Durable Growth, Transportation

The futile search for “achievable alternatives”: Why the apparent solution fails

E. Washington Street in Petaluma

E. Washington Street in Petaluma

In my last post, I introduced a question from a correspondent about “achievable alternatives” for traffic congestion relief.  The particular question pertained to the congested E. Washington Street in Petaluma and the proposed Rainier Connector that many believe would provide relief, but the question could apply to overloaded arterials everywhere.

In the earlier post, I explained how E. Washington Street became congested.   I also presented the Rainier Connector as the apparent solution in the minds of many.  Today, I’ll try to offer an explanation on why that conventional wisdom is wrong.  In my next post, I’ll offer the alternative ways of thinking about traffic that are provided by urbanism.

The Problem with the Proposed Solution:  The reason that the Rainier Connector likely won’t provide significant traffic relief is induced traffic.  It’s a concept that I’ve noted before, but today I’ll try to provide a deeper and more complete explanation.

Economists have a well-evolved vocabulary for many of the concepts I’ll try to explain below.  But I’m not an economist and would likely trip over my word choices if I pretended to be one.  So I’ll write in my own lay words.  And if the economists among the readers want to recast my arguments into the economist dictionary, please do so.

The root of traffic congestion, and the resulting problem of induced traffic, is related to how public agencies set, or don’t set, prices on scarce resources.

In the private world, the free market system with its rules of supply and demand usually governs.  Given tee times to fill at a top-rated golf course, the green fees are set high.  If surplus demand still remains, the green fees are bumped even higher until the demand for tee times eventually matches the number of tee times available.  Given rooms to fill at a nice hotel, the same rules apply.  Diamonds to sell?  Same rules.  Adjust the price until supply and demand meet.

The supply and demand system is marvelously elegant and intuitive.  And for the most part, it works well.  Some may not like the answers that pop out, but the market usually tends toward logical and rational.

But we, as represented by our various levels of government, typically have an aversion to the applying the same market rules to public resources.  We don’t want the best camping places going to millionaires driving tricked out recreational vehicles.  And we don’t want to dole out hunting permits only to the well-heeled.

So instead, we devise a range of non-price systems to allocate scarce resources.  Have a campground that’s usually full all summer?  Institute a policy that requires advance reservations on a first-come, first-served basis.  Managing a trail that has excess demand?  Devise a lottery for hiking permits.  Afraid that unfettered fishing will exhaust a stream?  Implement rules like catch-and-release, closed seasons, and catch limits to reduce pressure on the fishery.

But there are also public resources to which we don’t choose to apply significant impediments.  At the top of that list is street capacity.  Given that most people already have cars and drivers licenses, the only barriers to driving extra miles, whether on open country roads or congested downtown streets, is the incremental vehicle wear-and-tear and the cost of gasoline, neither of which is a significant barrier.

To understand the implications of this absence of obstacles to driving, let’s try a thought experiment.

Presumably all are familiar with the scenic wonders of Yosemite National Park.  Access to Yosemite is well-regulated by entrance fees, high cost hotel rooms, advance registration campgrounds, and hiking trail lotteries.

But imagine if Yosemite management decided that the barriers to park use were too high.  To allow more folks to partake of the park, they clear a meadow on the valley floor, throw a fence around it, and open it to unlimited camping use.  No reservations, no fees, no designated camp sites.  Just an open gate.  People could pitch tents wherever they wished, with no standards about how far they needed to be from other tents.  (To be clear, I’m not suggesting this idea.  I’m only offering it for thought purposes.)

What would happen?  Obviously, the campground would fill quickly and campers would soon be stepping on each other’s toes.  Some campers would give up and go home, deciding that a vista of Half Dome wasn’t worth being unable to warm one’s hands at one’s campfire without burning one’s backside on a neighbor’s campfire.  But plenty of campers with a high tolerance for crowding would remain.

Now let’s say that Yosemite management, looking at the “success” of the new campground, decided that the concept was valid, but that the overcrowding had become too burdensome.  To allow more spacing between tents, they decide to open a second campground with the same set of rules, arguing that the density of campsites will thereby be halved.

But that’s not what would happen.  Remember the campers who went away, turned off by the lack of space between tents?  They’d come back, happy to camp with even a little more space.  The congestion in the second campground would quickly rise to nearly the same level as the first campground.

Obviously, there would be some number of campgrounds that would satisfy the demand for cheap, no-frills Yosemite experiences, but the entire valley floor might be consumed before that point is reached.

And that’s exactly what happens with congested city arterials.  Some may argue that traffic congestion would disappear with new road capacity, but the reality is that campers drivers who had previously deferred trips would return to congest the new roadway.

Nor is this a hypothetical supposition.  Study after study shows that a large chunk of new roadway capacity is consumed on the day it opens, with the remainder consumed in next few years, even in the absence of new development.

This finding is why the State of California is implementing new rules to judge environmental impacts based on traffic generation, not congestion.  Unwilling to await the new state rules, the City of Pasadena implemented their own rules to the same end.

(Side note: When the Petaluma Planning Commission reviewed the Draft Environment Impact Report for the Rainier Connector, some Commissioners noted the surprisingly small congestion relief benefits projected as a result of the new road.  But under the pending revised California rules, which measure traffic generation in place of congestion relief, the balance would make the outlook even worse.  Instead of a minor benefit, the traffic impacts of Rainier Connector would be judged a negative.)

So when the correspondent asked about “achievable alternatives”, his underlying supposition was flawed.  Not only are there no achievable alternatives, but even the preferred solution of the Rainier Connector wouldn’t provide the promised benefits.  Induced traffic undermines any attempt to reduce traffic congestion by building new roads.

Urbanism can’t solve the problem of induced capacity, but it can offer a different land-use paradigm and set of tools that would make traffic congestion less of a daily problem.  The paradigm and those tools will be covered in my next post.

As always, your questions or comments will be appreciated.  Please comment below or email me.  And thanks for reading. – Dave Alden (davealden53@comcast.net)

Written by Dave Alden

Dave Alden

Dave Alden is a Registered Civil Engineer. A University of California graduate, he has worked on energy and land-use projects in California, Oregon, and Washington. He was also the president of a minor league baseball team for two seasons. He lives on the west side of Petaluma with his wife and two dogs. The blog that he writes can be found at http://northbaydesignkit.blogspot.com.

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