The public comment period for a study about the impacts of building a light-rail Purple Line through the Maryland suburbs has been extended by 15 days and will now end Oct. 21, Maryland transit officials said Monday.

The comment period was initially scheduled to end Oct. 7. It is being extended due to requests from the community and others who wanted more time to review the technical and lengthy document, according to the Maryland Transit Administration.

The study details the potential environmental and community impacts of a proposed 16-mile transitway between Montgomery and Prince George’s counties. Those impacts include condemning 116 homes and businesses and building 20 electrical substations along the route, including several in residential areas.

Copies of the study are available at or at public libraries in both counties. The most detailed information about impacts to neighborhoods along the route is in chapters 2 and 4.

Map of the Purple Line route through Silver Spring and Langley Park. For light rail vehicles to work, power substations are necessary to convert electric power to appropriate voltage and type. The Purple line plan calls for 20 substations to be placed every mile along the route, including several in residential areas – some of the potential community impacts detailed in a recent state study. (Gene Thorp/The Washington Post)