Tunnel | Safety
Tunnel safety will become even more important in the future as cars will be propelled by gas (LPG), light metal accumulators, hydrogen and terrorism. The risk of electrical sparks in the case of collisions will increase. Since 1995 OrbiPark has been active in tunnel safety in fields including: tunnel firefighting concepts, fireproof tunnel building, fire mode ventilation, safer lighting of tunnels, safer and cheaper fire detection.
The fog nozzle is specially designed for firefighting in tunnels and covers 360 degrees. Unlike other nozzles, it does not rotate water, but instead splits a water film. The nozzle has a self-cleaning function with a flow of 250-500 liters per minute. Its construction makes it possible to add accessories, such as BONPET, used in the second phase of firefighting. The fog foot print spray area of one nozzle is 20m x 30m.
A test tunnel, built by EKOVENT in Krapina (CRO), represents a historic milestone in tunnel fire safety and a new concept of fire mode ventilation.
Measurements in the tunnel have confirmed that, for the first time in history, using 3K ventilation and operating in fire mode, a secure withdrawal and intervention in fires up to several hundred MW (several full load trucks) can be provided. The 3K ventilation system uses less energy than conventional ventilation systems when operating in standard mode. In the case of a fire the entire outer side of the tunnel – the 50-100m fire zone – is smoke and damage free
Discreet lighting of tunnels is dangerous for older drivers. This problem will escalate in coming years as, instead of older high pressure sodium light bulbs, more cold white lights, such as metal halogen and white blue specter LED, are installed.
This phenomenon can be explained by the physical law of (light) refraction. Cold white light from a point source refracts much more in our eyes than yellow light.
In most tunnels light sources are exposed which, among older drivers, cause a dangerous glittering effect. Over time, after the age of 30, lenses in our eyes become more yellowish.
Older drivers see a corona glare ring around every white light source, which is similar to looking at a full moon on a slightly foggy night.
Our perception recognises light surfaces as bigger and simultaneously closes the pupil. This results in less light, a smaller spectrum of shades, poor recognition – especially dark edges of roads, thus making driving more difficult and his driving dangerous for all.
Light sources in tunnels should be shaded to 45 degrees and yellow light sources should become standard in tunnels.
Europe has established minimum requirements for safety in tunnels through the 2004/54/EN Directive of the European Parliament and of the Council of the Commission dated 29.04.2004. However, the regulation is still subject to national rules which are adapted to local traditions.
There are several lessons learned and good practices used that are not adopted by local tunnel operators which hide behind obsolete national standards.
Strong winds (up to 180km/h) cause serious problems in some tunnels. High air flow dramatically increases the chimney effect in a tunnel and thus increases fire danger. Tunnels, such as Kastelec in Slovenia, where a portal was cut into a stone slope, actually present a ‘Venturi tube’ effect and collect even more wind. Ventilation fans blowing against strong wind use a lot of energy and are not particularly efficient. This can therefore result in such tunnels being closed for several days per year. Simple aerodynamically shaped arches, as a prolongation at the entrance of the tunnel, would reduce air speed, just like a silencer mounted on a pistol.
Raised pavements in tunnels are a thing of the past, expensive relics that should by no means be installed in tunnels. In the case of evacuation from a smoked dark area, a raised pavement with mounted directional lights becomes an obstacle.
In the case of collision, touch-with a sharp edge, tyres may be shredded, disabling control of a vehicles, as was demonstrated, tragically, in a Swiss tunnel where a Belgian bus, carrying children, was involved in an accident. Tunnels without a raised pavement exist in Italy where, if such an accident were to occur, the bus would only scratch the wall and would not bounce without control into the tunnel niche.
The principle of longitudinal ventilation is still used in tunnels. It should only be used in jet engines and cement rotary kilns and could be best described as “more air – more fire”. 3K reversible ventilation enables escape to both portals, extracts four times more smoke, and does not blow fresh air (like bellows into a smelting furnace) into a fire, as do existing 2K ventilation systems.
Green “escape” direction lights are mounted on the right-hand wall of single directional twin-tube tunnels, which is potentially misleading and dangerous. Crossing passages are always between lanes – that is on the left side of the tunnel. Nevertheless, regulations demand installation on the right wall of the tunnel tube. The shortest way is not always the safest way.
Vehicles stopping suddenly in front of a tunnel can be life-threatening.
Tests have confirmed that it is not uncommon for tens, or even hundreds, of vehicles to overlook a red traffic light in front of a tunnel. The reason for this problem is the small illuminated area of traffic lights, which are designed for slow urban driving and are not suitable for high speeds on motorways. Horizontal installation of traffic lights is also not suitable for colour-blind drivers. A better solution is indication with a red X, or even SoftStop projection of a traffic stop sign on a water screen on the entrance to the tunnel.
Installation of signalisation only on the portal is not sufficient, additional signalisation must also be within a reasonable distance in front of the tunnel, similar to the regulations at railway crossings.
In some tunnels no signalisation for stopping traffic is installed. Some tunnels use reflecting parts to mark the tunnel entrance, which helps orientation in poor lighting conditions.
The EU should harmonise security markings in tunnels, taking into consideration existing good practice.
Loudspeakers are strictly forbidden in Swiss tunnels, while in the rest of Europe, however, one extra point is awarded for loudspeakers by the TAP ADAC test, and so, for that reason, they are installed by all national operators.
The fact is that the sounds physically bounce off tunnel walls and thereby strengthen, as happens in a trumpet or in the horn of an old turntable. Due to longitudinal echo, words become incomprehensible, because sound travels slower than electricity in wires. Expensive electronics, which control the audio delay, is not a solution. Regardless of implementation: traffic; ventilation and panic generate sounds that multiply with echoes. The third problem is that generalised commands such as “Leave the tunnel!” or “Turn left!” may be misleading in a panic and misunderstood due to different positions of people in the tunnel.
In a longer tunnel there can be a large number of people of different nationalities and with different language skills; some would not understand a word, even if they heard it. All communication must be carried out exclusively by optical signs that would be universally understood.
At a time when there`s at least one wireless phone in each vehicle, it`s completely pointless, just to meet the regulations to install phone booths in tunnels and, in case of fire, to ask mothers to leave the vehicle with children in it and run through the smoky tunnel for several hundred meters to the phone booth.
is obligatory fire safety equipment in tunnels. Not many people know that plain water can in fact increase car fire if no additives are used.
Only hydrants with special foam additive mixer are safe to use and have sufficient extinguishing effect but such hydrants are installed only in some countries and even there not in all tunnels.
Therefore plain water hydrants are usually simply locked for professional use only. Not to protect people from steam explosions, but mainly to prevent theft of hand extinguishers from the hydrant cabinet.
As a driver I am obligated to help and extinguish starting fire. But how? With my bare hands?
Concrete fire protection
Lack of knowledge and following old practices prevents implementation of new inventions. For example: addition of polypropylene fibers into concrete of the tunnel tube (extremely cheap additive) which significantly prolongs concrete fire resistance is prohibited everywhere, except in the Netherlands, where this technology was invented.
The biggest problem for implementation of new safety technologies is corruption and old practice/routine. When a single company becomes the exclusive supplier certain relationships are established, special three times overvalued equipment is installed, because nobody wants to be poking around in safety equipment that is covered with certificates and required by national regulations.