Ryan Cousineau <[email hidden]> wrote
Quoted message said:1) gives cars and cyclists alike a clear demarcation where
the cyclists know the cars almost certainly won't enter
their path and the cars know vice versa.
But cars do enter the bike lane at intersections, and
cyclists must leave the bike lane at intersections. The
sooner these lateral movements on intersection approach
occur, the less likely road users are to surprise or confuse
one antother. But the stripes tend to inhibit proper
destination positioning.
Quoted message said:This is a great confidence booster for cyclists not yet
ready for the exhiliration of feeling a car judge the gap
_perfectly_, and not knock them off their bike with their
mirror by a couple of inches.
The stripe doesn't increase the distance at which drivers
pass cyclists. The usable pavement width is what determines
how far over drivers can and do move when overtaking.
However, when the bike lane collects debris, cyclists who
stay out of it now have less usable pavement to share with
motorists. And I think it's nasty to put a segregation
stripe right next to where experienced cyclists will be
putting their tires - that provides them no wiggle room.
I've been cycling in travel lanes that are 16' to 20' wide
for years. I've never been passed at uncomfortable distance
on these roads. Our city police crash reports show no
overtaking collisions involving cyclists on roads with
lanes wider than 12 feet for as many years as data has been
kept. But last year the city started dividing the 16'+
lanes into a bike lane and a defacto car lane, and that's
when the problems (debris, close passes, harassment of
cyclists) started.
Quoted message said:2) by narrowing the roadway, it has a natural cautioning
and slowing effect on the cars. Because they perceive
that they can't just wander from ditch to median now,
the drivers stay between the lines.
There is substantial empirical data showing otherwise, that
the stripes alone don't slow traffic. But drivers do slow
down when passing cyclists, compared to where there are no
cyclists. Drivers tend to slow down more adn provide more
space when passing cyclists in wide outside lanes than
where there are bike lanes striped in the same total
pavement width.
Most of the often-quoted rhetoric in favor of bike lane
stripes compares apples to oranges, i.e. it compares not-as-
wide lanes on busy high-speed thoroughfares to really wide
bike lane/travel lane combinations on quieter 2-lane
roads, or it compares the speeds on one road with one lane
design to the speeds on a different type of road with a
different lane design. The best approach for scientific
comparison is to add a stripe to a 16'+ outside lane and
compare before/after data. When this is done to a typical
street, it turns out that the motor vehicle speeds don't
decrease (sometimes they increase), more debris
accumulates where cyclists ride, and there is no
improvement in cyclist safety.
I think that on really high speed highways with very few
junctions it is possible that the stripe may have net
benefits, but in general, operational conditions are
primarily determined by total pavement width. The
stripes are, at best, a waste of money and effort on
ordinary streets.
-Steve Goodridge
