Blackhorse Lane Bridges Reconstruction

Originally, Victorian bridges were built 130 years ago to support horses and carts. However, with the invention and expansion of motor vehicles throughout the decades, the bridges became decrepit. This scheme will protect the lives of hundreds of civilians crossing over and under both Blackhorse Lane Bridges. 

Originally working separately for London Trams on the South Bridge and Croydon Council on North Bridge, we considered the benefits of a joint scheme. We advised our clients to combine the two construction projects into a single scheme, thus saving significant time and money through the sharing of information, joint traffic management and utilities diversions, common site mobilisation and enabling works, shared site activities and equipment and economy of scale in design. This improved likelihood of securing funding and reducing the construction impact and disruption.

Upon assessing risks associated with the bridges, the clients were advised to close the bridges until further design and future reconstruction. This was due to the immense deterioration of the existing cast iron beams, with a risk of South Bridge over tram line collapsing under its own weight.

Immense deterioration of the existing cast iron beams, with a risk of South Bridge over tram line collapsing under its own weight.

Halfway through the concept design, the South Bridge crossing over the tram line posed risk of structural collapse and imminent danger. This required our specialist services to come up with a part-demolition interim measure solution, under a carefully controlled construction process to reduce the structural stress and make the structure safe until the eventual reconstruction. The works included load testing/ structural monitoring during demolition.  

To manage risk, we undertook a comprehensive feasibility study and risk assessment to establish means of mitigation. The part demolition activities followed whilst we proceeded with the concept design of the two bridges. As a result of our early developments within the scheme, the project expanded to include the road widening of the Blackhorse Lane and inclusion of a cycle route along the bridge, for which we carried out feasibility study and subsequent concept.

Dealing with historic infrastructures often raises significant cross utility issues. Our studies highlighted millions of pounds worth of utilities passing through the bridges, such as BT fibre optics, gas, water, and electrical voltage cables that upheld services within the area. These utilities increased construction risk and removed the option of fast single stage demolition to rebuild the deck. To overcome the stakeholder issue, we conducted early consultations with utility owners and made allowance in the budget and construction programme to inhibit miscommunication and delays.

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