A dual carriageway is not justified by the traffic volumes. Statistics for the
NRA Woodruff traffic counter
show the precise average daily traffic volumes between Rathkeevin and
Cahir. In 2000, the average flow was 7623 vehicles per day. In 2001 the figure was 7808 vehicles per day.
According to the NRA National Roads Needs Study (published in 1998) a dual carriageway is suitable for use on a roadway where up to 45,000 vehicles pass daily
(see NRA table). Where traffic volumes of this order use the dual carriageway, the average speed of vehicles would be 10mph less than the speed limit (i.e. 50mph on a roadway with a 60mph limit) on the thirty most congested hours of the year. For the remaining 8730 hours of the year, the average speeds would be higher than this.
The NRA traffic forecasts for the N24 between Rathkeevin and Cahir are given in the National Roads Needs Study. Working off a benchmark of between 5500 and 7500 vehicles per day in 1995, an average daily flow for
the year 2019 was estimated to be between 12000 and 16000 vehicles per day, with the maximum in
year 2037 being between 13000 and 17000 vehicles per day.
Given the figures recorded at the Woodruff counter in 2000 and 2001, the lower estimates are proving almost 100% accurate, and there is no reason to believe that this will change.
As such, an average daily flow of 12,000 vehicles per day can be expected in
year 2019 and the maximum 35 years from now will be 13,000 vehicles per day.
The National Roads Needs Study recommends a different type of road where traffic volumes of this order are expected. A “Wide 2 Lane” roadway can accommodate almost 14,000 vehicles per day
(see NRA table).
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A wide 2 lane road would be more than
adequate
Where traffic volumes of this order use the roadway, the average speed of vehicles would be 10mph less than the speed limit (i.e. 50mph on a roadway with a 60mph limit) on the thirty most congested hours of the year. For the remaining 8730 hours of the year, the average speeds would be higher than this. Indeed, where a wide two-lane roadway is constructed to accommodate volumes between 8,000 and 12,000 vehicles per day (as the NRA predicts for this roadway), then the average speed of vehicles will be higher still.
For precise details on the NRA’s methods of forecasting traffic volumes and consequent selection of road types, the National Roads Needs Study (1998-2019) can be purchased from the government publication office for € 31.75.
We provide a brief summary here.
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