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When the Road Isn’t Neutral

Does Seven Locks Road cause accidents?

When Byron Bloch saw the news of a fatal traffic accident on Seven Locks Road, he felt like he had déjà vu.

“It turns out that that section of road has had accidents before,” said Bloch, an auto safety expert who lives in Potomac.

In late June a 17-year-old Chevy Chase resident was driving Northbound on Seven Locks Road between Bradley and Democracy. Her vehicle crossed the centerline and collided with a motorcycle, killing its driver and injuring its passenger.

Although the driver of the northbound vehicle has been found to be at fault, no charges have been filed, said Montgomery County Police spokesman Derek Baliles. The investigation is continuing, but “no other conclusions have been reached yet,” Baliles said.

At present, the Montgomery County Department of Public Works and Transportation (DPWT) is not engaged in a study of the area. “A study was done on Seven Locks Road, but it was further north,” said Ester Bowring spokesperson for DPWT.

Bowring noted that residents are free to request that traffic studies be done at any time (see sidebar).

If a study is done on this road, many variables would be taken into account, such as number of cars, average speed and measurements of the road itself. “There are just so many factors,” Bowring said.

The findings of the study would be compared against standards at both the state and national level. “It’s spelled out in very great detail,” Bowring said.

While she could not comment specifically on this section of Seven Locks, Bowring indicated that sometimes a review will reveal that the road needs to be updated.

In some cases, development around a road has created more traffic then the road was designed to handle.

In others, vehicles travel at speeds faster then the road is designed to accommodate safely. “Sometimes, we see that the engineering could be improved,” Bowring said.

The contours of Seven Locks Road may have been a contributing factor in the accident, Bloch said. It doesn’t mean a driver who crosses the center line in blameless, since hundreds of vehicles drive that stretch daily without incident.

“But the road should not contribute, it should be neutral,” he said. “Even if it’s only one in 10,000 trips, that’s too great a price to pay.”

Bloch remembered a similar accident about two years ago in the same location.

“A woman driving in a Mercedes was drawn into the southbound lane and was killed,” Bloch said.

He thinks that the road itself may have played a significant part in the accidents.

While most of his work focuses on the part that vehicle design can play in causing an accident, he sometimes has to take into account road conditions such as obstructed views or highway design. “Occasionally that becomes part of the mix,” Bloch said.

When driving north on Seven Locks, particularly between the old post office (now Avatamska Vikara) and the Seven Locks Swim and Tennis Club in the vicinity of Charleston Drive, the road is angled in such a way that if a driver is not paying attention, the car will track across the centerline.

“If momentarily … I was not tracking on Seven Locks, the vehicle itself would go over the centerline,” Bloch said.

Bloch demonstrated the fault by driving north in his own vehicle. While traveling at the posted 35-mph speed limit, the vehicle was almost fully across the centerline in a matter of seconds, traveling only a couple hundred feet.

He explained a principle of road design called “forgiveness,” which states that the road design should take into account that most people will have an occasional brief lapse in their attention to the road. Dialing a cell phone number, checking a map in an unfamiliar neighborhood, or just putting together a mental grocery list are all example of such distractions.

Without a full study, Bloch is not sure exactly what would need to be done to fix the road. He believes that a roughly 400 foot section of road would need to be torn up, so that the ground underneath could be leveled, and then the road would be repaved.

“It’s just a badly contoured road,” Bloch said.