The handrail was designed by Woodform in conjunction with main contractors Hawkins Construction, to meet the specific design parametres of the balustrade, while accommodating a fine detail LED lighting system to run the length of the handrail – a total of 160 metres, 80 metres on each side of the cycle way.
Creating two curved handrails to follow on opposite sides of the same bend presented a range of challenges. Rebates for the lighting system had to be routed on opposite edges depending on the which side of the cycleway the section was placed.
Not only were Woodform following the curve, but the balustrade is also on a slant meaning the inside edge on one side is lower than the opposite curve on the other side, giving a three dimensional element to the appearance.
The handrail was fabricated in 36 sections 4.5 metres long, approximately 120mm wide and 44mm thick, each bent to an exacting individual radius.
Bending a piece of timber 120 x 45mm thick to a radius required some creative thinking. It's impossible to bend timber on its edge, so Woodform had to take a a solid rectangular piece of timber of the required dimensions and cut it into three separate equally sized laminates, which was bent bent to the radius for both the internal and external rail.
Each laminate was then machined to be flat on top and curved underneath with two rebates routed the length of each piece: one to accommodate the LED lighting system and the other for the bolting system which fixed the handrail to the balustrade.
The laminates were then glued together in the true shape of the handrail. A routed groove was formed in each of the laminate line joins and filled with an aquatic caulking to prevent cracking or breaking at the glue lines.
The joins had to be flush. Stainless steel jointers were fixed so when the two pieces butted together a recess allowed the same caulking material to be injected providing flexibility.
Installation proved to be just as challenging. The bridge, which weighed more than 20 ton, was packed and moved according to the handrail profile so the handrail could simply sit on top of the balustrade before being bolted into place. A tolerance of less than 1mm in the rebates was necessary to ensure an accurate fit.
Finally the rail was coated with a protective oil to preserve the wood.