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The Spaarndammertunnel in Amsterdam is prepared for calamities such as fire. For this purpose, the tunnel is equipped with, among other things, an overpressure system and longitudinal ventilation. In order to safeguard the Spaarndammertunnel and the escape routes from smoke and heat in case of a calamity, Colt International BV in Katwijk (NB) provided the engineering, delivery and assembly of the overpressure system in the middle tunnel canal and the barrage ventilation in the tunnel tubes. These help ensure that the Spaarndammertunnel is prepared for calamities such as fire.
Stan Veldpaus, project consultant Smoke Management Systems at Colt: "If you find yourself in a tunnel on fire, you need to be able to find a safe refuge quickly. That's why every tunnel has an escape channel. Putting this on overpressure keeps smoke and fire out. At the Spaarndammertunnel, where the escape channel lies between the two tunnel tubes, we supplied the overpressure installation for this."
If necessary, the positive pressure in this tunnel is scaled up to the maximum flow rate. Since smoke blown out through the tunnel ventilation system can be drawn in through the supply fans of the overpressure system, both sides are equipped with 2 overpressure fans (redundancy). Only the fans at the entrance of the tunnel loaded with fire are switched on. It must also be taken into account that the door of the escape passage, which turns inward, can be opened safely. Therefore, sensors continuously measure the air pressure. In addition to the overpressure system, Colt supplied and installed the thrust vents in the tunnels, as well as the sensors and the decentralized switchbox overpressure system in the escape corridor.
Thrust fans at the tunnel entrance.
One way to fight the fire is to direct strong air movement in one direction (longitudinal ventilation). This prevents backlaying that can occur due to the low tunnel height. Smoke and heat rise, hit the tunnel ceiling and can then spread in either direction. However, by pushing air along with the direction of travel on one side, smoke and heat are blown toward the exit, the front remains smoke-free, and the extinguishing work can take place with the wind at its back. Veldpaus: "Longitudinal ventilation was also used here. To provide both tunnel sections with it, we supplied 8 thrust blowers for each tunnel tube and fixed them in the ceiling, 4 at the entrance and 4 a little further into the tunnel. These thrust fans can withstand hot air of 250 degrees Celsius for at least 1 hour." They are also designed to blow away exhaust fumes. To reduce their noise, Colt installed silencers on both sides of the fan motors.
"The profile-free space was important in determining the dimensions of the fans," says Veldpaus. "The larger their diameter, the more power. Here you are always bound by the cross section of the tunnel. Since there is not that much space, we installed steel fans with a diameter of 1.12 m, a total of eight 1125 N thrusters 3.5 m long. The supply fans in the escape corridor each have a diameter of 900 mm and a length of 750 mm."
Colt specializes in developing climatic systems for an environment in which air quality, (day) light and safety are guaranteed. The international company's activities include fire protection and smoke control in infrastructure projects, from design to annual maintenance and certification. Here Colt works for the business community such as construction consortiums, but also for end users such as the Department of Public Works.
