Durable Growth, Transportation

Putting the automobile in its place

Petaluma Boulevard South at Center Park

Petaluma Boulevard South at Center Park

Urbanists don’t dislike cars.  Despite the accusations of those who fear challenges to the status quo, urbanists believe the automobile to be a remarkable innovation, essential for many human activities.

But urbanists also believe that our communities have been excessively shaped to accommodate cars.  We’ve widened streets to more easily remove people and vitality from urban cores, the concept that Jeff Speck calls “car sewers”.  We allowed so much parking that the few remaining pedestrians have little at which to gaze except bumpers.  We’ve reconfigured our homes so that garage doors are often the dominant feature.  And we’ve made it impossible for many to buy a gallon of milk without using an ignition key.

Urbanists believe that we need to rebalance our approach to cars so that cars appear to be serving us, not the reverse.

There are a number of tools available for this task, including providing housing within walkable distance of shopping and transit, widening sidewalks to create places conducive to gathering, and placing parking in less obtrusive locations. Another tool is road diets.

About a year ago, while writing about a related topic, I offered an introduction to road diets.  From that post, “A road diet is a reduction in the travel lanes of an existing street, converting some of the pavement area to other uses, such as additional parking, center turn pockets, or sidewalks bulbs for traffic calming.

“Although reducing travel lanes would intuitively seem to reduce traffic capacity, the reduction can be less than expected.  If the existing lanes are unusually narrow, … the current capacity may be less than indicated by the lane count.  Meanwhile, the revised configuration can improve vehicle and pedestrian safety.”

I was writing about a proposed road diet in Petaluma that was under design at the time.  Since then, the project has been completed.  Combined with an earlier road diet phase, much of Petaluma Boulevard through downtown Petaluma has been converted from four lanes to two.

The Petaluma Boulevard road diet was controversial.  Many didn’t believe that road capacity could be maintained despite the fewer lanes.  Others were quick to find fault with the traffic in the first days after the road diet was complete.  As a result, the City Council asked for a report on the road diet results.  The City Engineer is scheduled to present preliminary findings at the October 21 council meeting.

I suspect that much of the response to the road diet has been comprised of auto-confirmations (pun intended), with those who expected the road diet to fail now finding that it has failed and those who believed it would succeed are also finding confirmation.  It will be good for the discussion to have actual data.

At a meeting I attended last week, the City Engineer described some of his initial data.  I won’t undercut his presentation by repeating his comments here, but I’ll suggest that anyone interested in the Petaluma road diet and in the hopes of reassessing our relationship with the automobile should attend the October 21 meeting.

In the meantime, readers are encouraged to post their own comments on the road diet below.  If the conversation is good, particularly if it is data-based, I’ll pass the comments along to the City Engineer.

Which opens the door for my own thoughts.  I was hopeful that the road diet would work, making Petaluma Boulevard a safer place for bicyclists and a more comfortable place for pedestrians.  And I thought the previous traffic capacity, with four reduced-width lanes, might not be significantly different than the new traffic capacity with two normal-width lanes.

Therefore, my initial reaction upon completion of the road diet was consternation.  Congestion, particularly queuing at signals, seemed noticeably worse.

An often-overlooked fact of traffic engineering is that lanes do more than allow the movement of cars.  They also provide a place for stopped traffic to wait for a signal change.  Assuming the same number of stopped vehicles, the queue on a two-lane street will extend twice as far as on a four-lane street, making traffic signal timing crucial.

(Traffic storage is the same reason many single-lane freeway off-ramps quickly widen to two or more lanes.  The extra lanes provide a place for vehicles to wait before joining the surface street, preventing a potentially disastrous backup onto the freeway of stopped vehicles.)

To their credit, City Public Works anticipated that traffic signal timing might need tweaking.  Computer models are great, but sometimes real world data, with us drivers as the guinea pigs, is required.  Public Works had set aside funds to make adjustments.  Over the first few weeks of the road diet operation, fine-tuning was done and the road diet seemed to move closer to success.

But there are still occasional hiccups.  A local architect astutely observed that congestion can quickly build up, and only slowly dissipate, when a driver does a poor job of parallel parking.  If two or three passes are required to successfully park, the congestion can linger for several minutes afterward.  But drivers are unwilling to pass on a scarce parking place, so continue to maneuver despite a growing line of cars.

Thus, it’s possible that a parking management program will be required before the road diet can achieve its full potential.  Parking management could mean many things, from increased enforcement of prohibitions on employee parking to parking meters.  Either way, the typical goal of a parking management plans is to ensure that there are always a few parking spaces available, making drivers more willing to pass on the undersized space where parking may be difficult and slow.

Those are my thoughts on the road diet.  I’ll await yours.  And I remain hopeful that we can find a way to coexist with cars more comfortably.

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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