06 OCT 2015

BakerHicks designs safe and robust temporary foundation solution for Seabraes footbridge

Facilitating installation of 56m-long steel bridge

Multidisciplinary design and engineering company, BakerHicks, formerly Morgan Sindall Professional Services, has provided complex temporary works design to Saebraes' new 56m-long footbridge. The designs and associated safety checks were required to build the bridge safely, within a tight timeframe and to ensure the bridge would fit into a space with only a couple of millimetres margin for error.

The single-span steel bridge which crosses the East Coast railway line near Dundee rail station, is equivalent in length to half a football pitch, and was assembled and installed in a prepared area adjacent to the railway in just eight weeks.

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A specialist 1,750-tonne crane was used to lift the 80-tonne bridge section into place. The crane foundation was designed as a bespoke 600mm granular working platform comprising of two layers of geotextile. The platform was installed in 75mm layers, ensuring the completed platform was well compacted and any potential deflection risks were minimised. This provided significant cost savings, as it removed the need for expensive piled foundations.

The crane was used to lift the steel structure into place in a procedure that took around two hours during a rail possession. The bridge was slotted exactly into place with just millimetres of leeway at either end.

Martin Reader, director of temporary works, says the temporary works designs and checks for the crane foundations needed to adhere to Network Rail temporary works certification protocols when working adjacent to a ‘live’ railway:

"The team’s attention to detail, particularly when designing in poor ground conditions, ensured settlement control and safety were at the forefront of everyone’s mind. This scheme shows how our regional offices have collaborated to provide a robust and safe solution for the site team, the public and train operators."

Now complete, the bridge gives pedestrian, disabled and cycle access to the River Tay waterfront from the north of the town, meaning visitors can avoid a 1.5 km detour around the rail line.

The bridge also aligns with the recently constructed steps at Seabraes allowing for direct connection through the Seabraes development sites to the University of Dundee campus. Footpath and cycleway facilities also permit connections to Dundee City Centre and the popular west end residential district.