Road tunnel safety


EU law sets minimum safety requirements for tunnels, including measures to prevent them from becoming death traps in case of an accident. By 2019, more than 1300 km in the countries of the European Union of main road tunnels, will have been upgraded to meet the highest safety standards. On the Croatian territory, all structures, including tunnels, can be classified into 4 categories in terms of their vulnerability to fire and technological explosions. According to the regulation in Croatia, there are 2 tunnels in IIA, 3 tunnels in IIB and 6 tunnels are in IF risk category. For the total tunnel length of 50.693 m on highways there are 207 fire – fighters and 33 fire-fighting vehicles on disposal/available in the case of accidents what brings the cost of 4.900.000 EUR per year. Statistic for 2015. shows the number of 64 traffic accidents in tunnels and only 2 of them ended with seriously injured people. Croatia's Brinje tunnel has won at German auto club ADAC's safety test for the year 2007.

Tunnel Mala Kapela – the longest way

The longest tunnel in Croatia is Mala Kapela (‘Small Chapel’). It belongs to IIA risk category and due to positive result (+) on EuroTap testing in 2006., we will use it as example and give a brief overview of the operational plan for the protection and treatment in these conditions. The tunnel is geographically located between villages of Jezerane and Modruš and between Ogulin and Brinje motorway interchanges. The tunnel passes through the Mala Kapela mountain in the Northeast-Southwest direction. The first tunnel tube (5,78 km) through the Mala Kapela mountain was completed in 2005, and was used for both directions of traffic until the second tube (5,82km) was completed in 2009.


Fig.1 Tunnel Mala Kapela  

Fig.2 TSectional traffic control center Mala Kapela 

Due to the geotechnical characteristics of the rock mass, this tunnel falls in the middle category by weight construction. The total investment for the both tubes was more than a billion Croatian kunas. A contract for the construction was made between the concessionaire Croatian Motorwas Ltd. and the: Coopcostruttori Italia Viaduct dd Zagreb, Strabag AG Spittal, Hidroelektra engineering dd Zagreb, Konstruktor Engineering dd Split, Dalekovod dd Zagreb, Skladgradnja Ltd. Imotski.

Safety steps

The alert of the fire alarm in the tunnel Mala Kapela starts in the room for the control and management of the northern portal of the tunnel, which has a 24-hour duty with a minimum of two people.

There are 4 ways for the sign of alert in a case of an accident.

1.If a fire occurs in an area which is protected by a fire alarm system, audible and visual alarm will be activated. The duty operator must confirm the sound alarm with15 seconds, and the light alarm remains until the fire detection system resets. Monitor shows the exact address of fire detectors or the place for the lifting the fire extinguisher. After receiving the fire alarm, duty staff in the control room Mala Kapela notify the fire department to come to the spot and call an ambulance and traffic police. The duty operator over the speaker indicates people in the tunnel to evacuate the tunnel and to go to the second tube. If necessary, operator uses the radio system of tunnels. They inform the drivers and passengers to leave the vehicle and to go to the pedestrian passage in order to evacuate to the second tube where the traffic during that time has to be stopped.

2.Along the route of the highway telephone call bars were set. SOS cabins are placed in the tunnel with a call device that is used to establish contact with the emergency operator.

3.The system of video detection can detect the presence of smoke using cameras mounted in the tunnel, based on which the video wall activates layer video systems sound and light signs warns the operator on duty at the abnormal condition in the tunnel.

4.The system of the remote management and control measures the visibility and concentration of CO in the tunnel tube during: a large reduction of visibility in the tunnel and a large increase of the concentration of CO.

In 2015 there was only one accident recorded with fire and without injured people. Fire station of the Mala Kapela has 28 employees and is equipped with 5 vehicles and covers a section with a length of 71 km from Bosiljevo to Žuta Lokva – Otočac. Due to the mismatch of Mala Kapela with the provisions on minimum safety requirements for tunnels, the deadline for the planned activities is December 2018. The plan is to spend further serious amount as improvement in tunneling. These activities include for example better traffic signs, reconstruction of the automatic system of tunnel closure, upgrade of the communication and monitoring systems etc.

Sources: HAC

author: Matea Uhlik Vidović, 07.06.2016