Source: https://tendernation.io/opportunities/01a13d20-5407-73e4-b677-93bb4654ba31/wp1140-t5d-design-consultant closed GB open procedure Suitable for SMEs # WP1140 - T5D Design Consultant [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 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 within 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 others (Employed by the Client) under the direction of the Design Consultant ### Item Question Q1 Do you have experience with Underground rail network ventilation resilience? Requirement: Ventilation Resilience Report required for the HAL Rail underground network. Q2 What capability do you have of air flow modeling for fans / attenuators etc.? Requirement: Model the existing configuration with one fan operating, and both fans operating and then repeat the modelling with shaft sub divided to allow one set of attenuators to be replaced while the other is operational. Q3 What capability do you have of understanding the requirements for specifying replacement attenuators etc., Specifically considering the constraints of an operational rail network? 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/abb75190-6054-4f95-b2a7-26ec9ecfbe8d) 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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