Crossrail platform extensions - station design case study

21 April 2021
Image of Amey employees in PPE, carrying out work on a rail track.
When a platform extension project at three Crossrail stations fell seriously behind schedule, Amey Consulting was brought in to get the design process back on track.

Network Rail’s plan to introduce longer, 12-car trains for the new Crossrail route west of London meant that platforms at Slough, Maidenhead and West Drayton would have to be lengthened to increase capacity. Amey was appointed to design platform extensions at Slough and Maidenhead, plus the redesign of drainage, foundations and copper realignment works at West Drayton.

From the start Amey established a collaborative, multidisciplinary approach, with regular workshops to establish the construction team’s priorities and ensure designs were delivered in accordance with their schedule. As Amey was brought into this contract at a very late stage, it was vital for us to deliver our designs at the right time. Weekly meetings were held with the client team to review progress, address issues and agree any actions required. As a result, the client review periods were reduced to just five days as opposed to the normal 20-day review period, enabling the AFC (approved for construction) drawings to be issued in time for the planned construction windows.

One of the key considerations was to reduce the time on site required to complete the works due to limited possessions. To achieve this the team developed a pre-cast foundation design that could be manufactured offsite and in advance of the possession works. This provided several benefits such as reduction of in situ mass concrete, reduced onsite construction time and significant savings to the client. Another key benefit of this approach was reduced waste and environmental impact by efficient use of resources and materials.

The 3D modelling significantly streamlined the design process, helping to ensure that Amey’s M&E, telecoms, drainage and civil engineering designs interfaced seamlessly with those of the other disciplines. In particular we introduced 3D drainage and reinforcement BIM models, which are normally done in 2D plan view only. These models provided greater understanding of the designs during our meetings with clients and stakeholders, identifying potential clashes in time for them to be resolved.

Modular type platforms were considered for Slough island platform (3 & 4) and Maidenhead station platform extensions. While the modular platforms were designed by our subcontractor, Amey Consulting delivered all other designs (M&E, telecoms, drainage, civils tie in of modular platforms to existing platforms), ensuring they interfaced with the subcontractor’s designs through efficient use of BIM.

In addition to the main designs, Amey Consulting provided support functions in the form of an environmental management plan, geotechnical surveys and analysis, gauging analysis and coper alignment designs, overhead line equipment (OLE) interface checks, EMC (electromagnetic compatibility) requirements, and RAM (reliability, availability and maintainability) reports. The client provided information about the signalling interfaces and Amey ensured any signalling considerations were embedded into the relevant designs. 

Various factors had to be taken into account to ensure the safety and comfort of station users. For example, the width of the platform extensions had to accommodate the likely number of passengers at peak times. The measurements of all trains likely to stop at the stations had to be checked, making sure the stepping distance between train and platform was suitable for everyone – including people with pushchairs and wheelchair users.

The designs had to allow for clearly demarcated safe zones, with yellow lines and tactile paving to assist those with visual impairments. Lighting of the existing platforms and extensions needed to be consistent, and the noise levels created by additional passenger information speakers had to be analysed for their impact on the neighbourhood.

Overall, Amey Consulting succeeded in producing the required designs in line with Network Rail’s planned construction schedule, helping to claw back the costly time overruns.