Source: https://tendernation.io/opportunities/01a13d23-6641-7198-ad5c-b2a0070c0ece/wp6235-t5d-mep-subcontractor closed GB open procedure Suitable for SMEs # WP6235 -T5D MEP Subcontractor [Costain Limited (H7-Heathrow)](https://tendernation.io/buyers/costain-limited-h7-heathrow) Estimated value £2,500,000 to £5,000,000 Published 2 Jun 2026 Deadline Closed 9 Jun 2026 ## Who can bid - Buyer says suitable for SMEs The buyer ticked “suitable for SMEs” on the notice. Anyone can still bid. - Buyer says suitable for VCSEs The buyer ticked “suitable for voluntary, community and social enterprises” on the notice. - Open procedure Anyone can submit a full tender; there is no shortlisting stage. [More contracts for small businesses and VCSEs](https://tendernation.io/opportunities/for-small-businesses) ## About this tender ### Expression of Interest T5D MEP Subcontractor ### T5D Attenuator Overhaul (Survey / RIBA 4iii) Scope The T5D Rail-tunnel Ventilation Shaft is located adjacent to T5D at its North and can be accessed from the bottom (Level 6) via the trackside of the HEX tunnel or from the top (level 7) via Airside. The objective is to replace the four attenuators in the T5D Shaft because they are at their end of life. The renewal of the T5D attenuators aims to reduce the risk of debris entering fans, tunnels and station, prevent the fans from failing in any fire scenario and provide ventilation and smoke clearance for the Heathrow Rail Tunnels. This improves safety conditions in Heathrow Rail Tunnels and improves resilience of systems. In addition, less maintenance and repair are required for the attenuator. Each attenuator is formed of four quadrants weighing around 1160 kg. Review MEP systems along the airflow and advise replacement/modification to bring them up to compliance. Surveys will be carried out by MEP Subcontractor under the direction of the Design Consultant (Employed by the Client). ### Item Question Q1 What capability do you have of understanding the requirements for replacing attenuators etc., considering the constraints of an operational rail network? Q2 What capability do you have of carrying out a survey of the T5D Shaft during non-operational hours to provide all the information required to complete the RIBA 4ii design by the Design Consultant and the RIBA 4iii by the MEP Subcontractor? • M&E Services within the air path • Fan and Attenuator • Structure Note: - RIBA 5 onwards including construction is excluded. Read full description ## CPV classification Engineering design services Source Contracts Finder (UK) [View official notice](https://www.contractsfinder.service.gov.uk/notice/de6c09f3-6c96-4020-b334-051d5fc03d1d) Never miss a tender like this again Get AI summaries, deadline alerts and a bid pipeline for tenders matched to your business. Free to start. 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