The NRA currently requires safety barriers be used to protect the motorist from hazards alongside the national road network where the design speed is 85km/h and above. Many National Secondary Roads are located in tourist areas of outstanding natural beauty, where the existing roadside boundary is generally hedgerows and stone walls. Concerns exist with regard to the extent of safety barrier required on these road realignment projects routes: current requirements are specified in NRA standard TD 19. There is a requirement to develop a low-cost low maintenance alternative to existing proprietary products currently on the market. There are also concerns that the current barrier products are inappropriate for use on these roads and that it would be desirable to develop more environmentally sensitive, aesthetically pleasing solutions without compromising road safety. The alternative product or works could be incorporated into the NRA Standard Details. As part of the research, it is anticipated that an earth bund would be investigated as a possible low-cost alternative to existing barriers. The proposed system would have to comply with existing European Standards, in particular, EN 1317 Part 2.
The research involves the investigation of the safety barriers used on the Irish National Secondary roads. The objective is to achieve low cost and more aesthetically pleasing options to existing proprietary safety barriers for National Roads upgrade projects located in scenic areas. The edge protection solutions must comply with the relevant European Standards, namely, EN 1317 Part 2 and the performance standards required in NRA DMRB standard NRA TD 19/09.
A new gabion barrier prototype was developed and investigated but the tests resulted in a failure due to the rollover of the vehicle and tearing of the gabion mesh yielding a large working width. It was found that although the system potentially has the necessary mass to contain a vehicle, the barrier front face does not have the necessary stiffness and strength to contain the gabion stone filling and hence redirect the vehicle.