My project

Construction ran between February and August last year. The pathway is being built for the local authority by the London Development Agency - a condition of its planning approval for the development of the adjoining industrial area for the relocation of small businesses from the Olympic Games site.

Until these developments, the bank on the southern side of Mossops Creek was industrial with a concrete oversite, CCTV cameras, security lighting, security fencing and razor wire. On completion of the river walk in July, an ecologically-friendly bank and a new conservation area, will have transformed the site.

Mossops Creek itself is not a natural waterway but is the last remnant of a large and ancient gravel pit.

The backfilled areas of it are now industrial development areas with the buildings supported on piles founded on the clay at the bottom of the old pit. Additional development by the LDA and GLE will see small businesses from the Olympic Site at Hackney being offered new accommodation here.

The bridge was originally designed as a ‘tied-arch’ structure assuming that the longitudinal horizontal thrust of the arch would be taken out by the suspended deck structure and hence not be transferred to the fill material in the old gravel pit. But the curved deck proved to be unsuitable for tying the arch and so the footbridge was re-designed as a ‘pin-ended arch’ with the horizontal thrust being provided by vertical pile groups within the fill and embedded in the underlying clay stratum.

A sensitivity analysis was carried out for a range of possible lateral spread movements of the pile groups and these indicated a low sensitivity to such movements with stresses well within capacity of the bridge structure.

The bridge’s design specified two steel support arches either side of the suspended deck. These arches lean towards each other at an angle of 70 degrees to the horizontal and are braced together with three struts about the apex of the arch. The arches are also tied together at deck level to form a robust and stable framework for supporting the deck.

For aesthetic reasons, and to give a robust appearance, Enfield required the arch members to be a size that was well in excess of the design requirements. The stainless steel hangers were oversized for similar reasons. The hand-railings are bespoke - to add interest to the elevations - and a similar railing design has been used on a adjoining ramp structure. Furthermore, unacceptable lateral oscillations of the bridge deck have been prevented by welding the deck structure to the tie members between the arches.

The bridge is protected with aluminium spray, an epoxy sealer coat, two epoxy primer coats (first being an MIO-based coating) with an acrylic polyurethane gloss finish. A salmon pink finish coat was chosen to ensure that the finished footbridge stands out against the surrounding vegetation and provides a well-defined reflection in the waters of the creek.

It was designed by Enfield Council’s Highway Services Centre and fabricated by steelwork specialists, Allerton Bridges Limited. The foundations, access ramp and abutments were constructed by A H Nicholls & Sons who were Enfield’s Civil Engineering and Term Contractor at the time. The 22.2m span bridge will be opened to the public in July with over 10,000 people expected to use it each year.