No easy fix for traffic light troubles

The much-maligned intersection of East Washington Street and McDowell Boulevard continues to spark driver complaints one year after a traffic signal coordination plan was implemented.

Heavier-than-anticipated vehicle traffic and increased pedestrian crossings have stymied the improvements that the public works department had hoped would significantly enhance traffic flow. Despite incremental improvements, local officials now acknowledge that cross-town traffic from west to east may not see significant improvement until the Rainier Crossing is built – a project that remains several years away from completion.

“I dread going from the west side to the east side,” commented Petaluma resident Lindsey Ladd on Petaluma360.com’s Facebook page. “Sometimes takes me 10 minutes to get from the swim center to Trader Joes,”

She’s not alone.

“Though it’s two lanes, only the first two or three cars make it through (a green light) and it’s backed up to Safeway,” said resident Barb Brooks.

“I’ve sat through three cycles and that’s the norm for afternoons.”

Comments like these demonstrate that for many Petaluma drivers every day, the improvements are not nearly enough, if they work at all.

It may be small relief to know that the city public works department feels their pain.

‘Bad intersection’

“It’s a bad intersection,” admits Public Works director Dan St. John. He went on to call it “the most impacted intersection in Petaluma,” but pointed out that a traffic improvement project implemented a year ago had demonstrably improved the situation. “It’s better. Is it as perfect as I want it to be? No.”

That project was completed by the city in cooperation with CalTrans and the Metropolitan Transportation Commission, a Bay Area agency. Its focus was the coordination of traffic lights on East Washington to improve traffic flow for the estimated 40,000 cars that use the corridor daily.

Projections for the Program for Arterial System Synchronization (PASS) showed that it could produce an average 12 percent decrease of travel time, 9 percent fuel savings and total benefits of almost $1.5 million over a five year period.

A city study in the weeks following the PASS implementation did show reductions in travel-time and signal delay.

But the complaints show no signs of abating. A recent online Pulse of Petaluma poll also showed negative impact on commuters’ lives from city stoplights.

City Engineer Curt Bates said that the city had received only “a few” complaints via their public input mechanisms, including email, phone calls and online complaint forms. Still, he conceded that the traffic volume in the area may well be higher than that planned for in the traffic coordination program.

The signal coordination project was based on traffic pattern studies conducted at least a year before the plan went into effect. In the meantime, the city officials admit they probably have outmoded data - all the more so given the evident increase in traffic due at least in part to the improved economy.

“We see this in the peak hours, especially during work, shopping, and school related periods,” said Bates.

Bates said that the department is considering applying for a new grant to update the traffic study information, but that it would probably be at least another year before grant funding would come together.

How signal timing works

The purpose of signal coordination is to keep the greatest amount of traffic moving in clusters through a series of intersections, then switching to allow cross-traffic to move as well.

Signal coordination uses fixed signal duration during key periods daily - typically between 7-9 a.m., the lunch rush from 11 a.m.-1 p.m., and again from 4-6 p.m. all along Washington Street..

For most of the street this is a 110-second cycle length, almost two minutes. In the downtown area, the cycle length is 96 seconds, and farther west on Washington at Webster and Bantam it’s a brief 80 seconds.

The rest of the time, the signaling system senses the traffic in or approaching the intersection through loops of electrical sensors buried in the pavement. When there’s traffic present, it tells the signal to switch and let cars through.

This so-called “free mode” makes off-peak traffic flow seem easier and faster, but the system is not smart enough to deal with high-volume periods.

A bigger problem

Signal coordination is not the whole story. Especially at the besieged intersection of McDowell Blvd. and East Washington, pedestrians and emergency vehicles can interrupt the ideal traffic flow the coordination promises. So a pedestrian at the corner who wants to cross from the Best Western Inn on the west side of McDowell to get to the Peet’s in the shopping center on the east side pushes the button and waits for that green Walk sign.

At certain times of day, there are a lot of pedestrians crossing at the intersection in all directions. Pedestrians have priority over traffic.

Emergency vehicles have even higher priority - an approaching ambulance, fire truck or police car isable to notify the signal computers at the intersection that they’re on the way.

But every time a pedestrian pushes that button or a police car wails through, the finely-tuned signal coordination is thrown off. It leads to longer signal length to adjust the traffic signal software to allow the signal pattern to catch up, and it may take a couple cycles to adjust - until the next pedestrian wants to cross the street.

Who funds changes?

When asked if a hybrid model of traffic control exists that combines coordinated signal timing and free mode traffic sensing, Bates said, “There may be other systems, but that’s the way Petaluma has done it.”

He pointed out that coordinated signalization is widely used as the most efficient way to handle large-volume traffic corridors, and noted other examples of it at work on Santa Rosa Avenue, Mendocino Avenue and Steele Lane in Santa Rosa.

There are several future projects designed to alleviate the overburdened situation - and perhaps it’s no surprise where the solution lies.

“Every traffic modeling we do shows that the Rainier crossing would have a significant positive impact on the East Washington/McDowell intersection, and improve traffic flow overall,” said Bates.

“The biggest relief would be Rainier, that’s what the traffic studies tell us,” concurred St. John.

But the Rainier crosstown connector project won’t be completed for quite some time, and is on hold until monies are found to widen Highway 101 through Petaluma.

St. John goes on to take an even wider focus, one plainly beyond his job’s ability to solve.

“What you are seeing locally is part of a regional, state and national crisis,” he said emphatically. “It’s being discussed from the President on down, in every city council and statehouse.”

Repairing roads and building traffic congestion projects, even the installation of “smarter” traffic signals, are all dependent on funding. Most of any city’s budget goes toward operational maintenance, not new projects.

“It is dire. Funding for these things is a national crisis,” St. John repeated. “It’s good we’re talking about it, but you should know we’re doing what we can. It’s funding that’s the challenge.

(Contact Christian Kallen at argus@arguscourier.com)