San Francisco transit officials have started a pilot program meant to curb driver behaviors at two intersections near Bay Bridge approaches.

The Municipal Transportation Agency’s SoMa Intersection Gridlock Enforcement Pilot evaluates the best way to change drivers from blocking intersections either on the crosswalk or in the middle of the intersection.

It’s known as box blocking.

Under California Vehicle Code 22526 Section A, it is illegal to enter an intersection unless there’s sufficient space on the other side of the intersection — even if the driver has a green light. That also goes for vehicles making a right turn at an intersection as well.

Erin Miller Blankinship, lead project manager, said the pilot addresses community concerns regarding traffic conditions and blocked intersections in the South of Market neighborhood near the eastbound approaches of the Bay Bridge:

“Concerns regarding traffic congestion and pedestrian safety in this neighborhood have been voiced many times over many years.”

On July 3 and 10, SFMTA officials surveyed existing traffic conditions at Main and Harrison streets and Second and Bryant streets between the peak hours of 3 p.m. and 5 p.m.

The transit agency found a total of 509 vehicles blocked the intersection and 515 vehicles blocked the crosswalk during 65 signal changes at the intersection of Main and Harrison streets. SFMTA officials also said vehicles impeded 182 pedestrians crossing the intersection.

At Second and Bryant streets, a total of 606 vehicles blocked the intersection, while 350 vehicles blocked the crosswalk. Staff found vehicles obstructed 1,343 pedestrians from the crossing the intersection.

On July 30 and Aug. 13, the SFMTA started its first pilot approach with two parking control officers issuing citations at the intersections.

A misunderstanding on Aug. 13 led to no citations issued at Second and Bryant streets, but parking control officers were at the intersection directing traffic.

During the two days, officials at the transit agency said they issued 162 citations totaling $16,931 in fines.

SFMTA officials found fewer vehicles blocked the intersection and crosswalk while parking control officers were present.

An updated report released by the SFMTA on Aug. 28 revealed only 90 vehicles blocked the intersection and 174 vehicles blocked the crosswalk on Main and Harrison streets.

Second and Bryant streets also a saw a decrease of vehicles blocking the intersection from 606 to 452, but vehicles blocking the crosswalk increased from 350 to 444 vehicles.

Transit agency officials said the limits and challenges in collecting data include traffic condition variations between parking control officer shifts, collecting data only on days the Giants played, unplanned field calls by parking control officers, human error in data collection and low sample size.

Blankinship said drivers were not asked during the pilot why they were blocking the intersection, but said it’s possible drivers lack the familiarity of the state vehicle code or just choose to ignore it.

The second final pilot approach, which started on Aug. 28 and will continue on Sept. 11, will have two parking control officers at both intersections again. One will manually direct traffic with hand signals and the other officer will issue citations, she said.

Changeable message signs will also be present to warn drivers in advance.

Blankinship said the pilot uses two focus areas — education and enforcement — of the City’s Vision Zero plan, which calls for zero traffic fatalities by 2024.

SFMTA officials plan to give an update on the pilot at the San Francisco Transportation Authority board on Sept. 30.