Economic, Environmental and Social Impacts of Changes in Maintenance Spend on the Scottish Trunk Road Network
2 Existing knowledge of impacts (Literature Review)
The challenge of identifying the economic impacts of maintenance investment is not new and Road Administrations around the world have sought to understand and justify their road maintenance programmes in terms of total transport cost for many years. However, until recently it has taken a secondary focus in most road economic research to the understanding of the economics of the initial road transport choice (e.g. the choice between route X or route Y) to ensure appropriate capital investment. There has been increasing work in this area in recent years as greater focus is applied to the efficacy of maintenance and operational investment.
The impact on a Road Administration of changes in road maintenance is the change in both operational and renewal budgets and also the overall capital asset value. The latter is based on the depreciation of the asset as it deteriorates and is often (e.g. by Transport Scotland) related to the asset condition through the use of road condition information (for the valuation model at Transport Scotland, this is the remaining life from pavement strength data).
The impact on the road user of changes in road maintenance falls into two broad areas. The first is the consequence of carrying out roadworks and operations, which affects the travelling public in terms of changes in travel time (e.g. queuing at roadworks or due to reduced winter service), accident rates (e.g. accidents at roadworks) and vehicle operating costs (e.g. fuel consumption). The second area of impact is the consequential change in road conditions (e.g. skid resistance and ride quality) which has follow-on effects on vehicle operating costs and other road user effects (e.g. road accidents) in the longer term.
Where available, at the start of each aspect of the analysis in this study, the report includes a brief overview of the latest research in the relevant topic area before a more detailed explanation of the analysis for this study.
Table 2.1 summarises the relative availability of literature on the various impacts of road maintenance, primarily those associated with the quantitative analysis. A fuller literature review of the wider impacts of changes in maintenance funding has been undertaken as part of the review of the impacts from the study for local roads given by (Transport Scotland, 2012).
Notes 1. Based on the literature review and knowledge of research on the topic.
2. H - Relevant literature available. M - Some literature but not widely reported or very locally specific. L - Limited literature for use in this study.