With schools starting, September traffic surge expected

WASHINGTON — An analysis by the National Capital Region Transportation Planning board said that traffic will get worse starting next week, doubling the delay drivers have faced this month in some spots.

The review of six years of traffic data finds a consistent “September shock,” with morning travel delays across the region increasing an average of about 30 percent each year in September over traffic levels in August.

“What this really is is a phenomenon of when people travel,” Transportation Planning Board’s Ben Hampton said.

This September shock effect is mainly a morning phenomenon, so you just really need to think more about leaving earlier in the morning or maybe leaving a little later in the morning. There’s not really a discernible trend in the afternoon, so you don’t have to focus so much on that, but it’s changing travel times or picking other ways to travel,” Hampton said.

In the early morning hours, the most dramatic changes from August traffic are largely concentrated in areas far from the Beltway, such as Frederick County, Maryland, and parts of Loudoun County in Virginia.

In the evening hours, the increase in delays is most significant on stretches of roads such as Interstate 66, the Wilson Bridge, as well as some more local routes.

The analysis does not find anything particularly striking about the Tuesday after Labor Day, but it indicates that the return to school and work really does have an impact on the roads.

“One of the big effects that we think is going on is, because schools are in session, parents have less flexibility in the morning as to when they leave to go to work, so that means more of them are trying to hit the road at the same time,” Hampton said.

In October and November, the traffic consistently drops off.

“It’s probably the case that people are kind of shocked in September and then start to adapt their travel patterns, so if we’re trying to look at things we can learn from October that we might be able to apply to September, it’s things like adjusting your morning travel time either earlier or later to avoid what are already some pretty bad backups. But it could also mean that September’s a really good time to look at teleworking options to avoid being on the road altogether, or other alternatives in the region,” Hampton said.

Transportation Planning Board Senior Engineer Wenjing Pu said government agencies can use the data to help prepare for September’s traffic surge. “This year we also have SafeTrack, so maybe that’s one more layer of complexity,” he said.

Metro’s 24/7 track work affects the Blue Line until Sept. 11, and creates a major disruption on the Orange Line beginning Sept. 15. Further track work schedules will be announced around that time.

Planners hope commuters will see the full impact of the September traffic spike and still consider other options such as telework, carpools, biking and buses.

“When there’s congestion in our region, the whole region suffers … if we can just change the travel behaviors of some people and bring that overall congestion number down, then I think the whole region benefits,” Hampton said.

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