Comments on: ‘Portion Distortion’ and the American Road

By: Alan

Alan — Sun, 19 Apr 2009 21:58:37 +0000

Pittsburgh, too, has very narrow streets, with much of it being cleverly jammed onto hillsides and into valleys. I definitely see cars pulling to the side to let others pass on a regular basis on the side streets.

By: Kelley

Kelley — Sun, 19 Apr 2009 21:51:09 +0000

Good news: the road diet is on its way!

http://www.streetsblog.org/2009/04/17/two-way-protected-bike-path-sails-through-cb6-committee/

By: Rational Plan

Rational Plan — Sun, 19 Apr 2009 15:31:36 +0000

The link between speed cameras and accident prevention has proved controversial in the UK. Mainly because accidents had started to decline long before their wide spread introduction and and have now that accident levels are not reducing any more despite the massive increase in camera fines. Partly this is because the increase in cameras has seen a dramatic fall in traffic police patrols, corresponding with an increase in accidents from run red lights and the increase in accidents of people who have no licence and are therefore uninsured.

A much bigger roll in the reduction in accidents in the UK is use of local road building funds primarily for road safety and junction redesign. Each council has a rolling target of accident reduction and it has to outline a plan how is it going to do it. For example the council where I live has just designated a neighbourhood near me a 20 mph zone. The old speed bumps were replaced, with humps that slowed cars but not buses, new speed tables plus junction narrowings. It is much more natural to drive at a slower speed. It is rare these days to find a residential road that is not subject to built in speed restrictions.

By: anonymouse

anonymouse — Fri, 17 Apr 2009 20:43:13 +0000

azbikelaw: in this particular case, there are no intersections because the bike lane would run along the park. Almost all the intersections on Prospect Park West are T-intersections because of the park, and the bike lane will probably be on the park side.

By: azbikelaw

azbikelaw — Thu, 16 Apr 2009 20:33:51 +0000

Tom,
I, too, would be interested in the Britian - speed camera vs. safety linkage.
In your book, you said something about how over the 1990’s british safety stats improved markedly (and sort of implied it was caused by the cameras). I didn’t see any footnotes for that but maybe i missed it. Anyways I think that would be a great topic for fleshing out.

There was a WSJ op-ed today pooh-poohing the notion of cameras causing a safety improvement. His comment on Britain was that “Britain has gone furthest in using cameras for comprehensive auto surveillance”, and NOTHING about safety !? see no evil, hear no evil , speak no evil.
http://azbikelaw.org/blog/more-photo-enforcement-in-the-wsj/

By: azbikelaw

azbikelaw — Thu, 16 Apr 2009 20:17:38 +0000

“A separated bike lane would be a great place to start — and would reduce the frequent cases of cyclists using the adjacent sidewalk”

I’m not sure what is meant by separated, but unless the (usually many, many) intersections can be somehow managed, these sorts of bike paths tend to have worse safety problems.

In other words, what you gain in reducing side-swipe and rear-end collisions are more that offset by an increase in turning/crossing collisions. (the separation tends to take cyclists out of the line-of-sight of motorists… out of sight out of mind!).

Being struck from behind, particularly in an urban (versus rural) environment and with a properly lighted cyclist, is a relatively rare mode of collision. This is hard for many to accept; but it has always and repeatedly been proven true, see e.g. Cross and Fisher
http://azbikelaw.org/blog/cross-and-fisher-1977/

By: Eric McClure

Eric McClure — Wed, 15 Apr 2009 17:26:00 +0000

Tom, thanks for posting about and linking to our video.

You and Brian Wansink are exactly right about excess road capacity and its inducement to speeding, something that was borne out in a road-test experiment.

We conducted a road test under controlled conditions to see how long it takes to drive (at the legal speed limit) from Union Street to 15th Street via both Prospect Park West and 6th Avenue, and from 15th Street to Union Street via 8th Avenue and 6th Avenue, in order to compare these one-way avenues with a neighborhood two-way avenue. We conducted the test at night to control for traffic volume (we were able to travel unimpeded by other vehicles); we made sure we started from a red light as the first vehicle each time; and we accelerated normally and used cruise control in order to maintain the 30-mile-per-hour speed limit when not braking for a red traffic light. The southbound trip took exactly two minutes and 57 seconds on both Prospect Park West and 6th Avenue. The northbound trip took three minutes and 20 seconds on 8th Avenue, and three minutes and 40 seconds on 6th Avenue. We repeated the drives in order to make sure conditions were consistent.

What can’t be quantified, but was clearly something we experienced, was that it felt like we were poking along while maintaining the speed limit on three-lane, one-way Prospect Park West, and conversely, it felt like we were speeding recklessly while driving at the speed limit on two-lane, two-way Sixth Avenue.

It was clear confirmation that street design and capacity plays a large role when it comes to speeding.

Keep up your great work!

By: Cheryl

Cheryl — Wed, 15 Apr 2009 16:39:58 +0000

It should be considered a product defect to manufacture cars which can speed. Since we can’t depend on drivers to drive safely in cars built for speed, perhaps cars which CAN’T speed are the answer - smart roads and cars which share info and prevent cars from accelerating over the speed limit. I know - overkill of technology - but failsafe. Do the speed cameras in Britain improve road safety? I’ve read that they don’t, but don’t really trust the source.

By: Dave

Dave — Wed, 15 Apr 2009 16:08:48 +0000

This is something I’ve thought a lot about. Living in Portland, Oregon, there are plenty of very narrow streets where, especially if there are cars parked on the side, one person has to pull over to let another person by. This keeps speeds of traffic often down even below 20mph - of course there are also main roads where there is nothing to stop a car from going 55mph except occasional stoplights (speed limits are very rarely enforced anywhere in the city). Any guesses where there are more accidents?

In thinking a lot about infrastructure both here and in the average European city, I think density plays a huge role. In Amsterdam, for instance, the density of people in the city simply means that a person cannot drive 55mph safely in the city, there isn’t room for roads that would support that.

In Vilnius, Lithuania, I felt very safe as a pedestrian, because streets were small, often cobbled, and therefore traffic speeds were pretty moderate within the city (of course, there are always some exceptions). Most people used public transit because it went literally everywhere, and was much cheaper than owning/driving a car.

From personal experience, I would agree with the assertion that the faster you go, the harder it is to judge how fast you’re moving. Even in our 1974 VW Beetle, the feeling of going 70mph is not proportionately different than going 35mph - not to mention in cars that are made for going fast. You can be going 100mph and have it feel like you’re just cruising along.

By: Jack

Jack — Wed, 15 Apr 2009 14:07:30 +0000

This video is not surprising to me at all. I witness speeding cars (usually 20 mph over 30 mph posted) and red light runners daily, all in front of a police substation. Every intersection around our neighborhood has the same problems, but worse. Maybe I should get one of those cameras too.

No doubt our eyes are bigger than our stomachs and our driving habits have gotten worse with the growth in convenience foods. Until we have effective and fair law enforcement, our streets will remain dangerous. I agree, “it is much easier to change a person’s environment than to change their thinking”.