Even if a
neighborhood chooses to accept a lower speed limit, the realities of effecting
that change can be daunting.
In earlier
posts, I wrote that the joint use of public streets was reduced by
the advent of the automobile and that some people are pushing back by proposing
a maximum speed of 20 mph in all residential
neighborhoods. (Tying together my recent
threads on streets and parks, I’ll note that park use would likely improve under
a “Twenty is Plenty” policy. Parents may
be more willing to let children walk to a park if cars were well-behaved.)
Let’s assume
for a moment that a neighborhood unites behind the “Twenty is Plenty” concept
and wishes to reduce the speed limits on their streets. How should they proceed to implement the change? Most would probably assume that a petition to
the city council would be the right first step.
They’d be wrong.
Cities have a
surprisingly small role in setting speed limits. Instead, rules written in Sacramento are used
to set the speed limits, with only a small bit of local autonomy permitted. And those rules mandate that the speed limits
be established based on how fast we actually drive.
The process
is simple and objective. Vehicular
speeds are collected by radar when speed limit signs aren’t present. The speed limit is then set at the 85 percentile
of measured speeds.
Most people
are startled when they first learn this.
They’re shocked that speed limits are set by how fast we do drive, not
how fast we should be driving. But it’s
indicative of how well the automobile lobby has played the public policy game.
To be fair,
cities have a small bit of remaining authority.
A City Engineer can unilaterally reduce the speed limit if he believes
that there are traffic hazards not visible to the driver. But those reductions can be challenged in
court by a driver who feels wronged, so City Engineers are cautious in their
use.
Some may
have spotted a possible loophole in the speed limit process. They may be thinking, “What if we ask neighbors
to drive slowly while the speed data is being collected? The 85th percentile would be pushed downward
and our neighborhood would be safer.”
The idea
isn’t new. I recently learned of a North
Bay city that tried the trick. City
employees were recruited to slowly cruise through the speed check area. At first, the plan worked. A lower speed limit was established and the
police began enforcing it rigorously, with speeding tickets being written.
But as
happens with most conspiracies, someone blabbed. The tale got back to the traffic court judge
who was heartily displeased. The
collected traffic fines were returned, the speed limit was raised, and a round
of hand slaps was administered.
If we assume
that Sacramento isn’t about to change how speed limits are set, what other
options do we have? We can build streets
such that the comfort zone of driver is affected, with resulting lower speeds.
In recent
years, we’ve already begun seeing some of these driver comfort zone
modifications, which are collectively known as traffic calming strategies.
Calming strategies
are often categorized as horizontal or vertical. Horizontal modifications can include street
markings, such as center stripes or the City Repair intersection painting concepts
that were discussed last fall. Other
concepts include narrower streets and center medians. Even roundabouts can temper traffic speeds,
unlike stop signs which sometimes result in dashes between intersections.
Vertical
modifications can include speed bumps, speed humps, which are wider than speed
bumps and allow higher speeds, and speed tables, which are wider yet and usually
include crosswalks or other pedestrian accommodations. The new East Washington Plaza in Petaluma
makes extensive use of speed tables.
But there
are two problems with traffic calming strategies. First, they’re costly. When cities don’t have the funds to fix potholes,
street modifications to reduce speeds are likely out of fiscal reach. Second,
public safety agencies, fire, police, and ambulance, often push back.
This isn’t
to criticize public safety agencies, but for too long they held too much
influence over street geometry. Streets
were built with widths and turning radii such that emergency vehicles could
respond as quickly as possible, the street geometry encouraged higher driving
speeds thereby pushing up speed limits, and parents began keeping their
children inside because of concerns over pedestrian safety. In one of great ironies of urbanism and
vocabulary, public safety became the enemy of public health.
In recent
years, public safety agencies have been forced to negotiate emergency access
versus pedestrian safety, although not always happily. Within the past few days, a San Francisco
Supervisor and the San Francisco Fire Chief had a public contretemps over street widths in
new development.
The
balancing act between public safety and public health will hopefully continue. It’s another reminder of Jeff Speck’s
observation that cities should be designed by generalists who can find
reasonable balances between alternative goods, rather than by specialists who push
only their own agenda.
Even if
reducing traffic speeds in residential neighborhoods is a good idea, and I
think it is, the path to making those changes won’t be easy.
As always,
your questions or comments will be appreciated. Please comment below or email me. And thanks for reading. - Dave Alden (davealden53@comcast.net)
No comments:
Post a Comment