Driving speeds significantly affect practically all key attributes of road transport. Therefore, in pursuit of a more efficient, safe and environmentally acceptable road transport system, we must be able to assess and predict the various effects of changes in driving speeds. This report describes a systematic and comprehensive framework for such assessment. The MASTER framework enables the assessment of impacts on a) vehicle operation costs, b) travel time, c) accidents, d) pollution, and e) other potential impacts regarded relevant. The effects of speed on both the magnitude and the distribution of these impacts are considered. In addition to the direct effects, the framework is suitable for estimating indirect or network-level impacts, e.g. the effects of changes in perceived accessibility and traffic behaviour caused by changes in speed. The magnitudinal effects are described on three levels: monetary, other quantitative, and qualitative effects. The framework resembles cost-benefit analysis (CBA) in the sense that many of the impacts are usually expressed in financial terms. Monetised impacts are also described in their original units (e.g. accident costs as well as numbers of accidents). Impacts that cannot easily be transformed into monetary amounts are described quantitatively where possible (e.g. amount of C02 emissions in tonnes if a proper monetary value is not available). In cases where quantitative assessment is for some reason not possible, the impacts are described qualitatively (verbally). Distributional effects are assessed by mapping the positive and negative impacts on the various groups on an ordinal scale. The framework guides the analysis of impacts and the presentation of results. However, users applying the framework are free to choose the impact functions, e.g. how accidents or exhaust emissions depend on speed. The minimum data needed for application of the framework consists of the length of the road section or network under consideration, information on traffic volumes, the mean speed of traffic before and after the speed change and the expected number of injury accidents before the speed change. In practice, a considerable amount of additional data is often needed depending on the functions and models used for the prediction of different impacts. Data needs and application of impact functions are illustrated in an example. If the task is to manage speeds on a road network instead of just one section of a road, a network model is needed, preferably one that features land-use transport interaction in order to account for the full range of effects caused by changes in accessibility. In comparison to previous approaches to the estimation of the overall effects of speed, the MASTER framework concentrates on ease of application and description of the assessment framework rather than presentation of results from application. The framework is flexible. It allows the user to employ simple or sophisticated impact functions or models according to the situation. The user can also choose the unit prices of the various effects. Other features of the framework are its transparency, and systematic and clear presentation of results. The various effects of speed are described plainly, but with an emphasis on avoiding unwarranted simplification. (A)
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