Maryland residents who want to see whether they might lose their home or part of a yard if the Capital Beltway or Interstate 270 is widened to accommodate new toll lanes can type their address into an online mapping tool that shows details of the traffic relief plan’s potential effects.

The Maryland State Highway Administration’s interactive map — click here — shows the outlines of both highways’ current rights of way, as well as lines showing how much they would need to expand to accommodate different toll lane options under consideration. The lines are in different colors for each of the six options retained for further analysis. (The seventh option — not building anything — is automatically included in such federally required studies.)

The Maryland State Highway Administration has cautioned that the maps are “very preliminary” and show worst-case scenarios because the companies that will design the lanes will be rewarded for avoiding homes and businesses. All the impacts would be in Montgomery and Prince George’s counties. A similar study of potentially widening I-270 north of I-370 and on to Frederick will be done separately, state officials said.

The state’s study so far has shown that as many as 34 homes and four businesses along the Beltway might have to be destroyed, while none would be taken along I-270. Nearly 1,500 properties total along both highways could lose parts of backyards or other land, either permanently or temporarily during construction. Greater noise could affect nearly 4,600 homes, businesses, schools and other sites.

Here's what to look for on the map:

The lines for Alternative 5 would be the narrowest option of adding one toll lane in each direction. However, this one seems unlikely, because state highway officials have said it would have numerous shortcomings, including the single toll lane becoming bogged down behind collisions or slow pokes. Alternatives 9 and 10 are the options that Maryland highway officials have said show the greatest potential travel-time savings and other traffic benefits.

Any land within those lines would be condemned via the state’s legal power of eminent domain. Under state law, property owners are compensated for “fair market value,” both for the land taken and for any diminished value to the property left behind.

Homes and commercial buildings outlined in bright yellow or purple dotted lines — some are hard to see — would be destroyed, and the owners would be paid the “fair market value,” highway officials say. Most are along the Beltway, just west and east of Georgia Avenue, in the Forest Glen area of Silver Spring.

Homes, businesses, parkland and other areas within the dotted red line would be exposed to noise above the federal threshold of 66 decibels because of additional traffic or because the highway would be closer. Amid 66 decibels of noise, people having a conversation three feet apart would need to raise their voices to be heard, state officials say. It’s also the noise level at which the state would consider mitigation measures, such as sound walls.

If it looks as though you could potentially lose a home or property, Post reporter Katherine Shaver would like to hear from you at