Blackhorse Lane Bridges re-open

In February 2020 the final barriers on Blackhorse Lane have come down and the two bridges are now open to both pedestrians and to vehicles.

This article gives some information an the reasons why the two bridges were closed to cars and lorries; why both bridges were replaced in one go; the additional problems that the contractors encountered; the improvements made to the bridges and to Addiscombe Railway Park, a part of which was closed whilst the works were undertaken.

Background
The Blackhorse Lane Bridge project covers two former railway bridges: Blackhorse Lane Bridge, owned by TfL and crosses the tramway, having been transferred from Network Rail in 2013; Addiscombe Park Bridge, owned by LB Croydon, transferred to Croydon Council following the closure of the Woodside to Addiscombe Station railway line and the building of Blackhorse Lane Tramstop.

Both bridges were constructed in the 1800s. In 2016 they were found to be in poor condition, especially the Transport for London bridge over the Tramlines, which was made with cast iron. Although strengthening works to the bridges was considered, this was deemed uneconomical. Instead, TfL and LB Croydon developed concept designs for a replacement of each bridge and to secure the necessary funding to carry out the works.

A collaborative working agreement outlined TfL’s responsibility to deliver the design, construction and commissioning of both bridges on Blackhorse Lane. In addition, LB Croydon needed to acquire land from three land owners in order to accommodate a new cycle path on their bridge. TfL agreed to manage the detailed design and construction of both bridge replacements to gain time and cost efficiencies and reduce cumulative disruption caused to local residents and businesses by undertaking the work separately.

In an aim to keep Blackhorse Lane open to vehicular traffic Transport for London employed various measures to enforce its weight limit. Unfortunately the rules were regularly being ignored by drivers and so, working with LB Croydon, in August 2016, the bridge was completely closed to vehicular traffic due to the deterioration of the existing cast iron beams, with a risk of TFL Bridge over tram line collapsing under its own weight. A temporary pedestrian and cyclist walkway was installed.

There were several complexities that had to be considered while finalising the longer- term option for Blackhorse Lane bridge, including:

• Restricted access
• The tramway underneath
• Residential properties close to the work site
• Third party cables and utilities on the bridge
• Funding the project: as both TFL and Croydon Council needed to be able to fund their share of the project

Options to strengthen the existing bridges were considered but this would still have caused significant disruption and would not have been cost efficient as they would still need to be replaced later on.

The improvements included widening one of the bridges to include a cycle path, in line with the Healthy Streets approach.  It was decided to replace the two bridges in one joint project to save public money and to reduce disruption. 

During the initial investigations and enabling works a number of unforeseen issues were encountered, for example, the team working on the Addiscombe Railway Park Bridge discovered a Victorian sewer system which was not detailed on any plans for the area.  This has led to delays in the design phase of the project while new engineering solutions were drawn up by the contractor.

Dealing with historic infrastructures often raises significant cross utility issues. The contractors found that millions of pounds worth of utilities passing through both 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.

The northern end of Addiscombe Railway Park, from Dalmally Passage to Blachorse Lane, also had to be closed from 2017 as the only safe access to the two bridges for heavy work vehicles was via the park. Due to the high level of vehicle movements it was decided that it was too unsafe to keep this section open.

As part of the consultation process with residents and the Addiscombe Railway Park Friends Group

Project timeline
August 2016
• Both bridges closed to through traffic for safety reasons. At this time the bridge repairs were expected to be completed in December 2018.
May 2017
• Interim works to reduce the weight of the TfL bridge in the short term to ensure the safety of the tramway underneath. This was complex work given utility pipes and cables running across the bridge, and they also need to be incorporated into the new bridge.
• Pedestrian and cycle bridge installed to maintain access for local residents
2016 – 2018
• Funding secured for both bridge replacements
• Legal agreements reached with TfL/LB Croydon
• Tendering completed
• Design work started
• Discussions with utility companies held to agree on diversions and reinstatement of major utilities
February 2018
• Design and build contract of both bridges awarded to Morgan Sindall
October 2018
• To address security concerns lighting improved across the site and on the walkways with patrols operating 24 hours a day

February 2019
• Public drop-in session held locally to answer questions about the project and advise the community about upcoming noisy work
• Installation of ground anchors into the earth to support each new bridge structure. Sheet piling and drilling with significant noise disruption. Installation of ground anchors to strengthen the bridge abutments.

April 2019
• Major demolition work and reconstruction of the east section of the bridges, with new bridge beams installed during an Easter nine-day suspension of tram services between Addiscombe and Beckenham Junction/Elmers End.

August 2019
• Further major demolition work and reconstruction of the west section of the bridges, with the final beams being installed during a ten-day suspension of tram
services between Sandilands and Beckenham Junction/Elmers End.

December 2019
• Blackhorse Lane reopened to single lane one-way traffic

Tuesday 25 February 2020
• Blackhorse Lane reopened in full

Monday 9th March 2020
• Addiscombe Railway Park northern section re-opens to the public. Now possible to walk or cycle from Blackhorse Lane to East India Way.
• Improvement works to the paths include resurfacing of Dalmally Passage; installation of new drainage and raising the level of the path to avoid flooding of the pathway near the bridge; digging out a new pond near the bridge for the newts and frogs; resurfacing of entire length of the footpath in the northern section of the park.