Tunnels tend to be as safe, if not safer once a driver is in an past the ‘transition zone’ – an approximately 400m distance where the driver’s eyes are adjusting to the new light levels and visual stimuli. However, the approach to a tunnel and the first few hundred metres, as well as the tunnel exit tend to experience increased accident levels for a number of reasons.
The predominant incidents in tunnels and on the approach to tunnels are through changing lanes (side-swipe) and nose-to-tail. These are usually minor damage and minor impact, but if it’s a more serious crash, the implications can be exponentially worse, especially if a vehicle catches fire.
Why are tunnels more dangerous for drivers?
Driver behaviour in tunnels affects driver safety
Driver error causes almost all crashes and incidents in tunnels. Unlike the open road where there are pedestrians, cyclists and animals to contend with, tunnels are frequently single direction with only vehicles using them. Variations in driver behaviour are magnified in tunnels with particular problems being caused by drivers who are too aggressive and drivers who are too timid. Timid drivers cause traffic to slow down which feeds frustration in aggressive drivers.
On the approach to tunnels, drivers change lanes more than usual to try to guess the lane that will be travelling quickest; overtaken is frequently forbidden in the tunnel itself. This is where slower drivers should ensure they are already in the left-hand lanes well before the tunnel. Lane merging can be an issue just before tunnels.
In a single-direction tunnel, drivers tend to move away from the walls in the left and right lanes, meaning they are closer to vehicles in the centre lane(s), reducing the margin for error. This is especially noticeable for lorries which have an elevated accident risk in tunnels already.
Tunnel design affects driver safety
The design and inherent characteristics of tunnels play a part in increasing accident risk. It’s expensive to dig and maintain tunnels, therefore they are built to minimum requirements and this usually means that there are fewer runoff areas and the lanes are narrower. Motorists have fewer options for evading obstacles if there’s no hard shoulder which means it’s critical that drivers maintain a gap of at least two seconds to the vehicle in front.
Changes in light levels cause difficulties for drivers, especially older drivers whose eyes don’t react as quickly. If it’s raining, the change from dry to wet on the exit can cause problems.
How is tunnel safety improved?
- Using variable lighting in the tunnel to match the ambient lighting outside the tunnel
- Painting the walls a light colour
- Providing breakdown bays and hard shoulders within the tunnel
- Banning trucks either completely or at certain times
- Changing the exit and entrance orientation of the tunnel so that drivers don’t experience sun strike
- Variable message boards and signage informing drivers what to expect, but not within the first 400m when drivers are already overloaded by the new environment
- Gradients of less than 5 degrees
- Automated detection of incidents to ensure rapid emergency response
- Rumble strips between lanes and other markings to encourage safe speed
- Discouraging overtaking
How drivers can reduce their risk in tunnels
Drivers can maintain a gap to the vehicle in front of at least two seconds and keep a consistent speed to avoid bunching and jamitons. Sunglasses should be removed and headlights should be on. Drivers shouldn’t change lanes in the tunnel and should not enter a tunnel if they are running low on fuel.
Dealing with a vehicle incident in a tunnel
Check variable message boards (if available) as you approach the tunnel as they will warn of delays and lane blockages.
If your vehicle catches fire, attempt to drive it out of the tunnel, but don’t put yourself in danger. Put your hazard lights on and exit the vehicle as soon as you can. Don’t open the bonnet. If you have a fire extinguisher and it’s an engine fire, unlatch the bonnet (don’t open it), put the extinguisher nozzle through the gap and try to extinguish it. Get to an emergency exit.
If you have a collision with another vehicle, there’s no hard shoulder and your vehicles are driveable, exchange details then drive to the tunnel exit to sort the remaining details out rather than blocking the tunnel.
If you have a collision and your vehicle is not driveable, get it as far left as possible, put your hazard warning lights on, stay in the vehicle and call emergency services.
If traffic stops because of a tunnel accident ahead, put your air conditioning to recirculate, turn off your engine and turn on your radio to a local news station (you’ll need to keep the ignition on). There might be information boards that indicate the estimated wait time. They may also say if you need to evacuate.