OTHER RECOMMENDATIONS — SHORT-TERM ISSUES
OTHER RECOMMENDATIONS — SHORT-TERM ISSUES
There were 10 recommendations which related to issues to be addressed in the short-term. Nine of these issues related to temperature, rain, wind and coastal flooding and the tenth was a general issue related to climate change predictions as a whole.
Design Issues
Recommendations 7 and 8 were identified to address the concern that the increase in temperature, combined with the increase in rainfall, suggested by climate change predictions could result in changes to the basic design assumptions underlying particular design elements.
- Recommendation 7: Review local experience on the durability of surface dressings and consider whether these or another intervention measure is appropriate for the location concerned.
Action: Scottish input has been made to the latest (6th) edition of Road Note 39 (RN39). This input reflects ongoing Scottish requirements in terms of suitably designed surface dressings. All surfacing requirements for the Scottish trunk road network are assessed on a scheme specific basis.
Status: Complete
- Recommendation 8: Consider the implications of an extended growing season when developing landscape designs, and specify slow-growing species where appropriate.
Action: The next revision of Cost Effective Landscape: Learning From Nature, is in preparation and is expected to be available for inclusion in the term maintenance contracts when these are next tendered. This revision will include consideration of the implications of climate change for landscape designs.
Status: Progressing
Case Study: Cost Effective Landscape
Cost Effective Landscape: Learning From Nature was first published by the Scottish Office in 1998 following an extensive consultation process. It provides policy guidance on landscape design, monitoring and management, supported by illustrative examples. It is currently under review to take account of policy and practice developments.
Design Issues
Recommendations 9 and 10 were identified to address the concern that the increase in rainfall suggested by climate change predictions could result in increased runoff which should influence the design decision on specifying particular drainage systems and/or introducing drainage systems into the road network where these have not previously been in place.
- Recommendation 9: Design drainage systems with additional storage capacity, taking account of sustainable drainage techniques, where appropriate.
Action: Transport Scotland considers that current design guidance encourages the adoption of such systems.
Status: Complete
Case Study: A9 WS2+1 Widening Schemes (Perth to Inverness)
The A9 between Perth and Inverness typically has an edge detail comprising kerbs, gullies and pipes. This detail provides a minimum hydraulic capacity and does not allow for the removal of any contaminants from surface water runoff prior to any outfall treatment. The edge detail adopted for the A9 WS2+1widening schemes2 was ‘over-the-edge’ drainage into filter drains. This detail provides additional storage in the filter trench during significant storm events and the filtration process allows the removal of some contaminants from surface water runoff.
- Recommendation 10: Introduce surface/sub-surface drainage during maintenance works where these do not exist at present, while recognising that this may not always be possible due to land-take constraints.
Action: Transport Scotland considers that current practice encourages the provision of drainage systems as part of maintenance schemes, where these are feasible and provide value for money.
Status: Complete
Case Study: A95 Kinermony Bends, Moray
When the A95 at Kinermony Bends was identified as requiring full reconstruction as part of the annual structural maintenance programme, the opportunity was taken to improve the drainage to comply with current design standards and good practice. This included a new ‘over-the-edge’ drainage system together with a supporting network of pipes and ditches.
Operational Issues
Recommendation 11 was identified to address the concern that the increase in rainfall suggested by climate change predictions could result in increased runoff events with the potential to cause scour at watercourse structures.
- Recommendation 11: Clarify the investigation requirements for watercourse structures potentially susceptible to scour, in terms of periodic and post-event inspection requirements.
Action: The current term management and maintenance contracts for the Scottish trunk road network include specific requirements in respect of scour inspections which address this issue.
Status: Complete
Design Issues
Recommendation 12 was identified to address the concern that the increase in wind suggested by climate change predictions could result in increased disruption to road users at exposed locations that might not be adequately assessed where use is made of historical wind data.
- Recommendation 12: When developing new designs, consider whether these will be susceptible to full or partial closure in high winds and prepare a cost/benefit analysis to assess the opportunity for including wind barriers at these locations.
Action: Transport Scotland is implementing this recommendation on individual projects as appropriate. A standard methodology for this process will be developed following completion of the High Winds Strategy (see Recommendation 13).
Status: Progressing
Operational Issues
Recommendation 13 was identified to address the concern that the increase in wind suggested by climate change predictions could result in increased disruption to road users at exposed locations.
- Recommendation 13: Continue the process of developing a High Winds Strategy for the trunk road network and consider the need for a similar approach on exposed sections of the local road network.
Action: The High Winds Strategy is at its final review stage and publication is due after agreeing the wind management procedures for trunk road network bridges with the Association of Chief Police Officers in Scotland (ACPOS) and the local police forces. This agreement is due to be in place by Winter 2008 and the estimated publishing date is March 2009.
Status: Progressing
Case Study: Skye Bridge, management of high winds
Transport Scotland has developed a set of procedures to manage the impact of high winds on a number of sections of the trunk road network. For the Skye Bridge, Transport Scotland works in partnership with the local police force, the local operating company and Traffic Scotland to monitor, control and inform the travelling public as to the conditions and/or restrictions in place. There are three stages of restrictions which are invoked when the agreed wind speed threshold for each stage has been breached. These stages are: Caution High Winds; Closed to High-Sided Vehicles; and Closed to All Traffic. Once a decision has been taken, information is displayed on Variable Message Signs on the trunk road network and also on the Traffic Scotland website: www.trafficscotland.org
Research Issues
Recommendation 14 was identified to address the concern that the current climate change predictions for wind have a high degree of uncertainty.
- Recommendation 14: Undertake further research on likely changes in wind patterns, including seeking to reduce the significant uncertainty that exists in regard to this issue. This would enable further guidance to be given on future consideration of wind in the design and operation of the road network.
Action: No action is being taken on this recommendation at present, pending issue of the next UKCIP datasets. These are now intended to be published in November 2008 following publication of an initial UKCIP report in December 2007, which described The climate of the United Kingdom and recent trends.
Status: Pending
Design Issues
Recommendation 15 was identified to address the concern that coastal flooding could be exacerbated by a combination of climate change predictions for various weather types that might not be adequately assessed where use is made of historical weather data.
- Recommendation 15: When developing new designs, consider whether these will be susceptible to coastal flooding, taking account of predicted sea-level changes and the possible effects of storm surges, and consider how the design should take account of any such susceptibility.
Action: Transport Scotland implements this recommendation on individual projects as appropriate.
Status: Complete
Research Issues
Recommendation 16 was identified to address the concern that the recommendations were made based on the then current climate change predictions and may be subject to change based on the outcomes of ongoing research in this field.
- Recommendation 16: Update this report as necessary following publication of the UKCIP06 report (now UKCIP08).
Action: No action is being taken on this recommendation at present, pending issue of the next UKCIP datasets. These are now intended to be published in November 2008 following publication of an initial UKCIP report in December 2007, which described The climate of the United Kingdom and recent trends.
Status: Pending