Once the D2 Subway is in operation through downtown Dallas, riders will make their way down an elevator, escalator, or steps to reach the station below ground. Although it may not look like much, there is a lot that goes in to building a subterranean station that has the necessary spatial and safety requirements to accommodate a large amount of people.
Think of an underground station like a layer cake. There are multiple levels or steps to building a station below the surface; whereas, an above-ground light-rail station is simpler (much like a sheet cake is easier to assemble than its layered cousin).
Like a pastry chef following a recipe for assembling a layer cake, engineers must follow a detailed plan before diving into construction. For the D2 Subway to be a success, DART must undertake the delicate task of balancing the key elements of building a station: safety, space and access.
Safety is like the cake batter — absolutely essential. Elements that you do not need above-ground become imperative below-ground. Like we mentioned before, you have more layers to a subway station than a surface-level light-rail station.
For example, creating an effective ventilation system is necessary to maintain good air quality in the station, as well as to filter and remove any unhealthy air conditions associated with emergency situations like a fire. Ventilation and fire suppression systems are essential for keeping riders safe and will be a priority for the D2 Subway. Safety can also be enhanced through design. Keeping the platform open, visible and well-lit, as well as incorporating security and surveillance technology will be important to maintain a safe system.
Fitting everything underground can be a delicate task — like determining the perfect icing to cake ratio. DART must take extra precaution and plan differently when constructing stations underground due to limited space. Engineers often have to relocate utilities, pipes, and underground infrastructure to create enough space to build a station. Everything must be compressed as well as be supportive enough to house heavy machinery, equipment, and an electrical system below the surface.
Before getting to the cake you’ll often see decorations or candles on top — which is akin to the station access points, or pedestrian portals. Just like fitting the station itself underground, finding the right space and path for pedestrian access to the tunnel can be difficult, especially in a downtown area. Taking advantage of public right-of-way and linkages to nearby buildings or tunnels will be part of the process to defining these locations.
DART is a public transportation leader not just in North Texas, but a leader for the nation. We are committed to finding the most innovative and effective ways to plan and build the D2 Subway – including safe and effective stations. By effectively planning just how we will accomplish this engineering feat, we can build safe subway stations and make the D2 Subway a success for all of North Texas.