Eleanor Street inc. Adits

Following notification of access delays of over a year, as well as a six‑month delay to the main running tunnel TBMs, we were asked to consider alternative solutions. The proposal for a new temporary shaft saved the client over 18 months by the time the full site was available after relocating the existing incumbents. We agreed to undertake the original scope from the smaller shaft - using only one access point instead of the four originally planned for the larger shaft - at no additional cost.

This approach also allowed the Stage One concrete for the running tunnels to be installed ahead of schedule. Working in partnership, we collaborated on a temporary works propping scheme for the eight cross passages, enabling all connections to be constructed from the rear of the running tunnels.

Both solutions delivered critical time savings for Crossrail.

The shaft secondary lining of 16.4m diameter and 32m depth, including four tunnel openings, was originally planned as a day‑shift activity where all four openings could be worked on simultaneously using a full‑circle shutter. However, in order to carry out multiple tasks - tunnelling and tunnel lining - only one tunnel opening could be concreted at a time, with one area for steel fixing, one for tunnelling, and the final one for shutter operations.

Added Value Contributions from JGL

We re‑purposed the steel lining shutter to pour the lower section of the shaft in 9m‑high quadrants, enabling all workshops to continue operating. The shutter was redesigned as a 9m‑high quadrant with only 20 tie rods penetrating the sheet membrane through special tie‑sealing units. The lower 9m section was completed in a total of eight weeks.

The quadrant shutter was then dismantled on site and reconfigured into a 3.3m‑high full‑circle shutter. During these works, eight hydraulically linked strand jacks were installed over the shaft using the temporary works details previously utilised during shaft construction.

A weekend Section 61 dispensation was requested from the Council, allowing the full‑circle shutter to be installed over a single weekend.

Thereafter, the remaining seven lifts of the shutter were completed in two weeks and two days, without requiring removal of any shutter sections from the shaft. No work in the lower tunnels was stopped or hindered, as the shutter incorporated three protected decking levels, increasing both safety and material handling efficiency.