TWO zones in the Highlands have been selected for a trial project that could eliminate expensive road repairs.
The scheme will identify priorities for maintaining roadside ditches, resulting in better protection for road surfaces, and if the trials at Black Isle and Lochaber are successful the technique will be rolled out across the Highlands next year.
The local authority is following a methodology for prioritising open ditch drainage maintenance established under a collaborative project involving road chiefs from Scandinavia and Iceland.
The first step is to survey roadside ditches using vehicle-mounted cameras 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 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 – the 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, which can lead to deformation and cracking of the road surface.
Councillor Graham Phillips, who chairs the Council’s TEC services committee said: “Money spent on roadside drainage will prolong the life of the road and fits well with the council’s commitment for preventative spend.”
The timetable
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
