A traffic conundrum that stems from the Petaluma "road diet" has irritated police for months: Citizens parking and loading their personal cars in the new center lane on Petaluma Boulevard North that is meant for commercial vehicles.

"The city's traffic engineering team is trying to figure this issue out," said Petaluma Police Lt. Tim Lyons. "The city is trying to appease vendors who need to make deliveries, but also allow cars to drive in the center lane (to pass). But it's a double yellow line that, by definition, means no one is allowed to drive there."

Confusing the issue is the broken double yellow and diagonal lines that delineate the center lane. According to the California Vehicle Code section on divided highways, whenever a street has been divided into two or more lanes by an area wider than two feet and is marked by double parallel lines — which describes the center lane of Petaluma Boulevard North — it is illegal to drive any vehicle on it.

"The police department knows that the city wants people to use the lane as a commercial loading area and a lane for passing parallel parkers, but technically, no one should be driving on it," said Lyons. "We aren't ticketing people and we're trying to find a solution. But right now, regular people are walking and parking in the middle of the lane, doing their own thing."

It was Petaluma's controversial "road diet" that reduced the number of lanes on Petaluma Boulevard North from four to two between Washington and D streets, and added a center lane meant for passing and commercial loading. Though the project brought the street into compliance with federal safety codes and made conditions safer for bicyclists, pedestrians and parked cars by widening the lanes, it also slowed traffic in the area, often creating bottlenecks.

The project's center lane has opened the "road diet" up to even more issues. While the Petaluma City Council worked with staff to design a center lane meant for commercial vendors to have a place to unload their deliveries for downtown businesses, and a lane that could be used by drivers to pass parallel-parkers, Petaluma officials never intended for personal vehicles to park and load in the diagonally-striped lane.

When cars or trucks are parked in the center lane, traffic on the boulevard often grinds to halt, as was the case on the day before Thanksgiving when a Petaluma fire truck parked there with its parking lights flashing. Vehicles struggled to maneuver between the large, unmanned engine and the many people trying to parallel park. It's a regular occurrence on the boulevard, as vendors often unload in the center lane while afternoon traffic stalls around them.

City Engineer Larry Zimmer said that, while the center lane has caused confusion for the public, it is still safer than it was before the "road diet."

"Vendors and shoppers used to load and unload from an active driving lane," said Zimmer. "They would just stop their trucks in the middle of traffic and do their thing. So while it's not ideal, it's certainly better than it was."

Zimmer confirmed that personal vehicles are prohibited from using the center lane for anything other than passing vehicles that are parking. He said that city staff is continuing to study the effects of the "road diet" and will report any signal or signage changes that would help traffic and safety to the City Council next year.