NATIONAL Highways has given an exclusive peek into an emergency exercise carried out in a tunnel on the A27.

The drill, codenamed Exercise Higgins, was carried out at the Southwick Tunnel and involved a road traffic accident and an electric vehicle fire.

More than 100 people were involved in the emergency exercise, with West Sussex Fire and Rescue, East Sussex Fire and Rescue, the local authorities and the Environment Agency also taking part.

Firefighters were seen tackling a “car fire” in the tunnel as smoke poured from the bonnet.

The Argus: Fire crews tackled a 'blaze' in the tunnel during the exerciseFire crews tackled a 'blaze' in the tunnel during the exercise (Image: National Highways)

John Nicholas, Southwick Tunnel manager at National Highways, said: “The A27 Southwick Tunnel live exercise is one of many opportunities that National Highways takes to work with local emergency services, local authorities and stakeholders to test, validate and train in a controlled environment on the strategic road network.

“The planning and preparation for these events takes many hours of dedication from each participating organisation which leads to improvements in training, refinements in procedures, reprioritisation of investment works with better working knowledge and stronger working relationships for all involved.”

All agencies tested their individual and joint operational procedures, operations and life safety systems, as well as other elements such as smoke detectors, alarms, fire, evacuation and sprinkler systems, both on-site and remotely.

The Argus: 'Smoke' was seen pouring out of one of the vehicles in the tunnel during the exercise'Smoke' was seen pouring out of one of the vehicles in the tunnel during the exercise (Image: National Highways)

The Southwick Tunnel is a 490-meter twin-bore road, which opened in early 1996 as a part of the A27 Brighton bypass.

The tunnel has long been subject to speculation that it is the entrance to a secret military bunker.