Safety Risk Assessment for Lightweight Gantries
The use of motorway gantries offers the potential for lower-cost installation of vital infrastructure for traffic management. Due to the lightweight construction, it's more likely that the gantry may collapse if struck by a vehicle and it was therefore important for the Highways Agency to test how drivers would react to a collapsing gantry, but in a safe and reliable manner. |
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TRL's Driving Simulator was an ideal solution as participants could experience such a collapse in realistic circumstances and their responses could be accurately recorded and evaluated. A test scenario was reproduced in the TRL Driving Simulator to evaluate driver behaviour in response to partial collapse of a lightweight gantry.
The gantry collapse was animated when the driver was within sight of the gantry, with a white saloon car veering off the motorway and crashing through the vertical support causing partial collapse of the gantry. The trial comprised an approximately 14 mile drive along a generic three-lane motorway with lightweight gantries added at approximate one-mile intervals along the entire route. The gantries were modelled to appear identical to that tested in the track trials, except that only one vertical leg was used in the verge, to avoid drivers noticing anything different about the gantry which collapses.
Results indicated that participants displayed a variety of behaviours in response to the gantry collapse. Age, sex and experience were not good indicators of the eventual behavioural response of the driver. Drivers' speed profiles fell into one of three categories:
- came to a stop
- slowed dramatically before continuing under the gantry at slow speed
- continued at high speed underneath the gantry.
Drivers' responses depended on the lane in which the vehicle was travelling at the time of collapse. Because of the absence of other traffic, most of the drivers (10 out of 24) were travelling in lane one. Of these 19 drivers, 10 stopped, five braked but then continued under the gantry, whilst four did not brake at all. Those in lane two all continued under the gantry. However, all participants reacted to the event by removing their foot from the accelerator.
For more information on this project, please contact Nick Reed on +44 (0)1344 770046 or nreed@trl.co.uk.
