A common refrain heard in transportation circles is that while there is broad consensus that U.S. infrastructure requires major investment, a commensurate dedication to funding projects often fails to materialize. But a major exception is taking shape in the Maryland suburbs of Washington, D.C. where the Purple Line promises to transform the corridor it will connect.
The Purple Line will operate as the D.C. area’s first circumferential rail transit line and will connect to a variety of other public transportation systems, including all three MARC commuter rail lines, Amtrak’s Northeast Corridor, the Washington Metropolitan Area Transit Authority’s Metrorail Red, Green and Orange Lines and a host of local bus services. Featuring 21 stations along its 16.2-mile corridor, the Purple Line will link lower-income communities as well as the University of Maryland with job opportunities and other pursuits, while simultaneously serving as the spine upon which a real-estate renaissance is poised to occur.
Worth the Wait
The Purple Line’s roots go back to the early 1980's. After abandoning its Georgetown Branch line in 1983, CSX sold the track right of way to Montgomery County in 1988. It was not until 2002, however, that the Maryland Transit Administration (MTA) began studying a range of alignments and different transit modes (light rail and bus rapid transit).
In June 2016, the overall $5.6 billion Purple Line project had its financial close, arranged through an innovative public-private partnership (P3) between the Maryland Department of Transportation/MTA and PLTP. The Purple Line currently is the largest transit P3 project in the U.S.
With funding in place and a Record of Decision (ROD) from the Federal Transit Administration, the Purple Line was primed to start construction in 2016. However, the ROD was vacated in August of that year, when project opponents filed a legal challenge that questioned ridership projections and the impact on adjacent transit systems. Following approximately a year of litigation, a federal appellate court dismissed the plaintiffs’ objections and the ROD was reinstated.
The Purple Line is projected to carry just under 70,000 daily riders by 2030, a significant portion of whom will be former drivers of single-occupant vehicles. The Purple Line is forecasted to remove almost 16,000 daily vehicle trips from local highways. Future transit travel times are anticipated to be approximately 40 percent faster than they would be if the Purple Line is not built.
Neighborhoods that the Purple Line will travel through already are benefitting from the light rail project. Craig said, “Investment along the Purple Line is already at $2.5 to $3 billion, and it's coming in anticipation of the line’s opening. It easily could be much greater in 20 years.”
According to Ken Prince, who serves as Construction Manager/Deputy Project Manager for Purple Line Transit Constructors, the design and construction arm of PLTP, “The job is challenging from an engineering standpoint and operating in an urban area requires enormous coordination with a wide variety of constituencies.”
“A great deal of planning has gone into minimizing disruption to existing services, coordinating with adjacent property owners and rail systems, and recognizing this is a heavy corridor with existing utilities that are known and unknown,” said Prince. “When working in an area of dense population, safety is an even greater concern,” added Craig.
The Tunneling Method
This spring, construction has focused on the tunnel element that will be cut utilizing the Sequential Excavation Method (SEM). This tunneling method was selected due to the short length of the tunnel and because it allows immediate adjustment of the sequence of excavation and ground support systems in response to conditions that are encountered in the field. The area being tunneled has weak rock in the near the surface that can be excavated with a large excavator and a more resistant lower portion that will require drilling and blasting.
“We're utilizing the most current machine control and 3-D system to maintain vertical and horizontal alignment. With 50 to 75,000 residents and businesses along the entire alignment, we have a noise commitment that we're monitoring in real time to ensure we remain within county limits,” said Prince.
While the Purple Line’s light rail vehicles are designed by a Spanish company, CAF, they are being assembled in Elmira, New York. At 140 feet, they will be the longest light rail vehicles in the U.S., and each car features five individual segments that are articulated to navigate turns. The trains have a maximum capacity of 431 passengers and will be equipped with 80 seats. “They're unique in the way they're articulated and in their drive system,” says Craig.
Working in the vicinity of rivers and streams that spill into the Chesapeake Bay brings an additional layer of challenges. “There are highly stringent environmental protections we must adhere to,” said Craig. “We have to be aware and careful when it comes to spill and erosion control, ensuring no sediment gets into the surface water.”
Constructing a project as mammoth as the Purple Line in an urban environment involves major interaction with a large number of outside players. These include CSX Transportation, Washington Metropolitan Area Transit Authority, Montgomery and Prince George's counties, the Maryland-National Capital Park and Planning Commission, University of Maryland, Maryland State Highway Administration, Verizon, Pepco, Washington Suburban Sanitation Commission. and local municipalities in the project area. There also are a myriad of contractors and subcontractors. The responsibility of keeping everyone on the same page in terms of scope, design and construction falls to Jeff Ensor, who also serves as MTA’s Transit Development and Delivery Chief of Staff Director and Director of Project Delivery and Finance.
Following years of study and legal challenge, the Purple Line is picking up speed and scheduled to deliver its first passengers in late 2022. The Purple Line will transformation the corridor that and promises major economic benefits and a better quality of life for area residents making it an infrastructure project everyone can support.
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