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Study: 405 Freeway traffic flows better over the Sepulveda Pass

June 2, 2015

By Dana Bartholomew, Los Angeles Daily News


It took nearly five years and two "Carmageddon" shutdowns. But a year after the 405 Freeway widened for a carpool lane over the Sepulveda Pass, traffic is flowing better than ever during rush hour, according to a study released Friday.

The $1.1-billion 405 northbound carpool lane has boosted the number cars and people driving from Los Angeles over the hill and into the San Fernando Valley while cutting down the weekday afternoon rush hour.

"(It) was an important investment in our transportation system and a good use of both federal and state funds," Rep. Brad Sherman, D-Sherman Oaks, who was instrumental in securing the federal construction dollars, said in a statement. "If we hadn't built the lane, traffic would be much worse … through America's most crowded highway bottleneck."

The 8-mile stretch of the high-occupancy-vehicle lane between the 101 Freeway and Wilshire Boulevard was completed in May 2014, completing a continuous 36-mile carpool route to Orange County.

The new study, commissioned by the Los Angeles County Metropolitan Transportation Authority, contradicts a different study last fall by traffic analysts INRIX that said an afternoon rush hour commute took a minute longer than before the carpool lane.

According to Systems Metric Group, which compared traffic flow on the 405 before and after the Sepulveda Pass project added a northbound carpool lane, congestion has been greatly reduced.

According to the study:

-- The afternoon weekday rush hour now runs from 3 p.m. to 8 p.m., an hour shorter on either end, cutting rush hour on the Sepulveda Pass two hours.

-- Northbound 405 vehicle capacity increased 15 percent, with the number of people growing 30 percent, with cars and trucks increasing from 10,000 to 11,700 per hour at peak times.

-- Travel times on the northbound 405 now vary less, for more predictable commutes. Traffic on nearby surface streets is now 25 percent lower since construction ended.

On the downside, researchers said that overall traffic times on the 405 Freeway from Interstate 10 to the 101 Freeway have increased slightly, with the exception of afternoon rush hour. The increase, according to the report, can be attributed to a bottleneck at the 118 Freeway interchange.