significant policy instrument introduced would be assessed, through a before and after study, to determine whether it had performed as expected. In this way we would be able, as a profession, to build up a record of experience of each policy measure, in the range of contexts in which it had been applied, and thus enhance both our capabilities in policy formulation and the models which support it. Unfortunately, in practice, opportunities are seldom taken to carry out such appraisals. To take a simple example, the UK has had a programme of major road construction for the last 40 years. Yet when the M25 orbital motorway around London was completed in the mid 1980s, and rapidly became congested, there were no past detailed before and after studies to explain what had gone wrong. Instead it took some ten years of debate before it was accepted that providing new road capacity could, in certain circumstances, increase demand and thus provide far less congestion relief than had been predicted.

There are some policy instruments, including bus priorities, light rail provision and, more recently, Intelligent Transport Systems, for which demonstration projects have been implemented and documented. These are the best sources, since they usually indicate the performance of an instrument in a range of situations. There are others where individual studies have been conducted and reported in the professional literature. Some of these are of doubtful value because they have not been subject to a professional audit and may, in the extreme, have been designed to justify a scheme which was in practice less successful. There are, no doubt, far more which have been assessed, but where those carrying out the assessment have not seen fit to publish their results.

In addition to the limited before and after studies, some evidence is available from desk studies which have used computer models to predict the impact of a policy instrument. This is, for example, still the main source of information on road pricing and comprehensive parking controls. These are potentially valuable but, of course, critically dependent on the quality of the model used.

There have been a few attempts in the recent past to draw together this information; in some cases for a group of policy instruments (Webster et al 1980; ERTICO, 1998; Westerman, 1999); in others for the full range of policy measures (IHT, 1996; May and Still, 2000). What follows is based on the last of these. One of the most interesting attempts is the first web-based version: the "Transport Demand Management Encyclopedia," which was launched in 2000 (

One of the greatest problems in developing an information source of this kind is to know whether results can be transferred from one location to another. If a measure performs well in one city but not in another, is it because it has been implemented more effectively in the first? Or are the institutional arrangements different? Or is it because the cities are subtly different in their topography, density or demography? Or are there differences in culture which affect the willingness of individuals to obey regulations or to switch modes? All of these factors make it very difficult to transfer results from one city to another, even in the same country, let alone between continents or cultures.

Summary assessment

The coverage of each policy instrument in Level 2 is structured into five sections:

1. a description of the policy instrument and the way in which it operates, with more detail provided for those which are less well known of more complex;

2. a first principles assessment, which assesses in turn the expected impacts on demand, supply and costs; considers the resulting implications for objectives and problems, both assessed on a -5 to +5 scale, with brief explanatory text; identifies the main winners and losers, again assessed on a -5 to +5 scale; and finally considers the severity of the main barriers to implementation, on a 0-5 scale, drawing on the general consideration of barriers in Section 6 below;

3. presentation of the evidence from both case studies and desk studies, following a similar structure to that of the first principles assessment;

4. a summary assessment, which considers again the performance against objectives and problems, based on the evidence available (again on a -5 to +5 scale); assesses the likely contribution of the instrument in a number of contexts ranging from city centres, to higher and lower density suburbs, to smaller towns, again on a 0-5 scale; and briefly discusses potential side effects; and

5. identification of the complementary measures which are most capable of overcoming adverse side effects and reinforcing the performance of the instrument, as a link both to the coverage of these complementary instruments.

The tables which appear throughout Level Two are experimental. We would very much welcome feedback on the usefulness of their content and design.

Priorities and preferences

European cities were asked for their assessment of the importance of 10 policy measures from these lists, chosen to reflect the range of types of instrument. The results are shown in the figure below. Over 80% identified bus priorities and bus and rail frequencies as important or very important, and for most of the remainder at least 60% did. However, only 30% considered road pricing important, and only 20% flexible working hours. Smaller cities placed less emphasis on awareness campaigns, rail provision, bus priorities and real time information than did medium and larger cities. Medium cities placed greater emphasis on parking charges but less on road pricing. Larger cities were less concerned with development patterns and with fares. In addition, the survey cities identified a number of other policy measures which they believed to be important, including park and ride, supplementary housing construction, mobility management and pedestrianisation.

Importance of different measures in 54 survey cities

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Types of integration

No one instrument on its own is likely to provide a solution to transport problems. Most have at least one positive contribution to make, in reducing travel time, environmental impact or accidents, but also have adverse impacts on, say, accessibility or equity. Some, such as traffic calming, can achieve benefits in one area at the expense of deterioration elsewhere. Some, such as bus priorities, would be more effective if they could influence mode choice; without such an impact they only benefit the users of the affected mode.

For all of these reasons, a package of measures is likely to be more effective than selecting any one measure on its own. A set of measures is likely to tackle more problems; one measure can offset the disadvantages of another or avoid the transfer of problems to another area; a second measure can reinforce the impact of the first, for example, inducing a change of mode and generating greater benefits.

In these ways, synergy can be achieved between measures; that is, the overall benefits are greater than the sum of the parts. The identification of measures which might achieve such synergy is at the core of successful transport planning.

There is currently considerable discussion of the principles of integration. However, much of this focuses on integration specifically within public transport. There is, in practice, a third and more strategic form of integration which is directly relevant to strategy formulation: the integration of policy measures to achieve greater performance from the overall strategy. Such integration can occur in four broad ways:- integration between authorities within a conurbation; integration between measures involving different modes; integration between measures involving infrastructure provision, management, information and pricing; and integration between transport measures and land use planning measures.

Potential Benefits from Integration

Integration at the strategic level can potentially achieve benefits in several ways. The first involves measures which complement one another in their impact on users. Obvious examples are the provision of park and ride to increase rail or bus patronage; the use of traffic calming to reinforce the benefits of building a bypass; the provision of public transport, or a fares reduction, to intensify the impact of traffic restraint; and the encouragement of new developments in conjunction with rail investment.

The second involves measures which make other elements of the strategy financially feasible. Parking charges, a fares increase or road pricing revenue may all be seen as ways of providing finance for new infrastructure.

The third concerns public acceptability, and the need to package measures which are less palatable on their own with ones which demonstrate a clear benefit to those affected. Once again an example is to be found in road pricing, which attitudinal research demonstrates is likely to be much more acceptable if the revenue is used to invest in public transport.

The diagram below shows a selection of those measures described in previous sections, those which are particularly likely to complement one another in one of these ways. This diagram is intended to be used as a broad design guide only, not as a definitive assessment of instrument capability (IHT, 1996).

There are important messages here, not just for the development of an integrated strategy, but for the sequence in which measures are to be implemented. Clearly those which need to be implemented to facilitate others are required first. It will also be essential at least to be committed to those measures which generate income before investing in those measures which depend on that revenue for finance. Similar considerations arise with measures which influence public acceptability: commitments are needed to publicly attractive measures before embarking on those which on their own are less attractive. Here, however, there is the continuing risk that the less attractive measures will still not be implemented, for fear of public criticism. It is preferable if both positive and negative measures are implemented together.

Use the blue arrows to select a measure.

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Text edited at the Institute for Transport Studies, University of Leeds, Leeds LS2 9JT