FAQs
Why can't the track be lowered, or raise the height of the bridge to allow the wires to run under the original bridge?
Lowering the track:
This work involves lifting the track and excavating the ground to lower the ballast and track bed. Following surveys of the ground conditions at the site, they were deemed not suitable due to the heavy presence of rock in the area.
We would also need to lower the station platforms.
Raising the height of the bridge:
Jacking the structure would cause the approach pathways onto the bridge to be significantly steeper to connect to the heightened structure, making the structure and its approaches less accessible.
When will the bridge be installed?
The new bridge will be installed during an 8-hour City Line closure starting on the 25th August and finishing on the 28th August 2023.
When will the new bridge be open?
The new bridge is planned to open to the public on the 4th September 2023.
Why was there a 6-month period between the original bridge being demolished and the new structure being installed?
The design stage development, review and approvals process take approximately 12-15 months for a simple sanction/ design.
The replacement scheme will take 13 months to complete, starting in July 2022 with the outcome of the option selection activity, and ending in August 2023 with the installation of the replacement structure.
Alongside other teams requiring access to the line to carry out additional transformation work in the area, including platform extensions at Fairwater station and the installation of Overhead Line Equipment.
The team require full access to the line to install the new bridge, due to the machinery and road-rail vehicles required to lift the new bridge into place. This installation needs to be completed during a ‘possession’ of the track, where the line is closed to passenger services during both the day and the night.
The upcoming 8-hour City Line closure which begins on the 25th of August will be utilised to install the new bridge.
How will the bridge be installed?
The new bridge will be installed by rail-crane that will be situated in the proximity of the bridge at track level. It will be delivered to the site by rail in 2 to 3 sections. Due to space restrictions at the site, the design needed to be able to be constructed elsewhere and put together on-site, limiting the impact on rail services through Danescourt, and minimising the need for longer-term rail closures and disruption to lineside neighbours.
Off-site construction methods are particularly suited to footbridge construction, where overbridge elements are delivered to the site as a complete element and lifted into place by a crane.
Off-site construction minimises the amount of time needed to maintain a presence on-site. Site activities often require smaller worksites for most of the build and a smaller workforce. Due to the space restrictions of the site, constructing as much as possible off-site helps to manage site constraints.
Why do the sides of the bridge need to be 1.8m high?
For existing bridges over lines that are to be electrified, the Network Rail standards require that parapets on the bridge must be imperforate, climb-resistant, and at least 1.8m high. They also must have an anti-climb coping on top, for example, the top of the parapet should be pointed.
Will the new bridge be higher than the existing bridge?
The original bridge had a clearance of 4320mm from the track level to the soffit of the structure. The new structure has a clearance of more than 5025mm, allowing the appropriate clearance from OLE.
Why can't glass be installed on the bridge to improve visibility?
As the team want to ensure that a new bridge is installed in August 2023, the designers have been working to extremely tight timescales. Due to this, a standard design has been chosen, allowing for the design, fabrication, and installation of the new bridge to be completed by the beginning of the Autumn school term. A glass structure would need to be bespoke in design, which would incur significant delays and costs to the programme.
There are also long-term maintenance risks associated with the use of transparent glass or plastic panels that have been considered in the design. There is a risk that the panels would be graffitied, damaged, or scratched shortly after the installation, and would require ongoing maintenance.
What alterations have been made to improve visibility on the bridge?
The design includes a mounted lighting plate on the bridge to improve visibility.
We are also working closely with the local authority to ensure the bridge is safe. This includes discussions around additional CCTV.
We have also widened the pathway and approaches on the Beale Close side of the bridge, to improve visibility of those approaching the structure.