As England's second city, Birmingham is heavily reliant on the efficient flow of its traffic network. This is particularly acute for Birmingham as it lies in the heart of the heavily built up and densely populated West Midlands and is encircled by three motorways. Known as 'The Birmingham Box', the M5, M6 and M42 motorways are also vital links in the UK's road network, converging on Birmingham from London, Manchester and Bristol and providing vital North-South and East-West routes. Between them they carry over half a million vehicles every day and any problem can rapidly escalate into a major traffic nightmare. Monitoring and managing this motorway network is the Highways Agency (HA), who rely on a network of cameras to see where traffic is building up, where accidents have occurred and where diversionary action needs to be taken. With such high dependency on the Birmingham Box, the HA could not afford downtime or inefficient operating systems and, therefore, embarked on a £1.9m overhaul of their surveillance network. AMG was chosen to develop a new network that would cope with traffic flows now and in the future - the Birmingham Digital Ring.

AMG installed its Guardian 2800 multi-channel video transmission system to link four motorway transmission stations at Ray Hall, Bromsgrove, Umberslade and Coleshill with the Police Control Office (PCO) at Perry Barr and form the Digital Ring. Using an existing dual fibre optic ring, capable of transmitting live, full bandwidth video images from 160 of the hundreds of cameras positioned anywhere on the network. The uncompressed video allows the PCO and the Highways Agency's Regional Traffic Control Centre real time monitoring of traffic flow around the entire West Midlands region. Critically, in the event of a break or catastrophic damage to one of the fibre optic cables, the AMG equipment allows the video and data on the network to be automatically rerouted, maintaining system integrity.

Currently, more than 280 cameras are installed around the Birmingham Digital Ring. The number of cameras that could be connected to the network is almost unlimited and future expansion of the Birmingham Digital Ring is likely to see this number rise to more than 700 inputs. As well as the currently provisioned 80 uncompressed video circuits, the AMG system also carries 40 data and audio circuits together with 10 Ethernet.

"This highly developed system gives us an exceptional resource in our traffic management strategy" comments Ian Harrison, senior traffic technology engineer for the Highways Agency.

"Enabling the PCO unrestricted access to live video streams from any of the more than 280 cameras gives a level of flexibility, insight and control that is crucial for traffic management around a major city like Birmingham. Our investment in one of the best surveillance and management systems possible will also benefit motorists."

The transmission stations at Coleshill and Ray Hall are each equipped with an engineer's position to allow maintenance functions to be carried out. Each is equipped with a control panel and a video monitor to which any camera can be routed to make fault finding quicker and easier. The data circuits are used for a number of purposes including the control of the fibre chassis themselves, matrix control, wind speed data collection, control panel highways (for the engineer's positions), V26 audio (camera control) and cross boundary data (TV Network Protocol).

Working through Tyco Integrated Systems (TIS), each motorway camera site was connected to the nearest transmission station on the digital ring. The cameras are presented to a video matrix and a battery of digital video recorders (DVRs) record and archive all of the feeds. This material may be retrieved and viewed by any control room operator at any control room over the system's Ethernet channels. It is also used by the HA's new intelligence unit to monitor and record traffic levels and analyse traffic patterns for future traffic planning. Each of the transmission stations can also exchange video and data with surrounding video surveillance networks. In this way, the impact of traffic incidents both on the Birmingham Box and the surrounding road network can be assessed. It would also be possible to incorporate information from these feeder routes into the Perry Barr PCO in the future.

The flexibility of the AMG system allows foreseeable future upgrades to be accommodated easily by reconfiguration of the system, without significant disruption. The capacity of the system can be increased by 100% without any disruption to the current network. Movement of the main control room or the creation of secondary control rooms can be done with ease. Linking in other parts of the national network for both incoming and outgoing signals allows for a nationwide management system.

Ian Harrison says "Using the fibre optic system we have been able to double the amount of CCTV motorway monitoring in the West Midlands without the need to install additional cabling. This has reduced the amount of equipment required and improved how we manage traffic if the motorway is closed or if an incident occurs"

"The resilient, self healing capabilities built in to the system are particularly relevant to round the clock surveillance operations in all spheres, not just road management. By choosing the Guardian 2800 series we did not have to sacrifice video quality. Unlike other video solutions, running on SDH or IP Networks, Guardian does not compress the video signal making high quality, real time video to every monitoring screen a reality."