Tunnel Traffic Controllers

SSL have had a great deal of experience of providing systems for Tunnel Traffic Control and in deploying tunnel traffic and tunnel environmental control systems. This is quite an esoteric area of HA work, which calls for highly reliable software and electronics. Tunnels are hazardous for motorists and this is complicated by the fact that Tunnels are often a constriction in traffic flow due to the fact that they are expensive to widen. The confined nature of tunnels and the need to close bores during maintenance whilst keeping traffic running adds additional challenges to any work carried out. During the course of our tunnel activities we have become very familiar with the ingredients making up a Highways Agency Tunnel and the special requirements associated with bringing them all together under one 'roof'. In particular, BD78/99 the DMRB and the IEC 61508 requirements.

A38 Saltash Tunnel Traffic Controller
This system is described in detail : please see Tamar Bridge Tidal Flow System .

M25 Holmesdale (and Bell Common) Tunnel Traffic Controller
Currently this M25 Tunnel Traffic Controller sets a range of VMS on the approaches to the Holmesdale and Bell Common Tunnels of the M25 to provide contraflow and bore closure during maintenance. The tunnel controller OIF is located at Chigwell PCO. SSL are upgrading this tunnel traffic controller to link to the RCC COBS as a COBS Tunnel Subsystem.

A12 George Green Tunnel and Green Man Tunnel Traffic Controller
The Hackney Tunnel Traffic Controller monitors the state of the George Green and the Green Man Tunnel on the A12 and automatically sets message signs and matrix signals to advise the motorist of hazards in the tunnel including pedestrians in road, queues, carbon monoxide, fire alarms, obscuration alarms MIDAS alerts etc. It automatically sets matrix indicator, message signs and plank VMS in the event of a detection of a tunnel hazard.

The tunnel controller OIF is located at Blackwall PCO.

A406 Fore Street Tunnel Traffic Controller
Similar to the Hackney Tunnel Sign Controller - it monitors the state of Fore Street tunnel on the A406 and automatically sets message signs and matrix signals to advise the motorist of hazards in the tunnel. The tunnel controller OIF is located and operated at Blackwall PCO.

The separate MIDAS (Motorway Incident Detection & Automatic Signaling) interface is used to connect the TSC's to the MIDAS outstation. The MIDAS outstations are used to detect traffic queues in the tunnel. Automatic plans are set if significant queues are detected.

The Tunnel Control Systems have all been designed and implemented by SSL in response to HA requirements.