To power the Purple Line, Maryland will have to build power-converting substations along the 16-mile route. Transit planners plan to help the structures blend into existing neighborhoods by disguising them as single-family homes.


“Houses” like this one in Toronto could appear along the Purple Line. Photo from MTA.



According to a recent Washington Post article, the Purple Line will require multiple support structures and buildings, including 14 signal bungalows, or small buildings with radio and signal equipment, and a nine-story ventilation tower in Bethesda. There will also be 18 of what the Maryland Transit Administration calls traction power substations, which would feed power to the electrified rails.

Spaced at one mile intervals, these facilities house equipment to convert alternating current carried along high voltage transmission lines to the direct current used by trains. The buildings would be about 50 feet long and 14 feet wide.

Recently, people living along Wayne Avenue in Silver Spring got their first glimpses of the substations. Because they have the potential to introduce visual and noise impacts into quiet residential areas, some neighbors are concerned. In an interview with the Post, resident Anne Edwards described one substation proposed for the corner of Wayne and Cloverfield Road as an “industrial monstrosity.”

Because the Purple Line is a federally-funded transportation project, MTA was required to prepare an environmental impact statement. According to the document, which is open for comments until October 21, the line’s preferred alternative along Wayne Avenue is a highly sensitive visual corridor. The proposed substations would be visually intrusive, according to the MTA analysis, and the equipment housed in each is expected to emit “transformer hum” sounds.

MTA plans to mitigate the substations’ visual and noise impacts with insulation to prevent equipment noise from leaking out and by camouflaging the buildings to make them appear like single-family residences. According an MTA flyer on the substations posted at the Purple Line website, “The substations can be screened with fencing, landscaping and, as appropriate, the MTA will identify further measures to minimize their presence or make them blend in with the environment.”

Typical light rail substations are basic windowless boxes. They have all the architectural appeal of a cargo container or a construction trailer. That’s why the MTA will make Purple Line substations look like single-family homes instead.


A traction power substation in Minneapolis. Photo from MTA.


In an April email to a Silver Spring resident that was posted on various community listservs, Purple Line project manager Mike Madden noted that these substations can be found in residential neighborhoods around the US and the world. The MTA can design the buildings to “be more square in shape,” making them look more like houses, and give them landscaping and lawns in front, just like a normal house.


Possible Purple Line substation house. Photo from MTA.


The substation designs MTA distributed include a brick veneered building that looks a lot like the ranch houses or ramblers common in Montgomery County neighborhoods developed after World War II. Utilities and transportation companies around the world have used tricks like this for more than a century to minimize the visual impacts of unsightly infrastructure.

Photographers love engineering simulacra like the proposed Purple Line substations. Historic building facades conceal massive substations built to power New York City’s subways. Some of these were captured in Christopher Payne’s 2002 book, New York’s Forgotten Substations.

In 1987, Canadian photographer Robin Collyer began documenting transformer houses, also called “bungalow-style substations,” throughout Toronto. Each one was built “in a manner that mimics the style and character of the different neighborhoods,” Collyer wrote in 2006.

Closer to home, Pepco built transformer houses in residential neighborhoods in the Colonial Revival style popular at the time as early as the 1930’s. According to a 1954 Washington Post article on Pepco’s program, the company identified neighborhoods with increasing electricity demands and then went to work designing the faux homes. Pepco employees photographed existing homes surrounding the proposed sites, then a company architect designed compatible substation buildings.


Washington Post cartoon. “These Homes are Really Electrifying,” April 4, 1954.


Efforts to conceal infrastructure in the Washington metropolitan area weren’t limited to power substations. Today, telecommunications facilities disguised as pine trees, dubbed “monopines,” or as flagpoles and building bulkheads are found throughout the area and the nation. There’s even a monopine at Mount Vernon.


A “monopine” at the Montgomery County Trolley Museum. Photo by the author.


One of the earliest examples of concealed telecommunications infrastructure in Washington is the 1947 Western Union Telegraph Company microwave terminal in Tenleytown. Architects and engineers went through several designs to minimize the tower’s visual impact to the established neighborhood.

One design that included a clock mounted in the façade was discarded and the plain limestone clad tower that still looks out over 41st Street NW was completed with no apparent complaints from neighbors. The former Western Union tower was designated a District of Columbia historic landmark in 2003.


The Western Union Telegraph Company building in 2002. Photo by the author.


It’s far too soon to know whether the Purple Line’s faux home substations will inspire future generations of photographers or if at some point they may be considered historic. It is fair to say that once they are completed, they may be better neighbors than occupied “real” homes.

MTA will mow the lawns and keep the exteriors neat. Neighbors can rest assured that there won’t be any wild parties or competition for street parking. And it’s not likely that the new neighbor will be coming over asking to borrow a chainsaw or generator the next time a storm rolls through.