Albrighton Bridge Temporary Works

The Challenge

The existing bridge deck was significantly deteriorated and required to be demolished and replaced without damage to the adjoining listed wrought iron Victorian footbridge and cast-iron parapets. This required AMCO to provide temporary support to the footbridge and parapets during the works whilst lifting bridge elements in and out with a 1000t crane. This all took place in a very constricted site with significant level change, numerous buried services and on the junction of a busy main road. 

The Solution

GGP Consult were appointed by AMCO Rail to provide temporary works designs for the following items during the bridge reconstruction:

• Support of the footbridge with a bespoke cantilever RMD support tower and kentledge
• Support of the bridge parapets and lineside cables with RMS support towers
• Design and position of the 1000t crane outriggers including verification of loads onto existing ground level and utilities
• Check of bridge abutment stability during the demolition and construction of the new bridge

To further the complexity of the temporary works, the footbridge foundations were built within an area of the railway bridge requiring demolition meaning simple propping would not suffice. A cantilever support tower was designed by GGP’s Structural Engineers requiring 20t of concrete kentledge to prevent overturning. Deflection checks of the support tower were carried out to ensure the footbridge would not defect during the works causing damage. 

Due to the minimal space available and size of crane required to lift the new bridge all temporary works were required to work in unison without clashes. The 1000t crane was positioned within a few inches of the footbridge support tower. The positioning of outriggers in a very restricted space with cross fall and utilities to avoid was critical and required accurate surveying and drawing of the bridge and surrounding area. 

To achieve the required level of accuracy, 3D laser scanning and Ground Penetrating Radar were used for creating accurate detailed drawings and locating services. 

The Result

The bridge was successfully replaced during a series of weekend possessions without any damage to the listed Victorian structures, road or utilities.