Some intersections in Northeast slated to be adjusted will include a signal strategy called Leading Pedestrian Interval, or LPI, which gives pedestrians a head start.
WASHINGTON — Almost a dozen intersections in the District will soon give pedestrians a potentially lifesaving head start.
Friday evening, the District Department of Transportation will tweak traffic signal timing at 384 intersections in Northeast and Southeast D.C.
Keeping cars, trucks, buses and bicycles moving through corridors is one goal, but Wasim Raja, associate director of DDOT’s traffic engineering and signals division, said another is to keep pedestrians from being hit.
Eleven of the intersections in Northeast slated to be adjusted will include a signal strategy called Leading Pedestrian Interval, or LPI.
“With LPI, the pedestrians waiting to receive the Walk signal will get a head start” before the corresponding vehicular traffic gets its green signal, Raja said.
Having the strategy in place eliminates the scenario in which pedestrians and vehicles get green lights simultaneously, which puts walkers trying to cross the intersection at risk.
“The leading time we provide is rather short — 3 to 5 seconds — but it does a great service because the pedestrian traffic gets to establish their presence in the crosswalk” before auto traffic gets its green signal.
Raja said the District began using the strategy about a decade ago.
“At the onset, the pace we were able to incorporate the LPIs were rather slow,” said Raja. But in recent years, during the ongoing optimization, DDOT has been “able to prioritize and implement it more and more.”
After Friday night’s work, a substantial number of D.C.’s intersections will have the pedestrian safety feature.
“The total number of LPIs in the District will be about 200, which is roughly one-eighth of the entire system,” he said.
DDOT’s work Friday will be the last of four optimization implementations.
“It’s simply not possible for us to optimize the entire city, which is 1,650 traffic signals, in one shot,” said Raja. “We had to break that up into four (groupings), which are more manageable.”
Raja said approximately 90 percent of the District’s traffic signals are pre-timed, while 10 percent are actuated by a pedestrian pressing a button at the intersection.
Here are the 11 intersections that will be optimized with LPI:
1st St. and K St., NE
8th St., K St., and West Virginia Ave., NE
8th St. and Maryland Ave., NE
9th St. and Massachusetts Ave., NE
17th St. and Benning Rd., NE
17th St. and C St., NE
18th St. and C St., NE
19th St. and C St., NE
Monroe St. and 12th St., NE
South Dakota Ave. and Vista St., NE
East Capitol St.and 9th S. NE
Like WTOP on Facebook and follow @WTOP on Twitter to engage in conversation about this article and others.