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SOUTH DUBLIN COUNTY COUNCIL

South Dublin County Council Crest

MEETING OF SOUTH DUBLIN COUNTY COUNCIL

Monday, April 08, 2024

QUESTION NO.10

QUESTION: Councillor M. Lynch

To ask the manager to comment on the viewpoint that the narrowing of roads and tightening of corners leads to greater wear and damage of roads as all tyres hit the same narrow stretch of road.

REPLY:

The Council does not believe that narrowing the carriageway width leads to greater wear of roads.

On all carriageways, irrespective of the design width, there is what is called a "wheel track" and oil track section of road.

The wheel track is the general location of the wheels of a vehicle on the road. In practice this usually means there is a consistent line where most tyres track down a typical carriageway.  This tyre line does get worn more than the track between the tyres (the oil track) because the tyres over time abrade the stone aggregate surfacing and polish and wear the stone texture.  Even on relatively wide carriageways drivers position their cars in the same position of the carriageway.  That is a set distance from the kerb line on the passenger side and set distance from the center line of the carriageway.

Meanwhile the oil tack, the space between the tyres, gets little abrasion and therefore does not damage as quickly as the tyre tracks.

In the narrowed traffic calmed carriageway scenario, there will still be a tyre track and an oil track.  There will still be the same number of vehicles travelling over these tyre tracks and the abrasive and polishing of the surface will be the roughly the same as in the wider road example.  Therefore, in a straight line of road the wear and damage rate is the same in both a wide road and narrowed road example.

In relation to the tightening of corners. The tighter turning of lorries in theory can lead to more abrasion of the road surface.  However, the less speed of the turning movements can reduce the abrasive forces applied to the road surface also.  So the negative effect is balanced by a positive effect.  Therefore I suggest the net effect is neutral.

In conclusion, it is believed that the narrowing of roads and the tightening of corners will have a negligible effect on the life expectancy of the typical road surface.