TfL to build fake tunnel for Aldgate track upgrade rehearsal
Ruislip Depot will host a temporary facility to prepare for a major summer 2027 junction closure.
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Transport for London (TfL) is planning to construct a temporary tunnel and platform at Ruislip Depot. This facility will serve as a rehearsal space for a significant track upgrade scheduled for the Aldgate junction, a complex railway intersection in Central London.
The Aldgate junction, located just north of Aldgate station, sees services from the Circle, Hammersmith and City, and Metropolitan lines crossing over each other. The District line also joins the Circle line south of the junction. The upgrade is a critical component of the Four Lines Modernisation (4LM) project, which aims to enhance services on London's sub-surface lines.
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Improving Capacity and Reliability
The primary objective of the Aldgate junction upgrade is to reduce track conflicts and increase the number of trains that can pass through the area. The project aims to enable 32 trains per hour to operate through the junction, a significant increase from current capacity. This enhancement is intended to reduce delays and improve overall reliability for passengers using the sub-surface lines.
The complexity of the junction, with multiple lines intersecting, frequently causes delays as trains must wait for others to clear the tracks. Plans to upgrade the junction were first announced approximately a decade ago but were put on hold in 2018 due to concerns over the risks associated with undertaking challenging works with an unproven delivery partner. The COVID-19 pandemic further delayed progress on these essential renewals.
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Rehearsal Facility at Ruislip Depot
To mitigate the risks associated with the major track renewal and redesign at Aldgate, TfL will build the temporary tunnel and platform at Ruislip Depot. This facility will provide a realistic environment for operator training and for testing specialised equipment, including Kirow cranes and tilting wagons, before the main works commence. The plans for the junction itself involve rationalising the track layout north of Aldgate station to reduce the number of diamond crossings and improve train movement efficiency.
Summer 2027 Closure
The scale of the Aldgate junction upgrade necessitates a complete closure of the junction. TfL anticipates this major blockade will occur in summer 2027, with August being the most likely period due to historically lower passenger numbers. The exact dates are yet to be confirmed and are dependent on the final approval of the project details and coordination with ongoing resignalling works in the area.
A TfL spokesperson confirmed that a comprehensive customer information campaign will be launched well in advance of the works, once all final details have been approved. Passengers using the Circle, Hammersmith and City, and Metropolitan lines should expect significant disruption during the planned closure.
Questions this report answers
+Why is TfL building a fake tube tunnel?
TfL is constructing a temporary tunnel and platform at Ruislip Depot to rehearse a complex track upgrade at Aldgate junction. This rehearsal aims to reduce the risk of errors and delays during the actual works, ensuring operator training and equipment testing are completed effectively.
+What is the Aldgate junction upgrade for?
The upgrade is part of the Four Lines Modernisation project to improve services on the sub-surface lines. It aims to reduce track conflicts and allow 32 trains per hour through the junction, increasing capacity and reducing passenger overcrowding and delays.
+When will the Aldgate junction be closed?
A full closure of the Aldgate junction is planned for summer 2027, likely during August. This period is chosen as it is typically the quietest time on the railway for major engineering works.
+How will passengers be informed about the closure?
Transport for London has stated that a full customer information campaign will be launched well in advance of the works starting. This campaign will provide details about the closure and its impact once the final plans for the upgrade have been approved.
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