Economic, Environmental and Social Impacts of Changes in Maintenance Spend on Local Roads in Scotland

7 Impacts from Carriageway Operations

7.1 Overview

Road carriageway pavement maintenance interventions on the road network require traffic management during the maintenance works. Traffic management causes delays to vehicles using the network with a corresponding economic cost to road users. The amount of delay is related to the traffic flow on the road, the works length, closure speed and the type of traffic management used.

Therefore, the amount and type of maintenance carried out on the network has an impact on the costs of delays to road users. More maintenance treatments require more lane closures and generate more traffic delays. The expectation is that as maintenance budgets are cut and the amount of scheduled works is reduced, the costs of delays to road users will decrease. The counterpoint to this is that increased deterioration of carriageway condition may lead to an increase in accidents (e.g. skidding related accidents). However for the purposes of this analysis these 'rebound' effects have been considered separately in Section 6.4.

7.2 Roadworks and user delay costs

To calculate the user delays caused by roadworks the QUADRO (Queues and Delays at Roadworks) model (Highways Agency, 2009b) was used. Traffic levels based on the network traffic data were used with the extent of maintenance works in each of the analysis years estimated from the outputs (treatment lengths) from the WDM analysis. The WDM model applied treatments based on the network condition and available budget. Details of the analysis methodology and results from all 8 sample Authorities is given in Appendix H. Results for Fife are shown in Figure 7.1.

Figure 7.1 User delay costs at roadworks - Fife
(2002 prices undiscounted)

The reduced funding in Scenarios 2 and 3 clearly show the effect of less maintenance work up to 2020. As the funding for the Scenarios increases, the delays to road users increase until, from 2025, there is little difference between the 'in-year' costs for the 3 Scenarios. The increase in traffic flow contributes to the overall gradual trend increase in delay cost for all 3 Scenarios (e.g. in Scenario 1 with constant maintenance funding, there is an increase in the costs of user delays through the analysis period).