Smoke extract and ventilation specialist Senior Hargreaves has completed two technically challenging contracts, with a value exceeding GB pound 8 million, at St Pancras International station and at the tunnels on the High Speed 1 (HS1) rail link.
At the recently opened St Pancras International station, the European platforms are separated from the domestic services and have the same security, immigration, passport control and customers facilities as any major port or airport. Space limitations meant that many of the train-side facilities had to be installed below the platform level. Fortunately, the Victorian engineers left large voids beneath the platforms, which originally housed a beer vault and is now where security and customs offices, shops and other facilities are located.
To ventilate these below-platform areas for daily comfort and emergency smoke removal, Senior Hargreaves installed a network of above-ceiling ductwork, which is connected by vertical ducts to the main extract ducts located in voids under the floor. HFD/SID fire ductwork was used in many areas in this network. In a fire situation it enables smoke and hot gasses to be transported safely out of the building, without fume leakage or premature collapse, increasing the window of time for the emergency services to organise safe evacuation.
A radically different approach was required in the three double bore tunnels on HS1. The two deep tunnels are ventilated by vertical shafts, which house heavy duty, fire resistant ductwork with temperature resistant, powerful high volume reversible fans. These shafts can be used to inject fresh air into the tunnels or extract stale air. If there is a fire or other incident, the shafts can be used to extract smoke or fumes close to the source. Alternatively, they can introduce fresh air remotely to give airflow or pressurisation to protect passenger escape routes, and give safer access for fire and other emergency services.
In tunnels that run under the Thames, where the installation of shafts was impractical, a system of injectors has been installed at each tunnel entrance. These introduce air at high velocity via a slot in the roof of the tunnel, known as a Saccardo nozzle. As with the deep tunnels, the principle is that in an emergency the adjoining tunnel, which is cross linked by a series of protected passages, will become the escape route, and fans are used to give pressurisation to exclude smoke and fume from this area.
