Thursday, April 24, 2014

MoCo's congested intersections aren't in its downtowns

Where do you think the most congested intersections are in Montgomery County? Maybe right by the Bethesda Metro? In downtown Silver Spring? University, Georgia, and Veirs Mill in Wheaton? Actually, no. A review of Montgomery County's 50 most congested intersections found only one inside one of the county's urban centers.

Busy intersections form a ring around downtown Silver Spring. Map by the author.

County planners ranked the busiest junctions for its Mobility Assessment Report, a regular review of Montgomery's transportation needs. (You can see the full list here.) Notably, the report found that the amount of driving in the county has stayed the same since 2002 even though it added 100,000 people.

The busiest intersection is Rockville Pike at West Cedar Lane in Bethesda, next to NIH and Walter Reed, which had a critical lane volume of 1,957 cars during morning rush hour. In other words, that means that nearly 2,000 cars pass through a single lane of that intersection each morning. In second place is Rockville Pike and Nicholson Lane in White Flint, which is slowly evolving into a new downtown.

Other than that, the top 50 didn't contain a single intersection in the downtowns of Bethesda, Silver Spring, and Wheaton, in Friendship Heights, or Rockville Town Center. For decades, Montgomery County has had a policy of directing growth to walkable, urban neighborhoods near transit stations with an aim of reducing car traffic.

As a result, while these areas do have higher-than-average rates of foot and bike traffic and high rates of transit use, they're not as congested as more suburban parts of the county. Just 16 of the top 50 intersections were inside the Beltway.

Layhill Road and Norwood Road. Image from Google Street View.

Not surprisingly, some of the busiest junctions are along major commuter routes like Rockville Pike, Connecticut Avenue, and Georgia Avenue. But many are on small, two-lane roads in suburban or rural communities like #4, Darnestown Road and Riffle Ford Road in North Potomac, or #46, Layhill Road, Ednor Road, and Norwood Road near Sandy Spring. These places are spread-out and far from transit, jobs, and other amenities, meaning residents have to drive a lot.

This report shows that if you build places on the assumption that people will drive everywhere, you'll get a lot of traffic, while if you give people options, you'll get less. Not everyone may want to live downtown, but those who choose to do so are keeping the roads clear for everyone else.

1 comment:

Glenmonster Silver Spring said...

Interesting map. Surprised to see the that Randolph and Georgia didn't crack the top 50 given the construction of the new interchange (finally). Hopefully this suggests that more folks are using Glenmont Metro.

While there's only one dot inside the urban center, I wonder if folks park outside the core and find a different way in. The dots in the Forest Glen area are interesting because there's not much there, so these folks must be commuting to a job center (DTSS, assumedly). It's be interesting to study where said persons are coming from and going to.

Whatever the case may be, this is a great argument to keep funding transit. It works!