Let it be said that fewer accidents happen in tunnels with bi-directional traffic than in tunnels with unidirectional traffic - that's according to an Austrian survey. But this study also states that if an accident does happen, this will be more severe than in a tunnel with unidirectional traffic. There is a 48 percent higher chance of dying in an accident in a single-tube tunnel than in a twin-tube tunnel. The severity of the accident results from the risk of a head-on collision. Humans are the weak link and inattention and incorrect action are the most frequent causes of accidents. Or cause of death. After all, in the Viamala tunnel in 2006, nine people died in smoke and fire because they simply could not get away from the scene of the accident in time. The Viamala tunnel, by the way, is only 742 metres long and this shows that even short tunnels have a risk potential that should not be underestimated.
In order to compensate for human error, it is particularly important to ensure high safety standards for tunnels - so that crashes can be avoided in the first place and self-rescue made possible when a disaster occurs. Single-tube tunnels without any escape or rescue routes are certainly critical. This risk increases with every increase in the number of vehicles, the share of HGVs, the length and gradient of the tunnel. The EU Directive from 2004 only requires a second tube for new tunnels with a traffic volume of 10,000 cars or more per day and lane. In the past, a second tube was often not built simply to save costs. This was why refurbishment has been well underway in recent years. At times, step by step: Following the disaster in 1999 in the Montblanc and Tauern tunnels, one of the first immediate measures to be introduced in the Katschberg tunnel was an independent air supply in the emergency phone booths which can hold up to four people. After this, remote-controlled vents were installed to extract smoke. These vents can be opened directly where the seat of the fire is located. This measure was introduced in the Tauern tunnel immediately after the disaster. In April of this year, the second tube of the Katschberg tunnel was completed and the second tube of the neighbouring Tauern tunnel is due to be completed in 2010. But it is not always possible to build another tube, sometimes for political reasons, as is the case with the St. Gotthard tunnel. At least safety galleries were chosen as an alternative. Thanks to the parallel safety gallery in the 17-kilometre long St. Gotthard tunnel, a fire in 2001 which broke out after a head-on collision did not claim even more lives than the eleven lost there.
One feature was very useful for the San Bernardino tunnel. When this tunnel was built, the fresh air duct was installed underneath the lane. And when the tunnel was finally refurbished, this fresh air gallery was transformed into an escape and rescue gallery. A new ventilation system was installed above the traffic lane area. The refurbishment, which took several years, gobbled up around 240 million Swiss francs, that's 80 million more than it cost to built the tunnel itself back in the 1960s.
The situation was completely different in the Arlberg tunnel. Here, cross-connections and a connecting tunnel were built between the 14-kilometre long road tunnel and the 10-kilometre long rail tunnel that runs parallel to it. By 2014, the rescue route distances are to be shortened even further. The escape routes each contain one assembly room designed to hold several hundred people. The construction costs of this project totalled around 47 million euro.
Up to now, eight million euro have gone into refurbishing the Wattkopf tunnel. After this tunnel was identified by EuroTAP in 2004 as Germany's most dangerous tunnel, funds were immediately approved. Although this tunnel did not give a completely convincing display this year - its rating was lowered due to a lack of emergency exits - a safety gallery is guaranteed for 2010. The ventilation system was generally revamped and this improves the possibilities for self rescue considerably. After all, when a fire breaks out, a smoke-free atmosphere is justifiable. In this case, demands on ventilation systems are higher in a tunnel with bi-directional traffic where cars are located on both sides of the fire which can additionally hinder access for rescue services. Overpressure must also be maintained in the escape routes of a tunnel system to prevent smoke from entering. A tunnel is a complex system of interaction and each tunnel must be individually adapted to meet the latest applicable safety requirements.
Around one third of the 282 tunnels tested up to now have bi-directional traffic, as do 18 of the 31 tunnels tested this year. Seven of these were given an overall rating of "good" and "very good", four were rated "acceptable", and seven "very poor". It must be said that all of the latter tunnels were found to have serious shortcomings in the categories of "Escape and rescue routes" and "Ventilation". All in all, over the past ten years, more than twice the number of tunnels with bi-directional traffic were given poorer ratings than tunnels with unidirectional traffic. On the other hand, the Pont Pla tunnel in Andorra, the winner of this year's test, along with some exemplary approaches to accident prevention, "escape and rescue" in other European tunnels and countries, are proof that not every tunnel with just one tube is automatically a dangerous tunnel.
EuroTAP - The Future of Tunnel Testing
Let it be said that fewer accidents happen in tunnels with bi-directional traffic than in tunnels with unidirectional traffic - that's according to an Austrian survey. But this study also states that if an accident does happen, this will be more severe than in a tunnel with unidirectional traffic. There is a 48 percent higher chance of dying in an accident in a single-tube tunnel than in a twin-tube tunnel. The severity of the accident results from the risk of a head-on collision. Humans are the weak link and inattention and incorrect action are the most frequent causes of accidents. Or cause of death. After all, in the Viamala tunnel in 2006, nine people died in smoke and fire because they simply could not get away from the scene of the accident in time. The Viamala tunnel, by the way, is only 742 metres long and this shows that even short tunnels have a risk potential that should not be underestimated.
One feature was very useful for the San Bernardino tunnel. When this tunnel was built, the fresh air duct was installed underneath the lane. And when the tunnel was finally refurbished, this fresh air gallery was transformed into an escape and rescue gallery. A new ventilation system was installed above the traffic lane area. The refurbishment, which took several years, gobbled up around 240 million Swiss francs, that's 80 million more than it cost to built the tunnel itself back in the 1960s.
Around one third of the 282 tunnels tested up to now have bi-directional traffic, as do 18 of the 31 tunnels tested this year. Seven of these were given an overall rating of "good" and "very good", four were rated "acceptable", and seven "very poor". It must be said that all of the latter tunnels were found to have serious shortcomings in the categories of "Escape and rescue routes" and "Ventilation". All in all, over the past ten years, more than twice the number of tunnels with bi-directional traffic were given poorer ratings than tunnels with unidirectional traffic. On the other hand, the Pont Pla tunnel in Andorra, the winner of this year's test, along with some exemplary approaches to accident prevention, "escape and rescue" in other European tunnels and countries, are proof that not every tunnel with just one tube is automatically a dangerous tunnel.
