St Chad’s and Queensway Tunnels, Birmingham

The first stage of the project involved structural changes such as strengthening the central wall between the two carriageways, creating impact barriers and adding new escape openings.

A new LED lighting system was also introduced. The work necessitated 24 hour closure of the tunnels, whilst minimising the effect on city centre traffic.

The second half of the project also required 24 hour closures, with considerable local press coverage used to make commuters fully aware of the temporary disruption.

Responsible for major electrical power installations and refurbishment of the 40-year-old infrastructure, VVB was contracted by Amey, based upon experience with similar projects.

One of the most important upgrades was carried out on the ventilation system. 25 new ‘jet fans’ were installed by VVB along the length of the roof of the tunnels. These powerful fans were connected to air quality monitors and fire response systems, and remove smoke from the tunnels, allowing safe evacuation in the event of a fire.

To enable maintenance or repair of each fan, locally mounted isolators were installed in the roof of each tunnel. Due to the long distances involved in this project, the isolators were specially designed to accept oversized cables, necessary to prevent volt drop/power loss.

During the project, VVB also installed:

• 27 PA speakers
• 21 CCTV cameras
• 32 Vehicle detection cameras
• 48 Emergency phones
• 4 Digital variable message signs
• 160+Way-finder signs
• 7 Controlled evacuation doors
• 40+ miles of cable

To comply with the latest safety standards, all Mechanical and Electrical (M&E) equipment associated with the tunnel life safety systems needed to be fed by fire rated power cabling. In addition to this, 50% of the equipment is fed from an alternative power supply, ensuring that there is no single point of failure for the whole tunnel.