Road design report says fuel savings possible

A space shuttle could be launched every week using fuel saved by motorists using the most efficient route for a proposed 12km bypass in Co Waterford instead of the least efficient, an EU energy study has found.

In the light of these findings, the National Roads Authority (NRA) plans to incorporate an energy efficiency analysis as part of the environmental assessment on selected new road projects.

The results of the Integration of the Measurement of Energy Usage in Road Design (IERD) study under the EU Save programme are "staggering", according to NRA engineering inspector Donal Clear, who observed the research.

Transport accounts for more than 80 per cent of the energy consumed in Europe and faced with sharply rising oil prices and Kyoto targets, the Directorate-General for Energy and Transport commissioned the report to examine the impact of road design on energy efficiency.

"If you take the route we used as an example in Ireland, the N25 Dungarvan bypass, the difference between the most efficient and least efficient of the five options considered was massive."

The energy efficiency of the five different N25 routes was compared for the EU study. Similar comparisons were carried out for planned roads in France, Portugal, Sweden and the Czech Republic.

"For the layman, it is the equivalent of launching a shuttle into orbit every week. Multiply that out over a 20-year lifespan of a road and the differences become absolutely enormous," he said.

"Waterford Co Council is designing the N25 and the different options varied in length from 11.43km to 13.13km.

"The results we found on the N25 were consistent across the EU. The energy savings between different designs can be literally staggering," says Mr Clear.

The research brought together engineering experts in road design, energy evaluation, geotechnology and IT. This led to the development of "Joulesave", a computer programme that works with existing road design software to allow engineers analyse the anticipated energy consumption of vehicles using each of the proposed route options. Road efficiencies come from reduced gradients, road surfaces with lower friction and layouts that reduce the amount of sudden acceleration and braking required.

"The changes in an individual vehicle are small, but multiplied across the thousands of vehicles that will use a route every day, and they become very clear.

"Gradients have a significant impact on energy efficiency and a reduction of vertical gradients improves this efficiency."

While ecological rather than energy considerations are expected to determine the final route of the N25, in view of the report's findings, the NRA plans to run energy assessments on greenfield routes on a pilot basis.

The report was submitted to the EU in recent weeks.

"At this stage it is unclear what the EU will do with the data. They might include it as a legal requirement in an EIS to carry out an energy efficiency survey in the same way that a myriad of different factors are examined such as the impact noise," said Mr Clear.