Based on a cantilever A-frame, precast prestressed concrete sign gantries are set to create distinctive roadside landmarks. Conceived principally by the Prestressed Concrete Association, C V Buchan and Tarmac Precast Concrete, the new design provides an alternative to current reinforced concrete and steel structures, and is both more architecturally pleasing and cost-effective. Importantly, compared with steel gantries, the new gantries are virtually maintenance-free as well as offering ease of transportation and installation.
The A-frame supports an inverted-U prestressed concrete gantry beam. With a maximum thickness of just 750mm, the frames have an efficient slimline profile. Manufactured from C60 concrete, they can be provided in varying heights and in demountable form, to allow for relocation, or pocketed for more permanent fixing.
The key to the compact size of the frame lies with the beam/ column connection, which has eliminated torsional stresses within the column. The beam is effectively simply supported in the vertical and horizontal planes. The gantry beams range in span from 14m to 37m and are also manufactured with C60 concrete. Prestressed and with light secondary reinforcement, they offer major savings compared with conventional reinforced-concrete box- beam construction.
Able to accommodate various sign and matrix arrangements, the new sign gantries have been in high demand since their introduction and have been ordered for the A1(M) widening at Alconbury, Peterborough, and the A1- M1 link, south of Leeds.
OWNER Road Management Services Yorkshire Link
CONSULTING ENGINEER Brown and Root/ Howard Humphreys and Partners, Babtie Group
CERTIFICATION OF DESIGN FOR PROJECT
Pell Frischman Consultants
CONTRACTOR rmg Construction JV, Kvaerner/Balfour Beatty JV
SUPPLIERS C V Buchan, Tarmac Precast Concrete
OTHER Prestressed Concrete Association