Unforeseen emergencies can occur at any underground job site. Whether it’s a fire, gas leak, or some other hazardous situation, construction workers on underground projects face an entire set of unique working conditions. The work is dangerous and unpredictable, and if a threatening situation arises, the last thing workers want to face is egress difficulty.
The potential for danger is elevated in an extended project, such as the construction of a new 8.5-mile rail line currently being built in Los Angeles. The $1.766 billion line will have eight stations, and the line will include underground and aerial sections, along with some at-grade. Construction began in 2014 and is expected to be operational by 2019.
One of the challenges for architects was establishing code-compliant egress for underground workers, and eventually, subway riders. The construction team building the project, Walsh/Shea Corridor Constructors, installed six emergency hatches at three underground stations along the rail line and four transit system emergency evacuation doors at above-ground stations.
“Walsh/Shea made these doors an important part of the project at the very beginning,’’ said Dave Pebley of Specialty Building Components, who was contacted by the Los Angeles County Metro Rail System six years ago, when the extension was first announced. “Even before there were any designs, they knew that they wanted a floor door that they wouldn’t have any problems with. It had to meet code requirements, but it also had to meet demands of the job. These doors are located on the sidewalk, and they had to be tested by the fire department. It had to meet H-20 loading specifications, but also be light enough that it can be opened with a 30-pound push.”
A H-20 rating refers to the ability of a roadway or safety component to safely accommodate 3-4 axle vehicles, such as a large semi-truck and trailer, or fire engine. The code also requires that the door must also be opened with a push of 30 pounds or less. “To make a door like that, it must be extremely well-designed and engineered,’’ Pebley said. “There are very few doors that meet those requirements.”
Pebley recommended doors manufactured by The BILCO Company of Connecticut, a long-time supplier of emergency egress products for the construction industry. The doors feature a panic bar locking mechanism and, despite their large size, can be operated with one hand. The large double-leaf hatches are reinforced for 900 psf and supplied with cover coatings that prevent slippage in wet conditions.
“Underground workers love these doors because they know if there’s an emergency, they can get out quickly,’’ Pebley said. “Plus, they don’t want back injuries. They are sprung very carefully, so it’s not going to fly open, but it’s also relatively easy to open. It’s very well-engineered and constructed. It has been used in a lot of transit applications such as this one.”
Pebley said workers encountered design challenges throughout the installation. The most problematic was customization—architects and engineers returned to him eight times with re-submittals. One particularly challenging door stood 18 inches wide on one side and 42 inches wide on the other.
“There were a lot of design challenges,’’ Pebley said. “They not only had to meet the egress code requirements, but they had to be built to the right dimensions. We did a lot of work to change the width or an angle to get them to work correctly.”
Architects designed the project with the exact number of doors needed to keep utility workers safe. In the event of an emergency, every second is precious.
“It’s important for utility workers to know when the emergency arises, the door will work properly,’’ Pebley said. “You don’t want to get to the top of the stairway and the door won’t open. You don’t want the door to pop open and hurt somebody above ground, either.”
The doors used in the project are made with Type 316 stainless steel hardware and include an automatic hold-open arm lock to ensure safe egress. The heavy-duty construction and positive latching mechanism help prevent unauthorized access. The doors also include a 25-year warranty. BILCO also manufactures grating systems and ladder assemblies that help underground utility workers move quickly to safety.
“You want doors that are safe for a worker to use,’’ Pebley said. “You don’t want to have a problem with the door when there’s an emergency. You know they’re going to work, and you know they’re going to last. That’s important for any underground utility worker.”
When completed, the rail line will be an important part of the Los Angeles infrastructure. The line will add a key corridor to the LA Metro’s growing transit network. Eventually, the line will connect the Crenshaw Neighborhood and Leimert Park to the City of Inglewood and Los Angeles International Airport.
The project was planned after the Los Angeles riots in 1992 to better serve transit-dependent residents in the corridor and provide an economic stimulus to the region. Reports last fall said development was booming along the corridor, and real estate prices were rising around many of the stops.
“This is a project that is important for Los Angeles,’’ Pebley said. “We’ve been working with the Metro since its first station was built in downtown Los Angeles 25 or 30 years ago. We have doors on those stations that are still operating beautifully.”
The new transit line is also expected to bring commercial and retail development and help ease congestion on the region’s jammed roads. The project did not seek state or federal money, and is being funded with sales tax revenues and local sources. “Measure R,” the half-cent sales tax approved by Los Angeles County voters that is providing the bulk of the funding, was passed in 2008. UP