Black Isle and Lochaber to trial new roadside ditch maintenance regime
Black Isle and Lochaber have been chosen as areas for a trial project which will identify priorities for maintaining roadside ditches, thereby protecting road surfaces and removing the need for costly repairs.
If the trial proves successful, it will be rolled out throughout the Highlands from March next year.
The Council is following a methodology for prioritising open ditch drainage maintenance established through a collaborative project, called Roadex, involving road authorities from the northern European countries in Scandinavia and Iceland.
The first step is to carry out a survey of roadside ditches using cameras mounted on the roof of a vehicle which are linked to GPS software. The video output is analysed and the drainage categorised as good, adequate or in need of improvement by comparison with recommended standards.
A map is produced identifying the areas in need of maintenance which can then be analysed in more detail by technical staff to determine the most appropriate treatment, from simple cleaning to verge height reduction, edge stabilisation or creation of a new drainage system.
The timetable for completing and assessing the outputs from the trials is:
• June 2013 - Procure survey equipment (vehicle mounted cameras linked to GPS software)
• July 2013 - Carry out survey of roadside ditches in trial areas
• August to September 2013 - Analyse output from survey
• October 2013 - Develop prioritised programme of roadside ditch maintenance for the trial areas
• November 2013 to February 2014 - Complete prioritised maintenance programme
• March 2014 - Evaluate trial and develop options for a wider roll-out
The Programme for the Highland Council includes a commitment that the Council will instigate a co-ordinated, thorough, Highland-wide programme of inspecting watercourses and cleaning gullies and ditches to avoid further water damage. The maintenance of roadside ditches and off-lets (channels cut into verges) helps to ensure that water can flow freely from the road surface into the roadside ditch, thus keeping the road surface free from water.
Properly maintained roadside ditches also helps to lower the ground water table and prevents the road sub-grade from becoming saturated and losing strength. Loss of strength in the road sub-grade leads to deformation and cracking in the road surface.
Councillor Graham Phillips, Chairman of the Council’s TEC Services Committee said: “The ROADEX project demonstrated that surface water can, in some areas, cause more damage to a road than traffic. Money spent on roadside drainage will prolong the life of the road and fits well with the Council’s commitment for preventative spend. The ROADEX methodology provides a means of targeting our resources at the areas of greatest need.”
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