MASTER - Final Summary Report
Project Coordinator: VTT Communities & Infrastructure (VTT, Finland)
University of Leeds - Institute for Transport Studies (ITS, U.K.)
KTI Institute for Transport Sciences Ltd (KTI, Hungary)
Lund University - Department of Traffic Planning and Engineering (LU, Sweden)
TNO Human Factors Research Institute (TNO, the Netherlands)
Transport Research Laboratory (TRL, U.K.)
University College London - Centre for Transport Studies (UCL, U.K.)
SWOV Institute for Road Safety Research (the Netherlands)
Swedish Road and Transport Research Institute (VTI, Sweden)
Project duration: 11.09.1996 - 10.09.1998
Date: January 1999
2. TECHNICAL DESCRIPTION
3. RESULTS AND CONCLUSIONS
3.2 Impacts of Speed
3.3 Framework for Assessing the Impacts of Speed
3.4 Drivers' Choice of Speed
3.5 Innovative Speed Management Tools
3.6 Current Knowledge of Speed Management Measures and Tools
3.7 Recommendations for Speed Management
5. EXPLOITATION AND DISSEMINATION PLANS
6. NAMES AND ADDRESSES OF THE COORDINATOR AND ALL PARTNERS INVOLVED
The objective was to produce information that can be cited in the preparation of national and EU decisions concerning speed management strategies and tools. For this purpose, the project looked for answers to three key questions:
The MASTER project aimed to develop recommendations for speed management strategies and tools. To achieve that the impacts of speed, the factors influencing drivers' choice of speed, and the existing and potentially available speed management tools were systematically and comprehensively described and assessed. The methods used in the different workpackages included literature reviews, questionnaire surveys, road-user interviews, development of accident prediction models, development of a framework for assessing the impacts of speed, simulator studies and field studies.
Speed management is seen as a process with two main phases. The first phase is the determination of desirable or target ranges of speed for each section of road. It is suggested that the target ranges of speed should reflect the socially desirable balance of all impacts of speed (e.g. travel time, accident risk, vehicle operating costs, environmental impacts and distribution of impacts between groups of people). The second phase is the application of various speed management measures and tools that best promote the adoption of target ranges of speed.
The responsibility for speed management is typically divided between several national and local authorities. The role of the EU is rather minimal. Speed management often lacks explicit goals and integrated long-term plan. Posted speed limits are the backbone of speed management in Europe. Speed is limited on all roads except for some sections of German motorways. There are great variations in speed limits on similar roads in Europe, especially on rural roads and motorways. Speed limits are typically set for safety reasons, and reflect road and traffic conditions. There is little evidence, however, that present speed limits are optimal from the viewpoint of society, the road transport system, or the individual road user.
Drivers frequently exceed the speed limit with up to 80 per cent speeding. This indicates that speed limits need to be supported by other measures to keep speeds at desired level. Speeding occurs especially on low speed urban roads and on motorways. Data from some countries indicate that driving speeds and speeding are systematically increasing.
Accidents: Studies summarising findings from before-and-after studies of the impacts of speed on accidents have resulted in a rule of thumb saying that a 1 km/h decrease in mean speed causes a 2 to 3 per cent reduction in injury accidents. Importantly, speed increases not only the number but also the severity of accidents. Work within MASTER on speed-accident relationships has demonstrated that cross-sectional log-linear statistical modelling offers the prospect of cross-national models that could estimate the effects speeds upon accidents on particular categories of road in Member States.
Environmental impacts: The major pollutants from road transport are oxides of nitrogen whose emissions increase with speed, hydrocarbons whose emissions generally decrease with speed, and carbon monoxide and particulate matter whose emission levels are lowest at medium speeds. Carbon dioxide emissions are proportional to the amount of fuel consumed. Acceleration can cause disproportionate emissions. At speeds above 40-50km/h noise from traffic increases linearly with speed. Acceleration and braking cause a small increase in noise.
Costs to users of vehicles: Speed affects travel time and vehicle operating costs. Some changes in costs in terms of time and money may be quite accurately perceived by the vehicle users; other changes may be appreciably misperceived. Changes in costs to users do not imply equal changes in cost as reckoned by governments from the point of view of society. Whereas monetary and other material costs mount up in value additively whether they are incurred in a few large increments or many smaller ones, it is strongly debated whether the same is true of changes in travel time.
Distributional impacts: Gains from changes in speed for one group of people often mean losses to some other group. This may raise concern about equity, the ethical desirability of the distribution of benefits and costs among groups and individuals, and to the corresponding injustice caused by substantial uncompensated losses. From society's point of view equity and distributional impacts can be equally important as the magnitude of total benefits and costs.
Network level impacts: If speed management changes the accessibilities of locations in relation to each other, spatial socio-economic effects may occur in the long run resulting in changes in traffic volumes and choices of travel mode. Studies on the impacts of changes in speed often consider only link level impacts, which usually means assuming that traffic volumes remain unaffected. Network level studies that take into account also the impacts on traffic volumes are more laborious and rare.
It is helpful for the decision-makers to be as fully informed as is practicable about the effects that any speed management policies and measures they are considering may have. This is helpful not only to their own decision-making, but also in their task of consulting the affected people. The MASTER framework for assessing the effects of traffic speed was developed and tested for these purposes.
The MASTER framework is a tool for systematic and comprehensive assessment of the impacts of (changes in) speed. The point of departure was social cost-benefit analysis including the assessment of both the magnitude and distribution of impacts. The main phases of the assessment process are:
1. description of the case to be assessed;
Drivers' choice of speed is affected by the driving speed of fellow road users and by how people evaluate the opinions and reactions of significant others (family, friends, passengers, the police and the government). People's intentions and behaviours are affected by the control people think they have over their behaviour. People also overestimate their own ability to control the consequences of speed.
Interviews of drivers and pedestrians in six countries indicate clear dissatisfaction with current levels of speed, in terms of the quality of urban life as well as road safety. There is a readiness at least in principle to see speeds reduced. This indicates that, notwithstanding current choices of speed by drivers, the climate for speed management policies for moderating speed may well be favourable.
Speed enforcement can significantly decrease speeds. Automated speed enforcement, e.g. by speed cameras, can be very cost-efficient provided that the driver does not necessarily have to be identified, but instead the owner of the vehicle can be held responsible. Speed reductions can be also achieved by road design measures. Physical measures typically force road users to reduce speed. A preferable solution would be "self-explaining" roads, so that drivers will be persuaded rather than forced to choose appropriate driving speeds.
To meet drivers' expectations consistently, a limited set of road categories that are easily distinguished from each other is needed, with appropriate speed levels dependent on the function of the road. The design elements of the road should consistently reflect the road category and thus support correct choice of speed. Results from simulator studies indicate that some design elements (e.g. lane width or presence of bicycle lanes) affect drivers' choice of speed more than other design elements and that providing redundant information about road category is not necessarily useful.
Speed management tools based on Advanced Transport Telematics (ATT) can informative (speed feedback) or intervening (in-vehicle speed limiters). In general, intervening systems are more effective in reducing speeds. Informative systems, on the other hand, appear to be more acceptable to drivers.
According to simulator studies the provision of speed advice to drivers results in reduced speed. As would be expected optimal performance is attained under an automatic system that regulates the maximum speed of the vehicle according to the prevailing road conditions. Dynamic speed control reduced significantly the mean speed and speed variance, as compared to advisory systems. The reduction in speed was especially high at village entries. However these benefits should be considered in the light of potential safety costs such as reduced following distances and possible complacency and loss of vigilance.
In the field studies of adaptive in-car speed limiter, the test drivers drove the same test route with the same car both with and without the speed limiter. Speed limiter reduced statistically significantly the mean driving speeds in urban areas. On most test sections the reduction was several kilometres per hour. On rural mixed traffic roads the effects on mean speed were smaller, possibly because of congested driving conditions on these test roads. On the motorway test sections had high volumes of traffic and the mean speed of traffic was 5 to 10 km/h below the speed limit. Consequently, speed limiter had little effect on mean speed on motorways. However, the speed limiter effectively eliminated momentary high speeds on all types of road. The results of the field tests are best generalised to high-volume roads where the drivers seldom can choose their speed freely without being obstructed by other vehicles.
The total of 25 different speed management measures and tools were systematically described and assessed in terms of impact on speeds, other significant impacts, cost-effectiveness, and other relevant information. The measures are categorised as informative and legal measures, measures related to road design and intervening measures, and interactions between measures are discussed.
The following recommendations were made for general development of speed management measures, tools and policy:
1. Speed limits on roads of similar classification in different European countries should be harmonised so that road users' expectations are consistent with respect to correct choice of speed irrespective of previous driving experiences in their home country. These speed limits should reflect the socially desirable speeds.
2. European guidelines are needed for application of speed management measures and tools on residential and main roads in urban areas and on rural mixed-traffic roads.
3. Preparations for the introduction of adaptive in-vehicle speed limiters that automatically adjust the maximum speed of the vehicle according to the prevailing speed limit should be started.
4. Road design should be developed in order better to support drivers' correct choice of speed, e.g. by further development and application of the self-explaining road concept.
5. Automated speed enforcement should be developed further and taken into wider use. To improve the cost-effectiveness of automated enforcement, legislative changes are needed in some countries so that the owner of the vehicle can be held responsible for speeding offences.
6. The difference between the effects of speed on social and private costs should be reduced. If the cost of increasing (or decreasing) driving speed as experienced by drivers would follow more closely the respective cost to the society, drivers would voluntarily choose speeds that are closer to socially optimal speeds.
7. Information and publicity campaigns regarding the impacts of speed are needed. Such information could increase the public acceptance of speed restrictions that are justified from society's viewpoint. Nevertheless, decision-makers will still need to recognise that popularity is not necessarily a good criterion for speed management policies.
8. Speed limits should be extended to cover all roads in Europe, and the highest possible speed of vehicles should be restricted to the highest speed limit on motorways.
In addition, recommendations for speed management measures and tools are proposed for four different road categories: urban residential streets, urban main roads, rural mixed traffic roads, and motorways. For each category its key features and present speeds are discussed and recommendations for short-term and long-term speed management are made.
MASTER partners currently seek opportunities for co-operation with EU, national and local authorities and other parties in the implementation of recommended speed management measures and policies, the development of speed management tools and further research on the subject. They will welcome approaches for such purposes.
It is expected that the European Commission, national authorities and local authorities take the initiative in the exploitation of the results.
All 12 MASTER Deliverables 14 Working Papers are public and can be downloaded from the internet address http://www.vtt.fi/yki/yki6.
Project MASTER was presented in 11 papers at the Road Safety in Europe Conference in Bergisch-Gladbach, Germany, 23 September 1998. The papers are included in the conference proceedings. Presentations of MASTER were given also at the European Transport Conference, in Loughborough, England, 14-18 September 1998 and at the Transportation Research Board 78th Annual Meeting in Washington, D.C., 11-14 January 1999 (Pre-print No. 990646). A Further presentation is planned for the Road and Transport Research Conference in Brussels, 7-9 June 1999.
|Last Updated: 01-09-1999|