When the Metropolitan Transit Authority of Harris County celebrated the opening of its new North Line on December 21, 2013, it decorated the first train into the station as a present from Santa to the city. © Metropolitan Transit Authority of Harris County
The city is more than tripling its light-rail system, concurrently building three new lines to connect business centers with residential neighborhoods.
February 4, 2014—The Metropolitan Transit Authority of Harris County (METRO), which serves Houston and the surrounding areas, is in the midst of an ambitious expansion program that more than triples the number of miles covered by the original 7.5 mi Main Street (Red) Line of the city’s light-rail system, connecting residential neighborhoods with several key commercial districts in the city.
The expansions build on the success of the Red Line, which opened days before the city hosted Super Bowl XXXVIII at Reliant Stadium in 2004. The line connects Reliant Park and the Texas Medical Center campus with downtown Houston and the Theater District.
“It has been a tremendously successful line,” says David Couch, the vice president for rail construction with METRO. He notes that with 40,000 boardings per day, the system is one of the busiest per mile served in the nation. “It provides a good core.”
From this core the city is undertaking three expansions that began simultaneously. The first, the North Line, is a 5.2 mi extension of the Red Line, going northwest from downtown into some key residential neighborhoods. The $756-million extension includes eight stations, the last of which will be the only aerial station on the system.
The second line under construction is the Southeast (Purple) Line. The $822-million, 6.3 mi extension begins downtown, links with the Red Line, extends south to the campus of the University of Houston, and then extends southeast into residential neighborhoods, stopping at 10 stations.
The third expansion, the East End (Green) Line, follows the same path as the Purple Line through downtown before splitting off to follow a 3.3 mi route farther to the north, into the city’s eastern residential neighborhoods. The line has five unique stations.
Trains run at grade on city streets in dedicated lanes that are segregated from traffic via a series of raised cylinders, 4 in. high and 1 ft in diameter. The rolling stock is Siemens S70 light-rail vehicles, powered by a 750-volt overhead catenary. The control system communicates with the city’s traffic signals, the light-rail getting priority at intersections.
The projects have a single designer/build contractor—HRT (Houston Rapid Transit). HRT is a joint venture comprising Parsons’ transportation group, of Pasadena, California; Granite Construction Company, of Watsonville, California; Kiewit Texas Construction L.P., based in Irving, Texas; and Stacy and Witbeck, Inc., of Alameda, California. Couch explains that constructing three simultaneous expansion projects concurrently presented METRO with several benefits.
“By having everything under one design/builder, with them putting the same system and the same components in for all three of the lines, it gives you an economy from a financial standpoint and it also helps you from a standpoint of not having to integrate disparate systems. It works very well,” Couch says.
Another benefit of concurrent construction is it speeds the process of creating a grid of transit lines to link the city, which is unusual in that there isn’t a central business core surrounded by rings of suburbs, Couch explains.
“Houston is a little bit different than a lot of other cities,” Couch says. “There are a series of business centers. They are separated and there is a lot of residential in between [them]. By putting the light-rail in, [we] connect those different centers.”
Couch says the biggest engineering challenges were preparing the foundations for the guideway in a complex inner city where portions of the infrastructure date back to the late 1800s. The guideway foundation requires excavation that is 2 ft wider than the track width and 4 ft deep.
“Anytime you’re in an old inner city, the real “as-builts” are always interesting,” Couch says of the network of utilities infrastructure. “You get the challenges of what you have to do to relocate many of those lines while maintaining service.”
To maintain utility service, traffic patterns, and access to businesses and residences, the team developed a phased approach. Phase one is excavation and relocation of the utilities. Phase two is the replacement of the sidewalks and roadways. Phase three is the installation of the guideway and tracks. The final phase is the construction of the stations and installation of the catenary and control systems.
There are two station configurations, both of which are 200 ft long. A central station services both directions from one platform that is 22 ft wide with a 100 ft gullwing steel canopy in the center; glass roof panels and a glass windscreen divider admit light. At locations at which that configuration is not possible, there are separate, narrower platforms on either side of the guideway.
To capture the essence of the residential areas into which the lines extend, METRO commissioned local artists to create murals that were incorporated between the glass panels of the windscreens.
The North Line was completed in December and opened to a warm public reception, Couch says. “We had the opening on the 21st. We actually wrapped one of our vehicles to make it look like a Christmas present. And we had a big opening. It has been extremely well received. Everything has been very positive.”
The Purple and Green lines are slated for completion later this year.