Economic, Environmental and Social Impacts of Changes in Maintenance Spend on the Scottish Trunk Road Network

ISBN 978 1 908181 48 0

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Content

2 Existing knowledge of impacts (Literature Review)

3 Transport Scotland road network
3.1 Extent of network
3.2 Amount of travel
3.3 Accident trends
3.4 Budgets
3.5 Pavement condition trends
3.6 Maintenance Schemes

4 Predicted network conditions
4.1 Pavement analysis
4.1.1 Overview
4.1.2 Scenario 1: Maintain current spend
4.1.3 Scenario 2: 20% reduction in budget
4.1.4 Scenario 3: 40% reduction in budget
4.1.5 Issues from the pavement condition analyses
4.2 Structures maintenance

5 Methodology
5.1 Overview
5.2 Focus of the study
5.3 Analyses and results

6 Refining the scenarios: A subjective assessment
6.1 Overview
6.2 Assessment approach
6.3 Assessment results
6.4 Conclusions on subjective assessment
6.4.1 Scenario 2: 20% reduction - focus of impacts
6.4.2 Scenario 3: 40% reduction - focus of impacts

7 Impacts of pavement condition
7.1 Literature review
7.1.1 General impacts and vehicle operating costs
7.1.2 Travel time based on deteriorating road conditions
7.1.3 Road safety impact and accidents
7.2 Overview of analysis
7.3 Surface conditions and vehicle operating cost
7.3.1 Translating remaining life into 3m LPV
7.3.2 Total network travel by condition
7.3.3 HDM-4 analysis
7.3.4 Analysis results
7.4 Surface conditions and travel time cost
7.5 Skid resistance and accident costs
7.5.1 Methodology
7.5.2 Analysis results

8 Impacts of pavement operations
8.1 Overview
8.2 Pavement roadworks and travel delay costs
8.2.1 Scheme data
8.2.2 Treatment durations
8.2.3 Delay costs
8.3 Analysis results

9 Impacts of other maintenance operations
9.1 Overview
9.2 Major structures and impact on the road user
9.3 Winter maintenance and travel delay and accident costs
9.3.1 Literature review
9.3.2 Winter maintenance assessment
9.4 Lighting operations, travel time and accident costs
9.4.1 Literature review
9.4.2 Lighting the network
9.5 Analysis results

10 Impact on depreciation
10.1 Depreciation of vehicles
10.2 Depreciation of the road network

11 Impacts on customer satisfaction
11.1 Overview
11.2 Literature review
11.3 Customer satisfaction surveys and potential impacts

12 Impact on carbon footprint
12.1 Overview
12.2 Analysis results
12.2.1 Carbon emissions from maintenance works
12.2.2 Carbon costs from vehicle CO₂ emissions

13 Summary of changes and impacts
13.1 Results summary
13.2 Results discussion
13.3 Assumptions and sensitivity
13.3.1 Inflation on maintenance works costs

14 Conclusions and recommendations

References

Glossary

Acknowledgements

Appendix A Further Details of the Trunk Road Network

Appendix B Subjective assessment of maintenance spend

Appendix C Pavement Network Model outputs

Appendix D Summary of key data and assumptions

Appendix E Detailed annual and cumulative costs

Appendix F Increase in travel time costs

List of Figures

Figure 3.1 Numbers of accidents by lighting levels
Figure 3.2 Number of accidents by road surface condition
Figure 3.3 Number of skidding accidents by road surface condition
Figure 3.4 Skid resistance and road surfacing budgets
Figure 3.5 Pavement condition and maintenance budgets
Figure 3.6 Total length of schemes by road type and year
Figure 3.7 Total length of schemes by treatment type and year
Figure 3.8 Number of maintenance schemes by road type and year
Figure 3.9 Average scheme length by road type and financial year
Figure 4.1 Relationship between RCI and pavement remaining life
Figure 4.2 Scenario budgets
Figure 4.3 Network length by remaining life (0-40 years) - Starting Condition
Figure 4.4 Network length by remaining life for Scenario 1
Figure 4.5 Network length by remaining life for Scenario 2
Figure 4.6 Network length by remaining life for Scenario 3
Figure 7.1 Outline methodology for converting remaining life to 3m LPV
Figure 7.2 Assignment of traffic to network lengths by 3m LPV
Figure 7.3 Variation of vehicle operating costs with road roughness
Figure 7.4 Projected annual vehicle operating costs
Figure 7.5 Motorway annual vehicle operating costs
Figure 7.6 Dual APTR annual vehicle operating costs
Figure 7.7 Single APTR annual vehicle operating costs
Figure 7.8 Predicted travel time costs (Scenario 1)
Figure 7.9 Predicted travel time costs (Scenario 2)
Figure 7.10 Predicted travel time costs (Scenario 3)
Figure 8.1 Total annual delay cost for each Scenario
Figure 12.1 Costs of carbon from maintenance works
Figure 12.2 Carbon costs due to pavement condition for each Scenario
Figure B.1 Allocation of works to budget heads (1)
Figure B.2 Allocation of works to budget heads (2)