Last year, a segment of Silver Spring’s University Boulevard shrank from six lanes to four to accommodate work to replace the bridge that passes over the Capital Beltway. There’s less room for cars to pass through the work zone, but traffic congestion hasn’t gotten worse.

The University Boulevard Beltway bridge under construction in May. Right now, the roadway is four lanes wide so it can accommodate the project. Photo by the author.

Prior to the construction project, University Boulevard had six total travel lanes, three that ran east and three that ran west. There was also a 14-foot wide exit lane onto the Beltway.

University Boulevard before work began, with six travel lanes and an exit lane. August 2010 image from Google Earth.

To replace the bridge, the Maryland State Highway Administration (SHA) had to make room for demolition and replacement work on the bridge deck. It did so by shifting all the traffic onto one side of the bridge and by narrowing the four remaining lanes to 11 feet.

University Boulevard reduced to a 4 lane undivided road during construction. October 2014 image from Google Earth.

Traffic congestion hasn’t gotten worse

Because it connects to the Beltway, this stretch of University Boulevard is one of the road’s busiest segments. According to SHA traffic counts from 2014, this part of University carries ~43,000 vehicles per day. Before the project began, some nearby residents were concerned that fewer lanes would mean backed up traffic.

But over a year into the project, that hasn’t happened.

I live in a nearby neighborhood and use the bridge daily to get to downtown Silver Spring. Even when schools are in session (Blair High School and Eastern Middle School are both on this segment, and the road sees heavy school bus traffic), I have not encountered any significant delay when passing through the bridge’s work zone.

Evan Glass, the immediate past president of the Indian Spring Citizens Association, the organization which represents the residents of the neighborhood adjacent to the bridge, hasn’t noticed any serious congestion issues on the bridge either.

“I haven’t experienced any major problems from the bridge reconstruction, aside from some noise due to nighttime work,” he told me. “I drive across the bridge regularly and drivers quickly learned to follow the new traffic pattern.”

Even on weekdays, traffic on the bridge is often light. This picture was taken on a Monday afternoon around 4 PM. Photo by the author.

This is a noteworthy outcome for the State Highway Administration

This construction project presents a rare opportunity to study the effects of narrowing an arterial road from six lanes to four.

An official study of this segment during this construction project could confirm and quantify what seems to be the case: that making a road narrower hasn’t made congestion worse.

It is generally accepted that adding traffic lanes actually makes congestion worse because it induces demand. Conversely, it’s not uncommon for less volume to travel on a road after you reduce its number of lanes (within reason).

This happened on Riggs Road in Chillum, with traffic volumes dropping 20% from 2010 to 2011 after the road shrank from six lanes to four (see page 31 of each PDF).

If such a well-traveled section can lose a travel lane in each direction without issue, concerns over congestion seem even less credible when applied to lesser-used parts of the road.

It’s not uncommon to see large stretches of University Boulevard empty, even at rush hour. Photo by the author.

Other nearby roads have been narrowed without adverse traffic impacts

Two nearby roads nearly identical to University Boulevard have been narrowed from six lanes to four lanes without problems.

Riggs Road got narrower a few years ago, with it’s former right travel lanes becoming bike and parking lanes. Queens Chapel Road in Hyattsville was narrowed about 10 years ago by closing the left lanes with striped paint, and it is currently undergoing a construction project to make the changes permanent.

This construction project has shown the University Boulevard is a good candidate for a similar lane-reduction treatment.