Constructive Consultancy
Wilford Suspension Bridge, Nottingham
In 2008 Constructive Consultancy was appointed by Severn Trent Water to carry out a principal inspection, dimensional survey, capacity assessment and refurbishment scheme design for the Wilford Suspension Footbridge which spans 70 metres over the River Trent in Nottingham following concerns about the safety of this Victorian Listed Structure.The suspension bridge forms a key transport corridor for pedestrians travelling from the car parks used by football and cricket supporters to the grounds of Nottingham Forest FC, Nottinghamshire County FC and Trent Bridge as well as for the Robin Hood Marathon and various riverside events. There were no records for the structure so our team of Engineers prepared as-built drawings for the structure using traditional and remote laser scanning survey techniques before using the data to record structural defects for later use in the assessment. The structure was inspected using rope-access, diving and confined spaces teams.
The inspections highlighted the possibility of internal corrosion to the suspension cables, so radiographic and magnetic flux techniques were used to establish the extent of corrosion to the cables to assess cable capacity.
The structures flexible design and frequent crowd loading from both walkers and joggers required our assessment to take account of the extremes of loading that the structure would experience which required development of loading models which were more onerous than that advised in codes of practice. To find the true load effects on the structure we modelled the structure and the applied loads using both static and dynamic finite element analysis models.
Our capacity assessment concluded that the structure was in need of a major refurbishment including the replacement of the timber deck, re-painting and strengthening of a number of corroded members.
We have recently prepared the major maintenance scheme design for the structure and will be supervising refurbishment when it commences in May 2009.
