Cuijk-based Colt International develops tunnel technical installations to ensure fire safety Delft Station

Royal VolkerWessels starts completion of second phase Delft Station

Vialis B.V. and Van Hattum en Blankenvoort B.V., both part of Royal VolkerWessels, are realizing the completion and tunnel technical installations of the Tunnel Delft, the second phase of the NS railway station in Delft. In 2025, the Delft Tunnel will open in its entirety (phases 1 and 2) for train traffic between The Hague and Rotterdam. Safety of passengers at Delft station is paramount. Especially if a fire should break out. For fire safety in the tunnels and the station, Colt International from Cuijk is heavily involved in the realization of the smoke control system in the station, ventilation system in the tunnels and the overpressure systems of the emergency stairwells.

The approach to the Hague-Rotterdam rail route is part of the High-Frequency Rail Transport Program (PHS) through which ProRail is gradually making the busiest rail routes in the Netherlands suitable for more train traffic. By doubling the track between Rijswijk and Delft Zuid, and modifications to infrastructure and safety between Delft Zuid and Rotterdam will allow eight intercity trains and six sprinters to run every hour in each direction on this route by 2025. This will allow passengers to take trains between Rotterdam and The Hague every five minutes. In 2015, the first tunnels with tracks 1 and 2 were commissioned. In mid-2019, the completion and tunnel technical installations of the third and fourth tunnels began. VolkerWessels is also continuing to build the underground platform, which lies between the four tunnels. This second phase of the project will be completed by the end of 2024 for high-frequency train traffic. It is estimated that approximately 40,000 passengers will then board and alight in Delft on an average weekday.

Stan Veldpaus is a project consultant for fire safety at Colt International in Cuijk, a manufacturer of smoke control systems, climate control systems and solar shading systems. One of Colt's specialties is the development of smoke control systems such as Smoke and Heat Evacuation Systems (RWA), overpressure systems and back pressure ventilation systems, for both above and underground buildings and tunnels. For the Delft tunnel, Colt developed the smoke control systems for both the station, tunnels as well as the emergency stairwells and will maintain them entirely after completion. "The realization of the ventilation in the four tunnels and the station is quite complex, because the whole thing is in open communication with each other and has to act together. The ventilation systems must work together in such a way that in the event of any fire, both the station, including the platforms, and the tunnels are kept sufficiently smoke-free," says Veldpaus. "This requires thrust ventilators in the tunnels and mechanical fire gas ventilators in the station. The whole thing should ventilate the smoke and heat as well as possible," Veldpaus explained.

For both phases, for the aforementioned systems, plant design with CFD models (computational fluid dynamics) has been optimized. "The computer simulations were produced by flow modeling experts within Colt itself," says Veldpaus. "The simulations predict what effect air currents will have in a tunnel and the station if a fire breaks out. So the computer indicates the effect of airflow on visibility and heat development." In a fire, smoke and heat must be dissipated quickly. The removal of smoke and heat is thus provided by the RWA system of the platforms, the central hall and the thrust fans in the tunnels. This leaves sufficient visibility for passengers and staff to escape quickly and safely. The systems also ensure that firefighters can quickly locate and extinguish fires. These systems thus control the greatest danger immediately after a fire breaks out, giving passengers and staff significantly more time to escape," Veldpaus said.

Colt also provides the overpressure systems in the emergency stairwells located adjacent to the tunnels. By creating a large airflow from the stairs to the tunnel, no smoke will flow into the stairwell. Furthermore, the pressure difference when the door is closed will also prevent smoke from entering the stairwell. Due to the different designs of the stairwells present, different types of positive pressure systems occur in this project. Per stairwell the overpressure system was designed, installed and tested.

The Royal VolkerWessels companies Vialis and Van Hattum and Blankevoort are responsible for the execution of the tunnel technical installations and completion of the second phase of Delft station. As in the first phase, Colt's smoke and heat control systems will also be installed in the second phase. Marcel van Stek is project buyer at Vialis and involved in the tunnel technical installations. Besides installing the ventilation, Vialis as system integrator must also ensure that the fire safety systems and installations are linked together. "Vialis will install 19 thrust ventilators each in tunnels 3 and 4. In tunnel 1 and 2 there are 38 identical fans. Eventually, all 76 thrust ventilators in the four tunnels will be linked together, which in turn will be connected to the RWA systems on the platforms and in the central hall," says van Stek. These systems suck in air and push air in one direction with a certain force. The number of thrust fans depends on the geometry of the tunnel. "This force is such that when smoke and heat develop, air is pushed up one side of a tunnel, out along with it in the direction of travel. This prevents smoke and heat from reaching the platforms and central areas," he explains. The four emergency stairwells leading from the tunnels to ground level are equipped with standalone positive pressure systems. "Tunnel 3 and 4 will also have four additional emergency stairwells, in which Vialis will install the same Colt standalone pressure relief systems," he says. "These standalone overpressure systems hold back smoke and heat in the stairwells and blow it back into the tunnel. The installations ensure that passengers can get out of the tunnels as quickly as possible in the event of an emergency," says van Stek.

Fire ventilation is one of the most important aspects at the Delft Tunnel. "It is a big plus that Colt also designed and supplied the tunnel technical installations in the first phase," says van Stek. With the technical information and data from the computer simulations, Colt worked out and optimized the smoke control and Smoke and Heat Evacuation systems with extreme precision. "Intensive involvement and solution orientation shown are testimony to a strong and reliable chain partner in complex projects such as the Delft Tunnel," indicates van Stek.