Monday, April 13, 2015

Easing the Pressure on the Gas Pedal

In my last post, I began to write about an on-line neighborhood chat on the subject of teenager drivers traveling with excess haste on residential streets.  However, I was distracted by the participants in the chat, many of whom belong to my generation, calling for reduced freedoms for high school students.  The advocacy was sufficiently unexpected that it took me down a path of memories of student battles fought and student freedoms won when I was young.

Today, I’ll stay on topic.

The on-line chat, which happened during the run-up to a meeting between the administration of the nearby high school and concerned neighbors, was an attempt to list the topics that the neighbors wanted on the agenda.  The most significant concern, by far, was speeding and other aggressive driving behavior in the surrounding neighborhood.

Being a resident of the neighborhood, I can confirm that the issue is legitimate.  I don’t find the driving to be so obnoxious that it affects my everyday life, but there are a handful of drivers who consistently drive with unreasonable aggressiveness.  A neighbor recently told me of being passed on her street while she was driving near the speed limit, a driving decision that is clearly inappropriate in a residential neighborhood, especially a walkable residential neighborhood.

Having identified driving as the principal worry, solutions were offered by the parties.  Someone suggested a need for speed bumps.  Someone else correctly noted that most fire departments don’t allow speed bumps because they slow emergency vehicle response times.

The conversation then turned to increased policing, either through the use of local police or through the neighbors reporting license plate numbers to the school.

Before wandering off into questions of closed campuses and dress codes, someone stated that, student driving concerns aside, it nonetheless remained true that the streets had been built for cars.

Although I didn’t have the time to participate in the conversation, there many comments I wanted to interject.  This is my chance.

Vertical Traffic Calming: Speed bumps belong to a group of traffic management tools generally known as vertical traffic calming.  Related tools are speed humps, which are widened speed bumps that can be driven safely at speeds of 20 mph or more depending on the design, and speed tables, which are expanded areas of raised pavement, often at drop-off points for stores, and are intended to make drivers feel as if they are in the pedestrians’ realm, rather than the pedestrians being in their realm.

It’s true that fire departments generally oppose vertical traffic calming on the grounds that it slows emergency vehicles.  Personally, I find the opposition is a fine example of giving infinite weight to one decision element, emergency response time, over another decision element, slowing everyday traffic.

Of course, bringing more reason to fire department policies will be a long and difficult battle.  In the meantime, we can observe the irony of fire departments arguing for public safety by arguing against measures that would slow traffic.  I love a good bit of irony.

Horizontal Traffic Calming: Although still not a favorite of fire departments, horizontal traffic calming is more likely to gain approval and can often be more successful at reducing speeds.  It was a disappointing, but not unexpected, that the chat participants didn’t even mention horizontal traffic calming.  Although effective, horizontal traffic calming measures are not among the tools of which most people think.

Typical horizontal traffic calming measurements are reduced lane widths through paint or relocated curb lines, bulb-outs at intersections, reduced curb radii at intersections, and even parking that alternates between sides of the street, resulting in a chicane for drivers to traverse.

The SMART Codes that many cities, including Petaluma, now use to regulate their downtowns include a number of horizontal traffic calming measures.  One can visit the Theatre District of Petaluma to observe lesser lane widths and bulb-outs.  The recent Petaluma Boulevard road diet also includes horizontal calming.

Horizontal calming is important because it induces drivers to reduce speeds by making them feel uncomfortable at higher speeds.  As California speed limits are set by the actual measured speeds of drivers, horizontal calming can also lead to reduced speed limits.

And reducing average speed is important because it makes the street more safe while also limiting how fast much the occasional reckless driver may travel.  Horizontal calming, and the resulting reduced speed limits, are key elements of the European Twenty is Plenty movement, which argues that 20 mph is an appropriate speed for most neighborhoods, and the parallel Vision Zero movement, which targets zero pedestrian death through numerous measures including lower vehicle speeds.  Vision Zero has been implemented in New York City with a widespread speed limit of 25 mph.

The Twenty is Plenty and Vision Zero movements grew out of the fact that we’ve consistently built streets that can be comfortably driven at speeds in excess of the speeds for which we had hoped.  Perhaps it’s my sense of humor, but I find it funny that one of the biggest problems encountered during a recent cross-country driverless car experiment was the frustration of other drivers that the driverless car wouldn’t exceed the posted speed limit.

Also, slower speeds have multiple benefits, from reduced stopping distances to increased awareness of other street users, as described in this article from Minneapolis about the benefits of reducing travel speed by just ten mph.

If we want safer streets, we need slower travel speeds.  And slower travel speeds don’t need speed bumps when bulb-outs and striping will work just fine.

Policing: Policing can be a valid strategy to reduce traffic speeds, but it’s expensive and its effectiveness often has a limited duration.  The sight of a cruiser parked at the curb with an officer observing traffic or of a motorist awaiting a ticket will slow traffic that day and maybe for a couple of days afterward, but speeds will soon return to prior levels.

Most of us have probably observed this phenomenon on freeways where the sight of a police cruiser causes the average speed of the car pack to drop from 75 mph to 65, only to return to 75 within a few miles.

Policing is a bandage on streets that weren’t designed consistent with the intended travel speeds.

Street Uses: Lastly, I want to visit the comment that streets were made for cars.  It’s a particularly ironic, and incorrect, comment in my neighborhood.

I don’t know when the nearby streets were first paved.  But I know that my neighbor’s home was built in 1918, with my home following two years later.  And I don’t think either home was among the first in the neighborhood.

It seems likely that the streets were first laid out in 1910 or before.  And in 1910, the predominant street users would have been adults walking or bicycling to work or to errands, children playing, and horse-drawn carts delivering milk or hauling agricultural products to market.   If there were any cars, they were likely putt-putting along under a speed limit of 10 mph or less.

It wasn’t until the 1930s that automotive industry campaigned to dedicate streets primarily to cars, including inventing the word jaywalking.

I’m not arguing that cars should be excluded from streets.  They serve a legitimate purpose and make our lives more convenient.  But the balance between cars and other possible users of the street has been renegotiated in the past.  There would be nothing wrong with another renegotiation, including one that slows cars to make the street friendlier for all.

I understand that most neighborhood discussions about traffic speeds quickly turn to speed bumps and police.  But there is a wealth of other strategies that work better and create better communities.  We only need to become more knowledgeable.

Next time, I’ll write about the basic stuff of streets, asphalt.  Petaluma recently lost a sustained battle against a new asphalt plant in town.  Years ago, I weighed in on that controversy.  Now, I want to revisit my old words and to note that others are supporting a related position that I took at the time.


In recent months, Petaluma Urban Chat has become consumed with the question of the Fairgrounds, resulting in extra meetings and changing locations.  But, our standard meeting time and place remained the second Tuesday of the month, 5:30pm, at the Aqus Café.  This month, that date will fall on April 14th. Let’s gather at Aqus, 2nd and H Streets in Petaluma for an update on the Fairgrounds effort and to discuss future Urban Chat topics.  All are welcome.

As always, your questions or comments will be appreciated.  Please comment below or email me.  And thanks for reading. - Dave Alden (

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