MSP-Maunsell/ Foster & Partners/ Pearce Traffic
Gantry systems capable of being readily adapted to future developments in materials and signing technology emerged as central themes to the solutions developed by the Maunsell/
Foster team. The resulting system is a family of lightweight structures made up of a mixture of steel and composite materials produced by a fully integrated team of engineers, architects, materials and lighting/signing experts.
These were developed for simplicity and flexibility. The use of light weight composites is intended to make them easily transportable. Designs were kept simple to reduce the visual intrusiveness of the gantries in recognition of the fact the number of these structures is expected to multiply significantly as traffic volumes increase.
The gantry beam is a Vierendeel frame with signs interspersed with louvred cladding chosen to emphasise the horizontal line of the structure and make signing easier to follow.
At the roadside, supports are set far enough back from the road to avoid the need to cater for high impact loadings. Central reservation supports are protected by a concrete barrier in preference to sacrificial support member. The team decided that as many accidents occur in severe weather conditions, loss of stability resulting from a collision with the support could still cause their structure to collapse.
The team also developed a plan for a retractable ladder which could be pulled down from the top of the gantry for maintenance access.
Proposals for the signs exploit developments in lighting technology with a view to simplifying the signalling system. Signs will be back lit by a light box typically illuminated by three polycarbonate tubes with remote light sources instead of a configuration of large numbers of fluorescent tubes.