Current regulations require the fitment of sideguards, and front and rear underrun protection to new goods vehicles and trailers over certain weights. The front and rear underrun protection is to prevent cars that collide with the goods vehicle running under the structure of the larger vehicle. The sideguards are designed to protect pedestrians and cyclists from falling under the vehicle wheels, rather than prevent underrun from other vehicles, although they do provide some protection against this.
Regulations also require the fitment of spray suppression equipment to goods vehicles. These devices consist of wheel guards, mudflaps and matting.
The UK Department for Transport (DfT) has commissioned TRL Limited (TRL) to investigate the benefits of taking an integrated approach to these topics. If further improvements to these systems are considered individually the improvements in each area may appear small. However, an integrated approach to the design of the front, rear and side of HGVs may yield much greater combined benefits at less cost than considering the elements individually.
The main objectives for this study were to assess the benefits of integrating front, side and rear underrun protection in terms of:
Improved protection for other road users in collision with an HGV.
Allowing the use of improved aerodynamics to control spray emission in wet conditions, including the development of a regulatory test procedure.
Improved fuel efficiency as a result of improved aerodynamics.
The work on safety guards in this study has focused more on side protection than front or rear because improvements to these features were being considered in a parallel study commissioned by the European Commission (EC): Vehicle Crash Compatibility (VC_COMPAT).
The project was structured in two elements. The safety guards element included a review of current regulations and vehicle exemptions, computer simulation and assessment of the potential benefits of improved sideguards, and investigation of the issue of tractor/ trailer height compatibility and the potential benefits from the use of alternative materials. The spray suppression element in addition included a windtunnel assessment of different spray suppression methods, development of a test method which could be used as a regulatory test procedure, and comparative spray testing of standard and aerodynamically enhanced HGVs followed by fuel economy testing of the same.
This report contains detailed results from each element of the project. A cost benefit analysis was completed which is reported separately in TRL report PPR071.

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