In 2005, TRL crash-tested a prototype of a lightweight gantry (LWG) as part of a Highways Agency research project to find out whether a lightweight gantry could be used on motorways. The gantries presently used in the UK are substantial due to the impact loading they are designed to withstand in a collision. The Highways Agency 10-year plan involves the use of Active Traffic Management and the deployment of large numbers of variable message signs (VMS). TRL were asked to develop a safety assessment tool to be used to evaluate road safety during and after the installation of VMS using LWG and for testing driver behaviour during gantry collapse on a motorway. The prototype was an aluminium Lattix gantry from Juralco. The project identified five aspects for investigation: total weight and cost of the LWG structure; feasibility of developing a totally safe LWG; reduction of injury risk for passengers during crashes with the LWG; possibility of quick removal of the LWG; and quick time and cost effective installation process. Tests showed that the weight of the VMS would have to be reduced for the gantry not to collapse onto the carriageway after an accident. In crash tests, the LWG remained standing even after one leg from the nearside A frame had been destroyed.
Abstract