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Friday, May 27, 2022

City Making Improvements at Most Congested Intersections

City Making Improvements at Most Congested Intersections


Staff Reporter

Traffic improvements don’t always happen through massive projects like the $68.5 million 2.5-year effort to transform the Santa Monica Boulevard corridor. They can be as simple as adding a left-turn arrow at a busy intersection.

Fifty L.A. intersections rated by city transportation officials as the most dangerous or congested either have been upgraded or soon will be under a plan launched last summer by Mayor James Hahn, who made traffic improvements a centerpiece of his campaign.

To date, all but one of the first batch of 25 intersections announced for changes have been fixed. Hahn rolled out his next batch of 25 intersections in March. Work has begun on five of those. The mayor promises 25 intersections will be overhauled each year he is in office.

Changes range from installing left-turn signals and adding left-turn lanes to adding beacons that warn pedestrians they are entering intersections too late to make it across safely.

The cost of these measures: $1 million a year.

Ten of the first 25 intersections are in the San Fernando Valley, the epicenter of the secession movement. Ten of the second 25 are in the Valley, although they are still in the design stage.

The question, of course, is will these changes actually work to make the intersections safer or less congested? It will take several more months of monitoring before conclusions can be drawn, but traffic planners point out that even the most common remedy, adding a left-turn arrow, involves a tradeoff.

“The public likes left-turn arrows, since it’s easier to make protected left turns,” said Michael Meyer, a principal in the L.A.-based consulting firm of Meyer, Mohaddes Associates Inc. “But because they lengthen the signal cycle, they take away from the overall ability to serve through traffic. That’s why you don’t see them at every intersection on major through streets.”

For this reason, Meyer said, L.A. had a longstanding policy of not installing left-turn arrows. Public pressure has forced a relaxation of that policy.

Now, Meyer said, traffic engineers generally settle on a compromise: set aside a short period in the signal cycle for left turns, leaving the majority of the time for through traffic. Also, he said, many left-turn signals only function during certain peak traffic hours, leaving drivers in off-hours to negotiate left turns against oncoming traffic.

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