Early morning commuters board and disembark an Orange line train at the Courthouse Station in Arlington. (Nikki Kahn/The Washington Post)

Dear Dr Gridlock:

I often write you to complain about Metro, but today I have a different, but related topic. I like to have a contingency plan to get home if Metro is not working, or if there is some other problem.

One option is a cab, but some days that will not work because of gridlocked traffic. So I figure walking is an option, but I need to know the best route.

The day of the earthquake, I tried this. I work near McPherson Square. I headed over to the Arlington Memorial Bridge and went on the bike path that goes along the Potomac there.

The problem was that I had not researched this and so, while I saw there were paths headed off the main path, very few of them were marked and I was not sure where I should go.

Thinking long term for Metro

I ended up walking past Reagan National Airport and got into Crystal City, and then called hubby to come get me. I think there must have been a better way, so I am asking you and your readers for assistance.

My eventual destination is the Parkfairfax neighborhood, which is on the other side of Interstate 395 from Shirlington. Is there a path for pedestrians on the 14th Street bridge? How do I get there and where do I go once on the other side?

— Alice Cave, Alexandria

Cave has written several times with thoughtful comments about the minus side of Metro’s Rush Plus service. So I hope we can help her out on this question. And after Wednesday’s shutdown on the Green Line during the evening rush, other commuters may be considering sidewalk options.

I suspect many readers would scoff at that, and say Cave should just take a cab and endure the traffic.

But the walk she describes does not demand Olympian endurance, just some good planning and good shoes.

A trip from McPherson Square to the Parkfairfax neighborhood in Alexandria is a walk of about 6.7 or 7.5 miles, depending on the route. The first route, across the Arlington Memorial Bridge, should take about 2 hours 16 minutes. The second, across the 14th Street bridge, should take slightly less than 2½ hours.

I learned this by checking the route on Google Maps. A search on Mapquest, another online service, pops up a variation on the 14th Street bridge route. It’s 7.65 miles, with an estimated walking time of three hours and three minutes.

Pick up the walking path for the 14th Street bridge near the Jefferson Memorial. On the Virginia side, walk down the ramp and pick up the Mount Vernon Trail.

Follow that past Reagan National Airport and go west on the Four Mile Run Trail to West Glebe Road. Turn right on Valley Drive.

I agree that the Arlington Memorial Bridge route can get confusing. Start this part by swinging around the south side of the Lincoln Memorial and crossing the bridge along the sidewalk on the downstream side. Follow that path in Virginia as it bends to the south. Your target is Washington Boulevard, to the west of the George Washington Parkway.

Past the Pentagon, follow a route along Columbia Pike and South Joyce Street to get under Interstate 395. Then pick up Army Navy Drive. This route will work its way down to West Glebe Road.

I learned a lot about cross-river walking commutes from Peter Owen of Arlington. In 2008, he took me on one such trek, from his workplace near Union Station to his neighborhood near the Court House Metro station, via the Roosevelt Bridge.

Among the things I learned was that maps take you only so far. Actual experience counts, and sometimes getting lost leads to the discovery of a better route.

Owen would also evaluate routes by season, considering light to be an important factor, as well as safety. And he would be very aware that these miles-long routes require encounters with roads built to accommodate vehicles, not walkers.

What tips would you offer for long-walk commutes?

Dr. Gridlock also appears Thursday in Local Living. Comments and questions are welcome and may be used in a column, along with the writer’s name and home community. Write Dr. Gridlock at The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 or e-mail drgridlock@washpost.com.