Design Consultant for T5D Rail Tunnel Ventilation Shaft Attenuator Replacement

Heathrow Airport Limited seeks a Design Consultant to lead the replacement of four end-of-life attenuators in the T5D Rail-tunnel Ventilation Shaft. The shaft is located adjacent to T5D at its North entrance, accessible from Level 6 via the HEX tunnel trackside or Level 7 via Airside. Scope of Work: - Review and advise on MEP system modifications to achieve compliance along the airflow path - Conduct airflow modeling for fans and attenuators under three scenarios: existing configuration with one fan operating, both fans operating, and shaft subdivided configuration allowing phased attenuator replacement during operational hours - Prepare a Ventilation Resilience Report for the HAL Rail underground network - Specify replacement attenuators while accommodating operational rail network constraints - Surveys will be conducted by client-employed personnel under your direction Required Expertise: - Demonstrated experience with underground rail network ventilation resilience - Proven capability in airflow modeling for fans and attenuator systems - Understanding of attenuator specification requirements within operational rail environments Objective: Replacing these attenuators will reduce debris ingress risk to fans and tunnels, prevent fan failure during fire scenarios, ensure effective ventilation and smoke clearance in Heathrow Rail Tunnels, enhance safety and system resilience, and reduce ongoing maintenance requirements. Each attenuator comprises four quadrants weighing approximately 1160 kg. Note: RIBA 5 onwards including construction phase is excluded from scope.