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Fact Check: Will a Sales Tax Hike Relieve Traffic Congestion?

The San Diego Association of Governments hasn’t been shy about touting the benefits county residents will feel if they pass its proposed ballot measure in November. One of the proposal’s major selling points is that the projects the measure would fund will relieve traffic congestion. We found SANDAG thinks of traffic relief differently than a typical commuter might.

StretchStatement: “SAN DIEGO COUNTY ROAD REPAIR, TRANSIT, TRAFFIC RELIEF, SAFETY AND WATER QUALITY MEASURE: Shall an ordinance be adopted to: repair roads, deteriorating bridges; relieve congestion; provide every community funds for pothole/street repairs; expand public transit, including improved services for seniors, disabled, students, veterans; reduce polluted runoff; preserve open space to protect water quality/reduce wildfires by enacting, with independent oversight/audits, a 40-year, half-cent local sales tax ($308 million annually) that Sacramento cannot take away?” reads the title and ballot language for Measure A, a countywide measure appearing on the November ballot (emphasis ours).

Determination: A Stretch

Analysis: The San Diego Association of Governments hasn’t been shy about touting the benefits county residents will feel if they pass its proposed ballot measure in November. One of the proposal’s major selling points is that the projects the measure would fund will relieve traffic congestion.

It’s that claim – that the measure would ultimately reduce congestion – that we’re fact-checking here, not the various other claims made in the ballot language.

The measure would levy a half-cent sales tax for transportation and infrastructure projects, raising $18.2 billion over the next 40 years. Roughly 42 percent of that would go to public transit projects, 14 percent to highways, 30 percent to individual cities to spend on local infrastructure, 11 percent on open space preservation and 3 percent on walking and biking projects.

“Pretty much all of those, with the exception of open space, will help our region address traffic congestion,” said Charles “Muggs” Stoll, SANDAG’s director of land use and transportation planning in an interview. “They all address congestion in various ways by increasing efficiency, adding capacity and giving people options that they don’t have.”

The ballot measure title is: “SAN DIEGO COUNTY ROAD REPAIR, TRANSIT, TRAFFIC RELIEF, SAFETY AND WATER QUALITY MEASURE.” The description that will appear on the ballot starts off: “Shall an ordinance be adopted to: repair roads, deteriorating bridges; relieve congestion … ” (Emphasis ours.)

The ballot language was carefully crafted. SANDAG polled residents on their biggest regional concerns, and the words used to describe the measure, from repairing roads to traffic relief to water quality, were the ones that performed best.

SANDAG also made the case that the measure would relieve traffic congestion during a recent “Ask SANDAG” session on Twitter.

But critics have hammered that claim and questioned how the agency can support the argument that the investments it plans will relieve congestion. We wanted to examine the promise that the tax hike would lead to traffic and congestion relief.

In an interview, Stoll and SANDAG planner and ballot project manager Rob Rundle said new carpool lanes would add space onto existing roads, public transit would remove some people from roads and other projects in the measure will clear out specific bottlenecks.

For example, the measure would make money available to local cities to improve intersections where roads and trolley tracks cross, decreasing the time spent waiting for a trolley to pass. It would help synchronize traffic lights and increase frequency of existing transit services. That will attract more users.

“Those programs provide direct congestion relief to specific choke points in the system,” said SANDAG spokesman David Hicks in an e-mail.

Local governments often claim infrastructure projects will decrease traffic congestion. It’s something that’s been studied a lot. Most of those studies haven’t found empirical evidence to back that claim.

Thus the question isn’t just about what projects will be built, but about what effect they’ll have on our commutes. We found SANDAG thinks of traffic relief differently than a typical commuter might.

It may just mean things don’t get as bad as they could. SANDAG officials admit they can only help some commutes and maybe only for a limited time. Regardless what they do, they said, the region will grow and that means more people trying to get from one place to another.

Gilles Duranton is a professor of urban economics at the University of Pennsylvania, and an author of one of the most cited studies on the topic, “The Fundamental Law of Road Congestion: Evidence from US Cities.” When I read him SANDAG’s ballot title, he laughed.

“That’s an argument they make over and over again without any evidence whatsoever,” Duranton said.

Duranton and Matthew Turner, his co-author, studied metropolitan areas across the country. They found that on average, the amount of people that roads can accommodate and the amount of traffic they generate increase proportionately. When you make roads bigger, more people use them, and traffic stays the same. They also found that after building new public transit projects, within 10 years the people who left the roads to ride transit would likewise be replaced on the road by others.

“The notion that you can build your way out of congestion is just false,” Turner said. “There’s this big, latent appetite for driving and as we make it easier, people drive more.”

There are several reasons why building more roads and increasing public transit won’t change congestion on major roadways, said Duranton and Turner.

The first is people make decisions based on traffic. They may choose to take local roads instead of major highways or choose to go out to dinner in different parts of town to avoid traffic. If it seems like traffic improves, they’ll change their behavior.

The second is commercial traffic. As soon as there is extra space on the road, commercial delivery trucks and vans will use it. Hundreds or thousands of extra trips for them from that space could amount to a lot of money each year.

And finally, more people will move to a region.

SANDAG can improve bottlenecks at certain intersections or where trolleys and cars cross, but new choke points are bound to emerge elsewhere, Turner said. The traffic in the entire system won’t change.

“Our research says if you have a policy of fixing those things over and over again, you’ll end up back where you started,” he said.

But SANDAG isn’t necessarily arguing the tax will make congestion better than it is today. Instead, Rundle and Stoll said it will keep congestion from getting worse as the regional population grows.

SANDAG measures its success, Rundle said, by how it manages to cut down on the number of miles the average person drives. He said reducing the amount of total driving in the region would be unrealistic since the population is growing.

Decreasing the amount the average person drives could mean encouraging some people to take transit or ride a bike. Under SANDAG’s plan, each person would drive slightly less on average in 2035 – 23.5 miles per day – than they did in 2012 – 25.2 miles per day.

Hicks said that decrease is evidence SANDAG’s tax reduces congestion.

“Preventing the system from degrading over that time (and in many areas making it better than it is now) should be considered ‘congestion relief,’” he wrote.

But as a general matter, the number of miles the average person drives isn’t the same thing as “congestion.” Congestion is the delay drivers experience when more people are using a road or freeway at a particular time than the road or freeway can handle.

The Texas A&M Transportation Institute measures congestion in urban areas across the country each year in its Urban Mobility Scorecard. The scorecard found that a travel trip during rush hour in San Diego takes 24 percent longer than a free-flow trip. That means that a trip that would normally take 30 minutes takes roughly 37 minutes in rush hour.

Hicks also said new projects could keep rush hours of the future the same length as today, even with population growth, saving San Diego from the fate of Los Angeles, where peak traffic periods have increased to more than just a few hours per day.

According to SANDAG’s own projections, that could be true for some people. Some commutes will get worse. Some will stay the same.

The commute by car during rush hour from Oceanside to downtown San Diego, for instance, will go from 65 minutes in 2012 to 59 minutes in 2035 if the projects are built. In 2050, that commute would increase to 62 minutes. If the projects weren’t built, the commute would be 67 minutes in 2035 and 74 minutes in 2050.

But from Escondido to downtown San Diego, the rush hour commute in 2012 was 56 minutes. In 2035, if the projects were built, it would increase to 58 minutes and then to 60 minutes in 2050. In 2035, without the projects, the commute would be 59 minutes and 63 minutes in 2050.

From San Ysidro to downtown San Diego, the commute would decrease by one minute between 2012 and 2050 if the projects were built. From western Chula Vista to Mission Valley, the commute would stay the same at 29 minutes between 2012 and 2050 even with the new projects. Without them, it would increase to 37 minutes.

Turner said it’s common for agencies to argue their improvements will keep things from getting worse.

“That might be true, but I haven’t seen empirical evidence to back that claim,” he said. “And if you’re asking people for $18 billion, you’d want more than ‘might be true.’”

A SANDAG document says all the projects the agency plans to build could save roughly 1 billion hours of driving, because people will have more public transit alternatives. The document also says, however, that those people who continue to drive to work without carpooling, overall, won’t see any change in their commute times.

“Travel times to work remain flat for driving alone and improve for transit users,” reads the document.

The only thing that has ever been proven to actually reduce congestion, Turner said, is congestion pricing – making people pay to use roads. London and Singapore have done so.

Turner compared U.S. highways to Soviet Union bread lines. When it’s free, people line up and it’s first come, first serve. But then there’s a continual shortage.

SANDAG studied congestion pricing, but dismissed it because it would require new state legislation.

One other piece of SANDAG’s ballot title jumped out at Jarrett Walker, a transit planning consultant and author of the book “Human Transit: How Clearer Thinking about Public Transit Can Enrich Our Communities and Our Lives.” It seemed intentional to him that SANDAG promised to “relieve” congestion, and not “reduce” it.

“’Traffic relief’ can mean relieving people from traffic by giving them an option other than sitting in traffic,” Walker wrote. “’Reduced congestion,’ on the other hand, would mean a benefit to motorists who are still on the congested highway. See the difference?”

Stoll said he doesn’t know if that much thought went into the word choice, but said SANDAG isn’t claiming it could eliminate congestion.

“We’re not trying to say if we do this measure, there will be no congestion anywhere in the system at any time,” Stoll said. “’Relief’ kind of suggests that we’re doing what we can to make some key investments in key corridors that can help by either freeing up space, keeping congestion contained in that peak period or giving them other options.”

We consider a statement to be “A Stretch” if it takes an element of truth, but omits critical context that will significantly alter the impression it leaves.

That’s the case here.

For typical voters, traffic congestion means cars on the road, one behind another, inching along and slowing the amount of time it takes to get somewhere.

The measure would provide options for some people to get off the roads who don’t want to deal with traffic. It might make improvements at certain intersections or on certain roads that will benefit certain people at certain times. If you’re a carpooler, it might add a carpool lane to your commute that wasn’t already there.

That’s not the same thing as reducing congestion.

“As you develop rail and busway transit, a higher and higher share of the population (and the economy) is no longer impacted by traffic congestion,” wrote Walker. “That doesn’t reduce congestion, but it does increase liberty, equity and prosperity.”

That’s not to say the measure is good or bad, but it probably won’t significantly reduce traffic congestion in the region.

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