Drivers “slow down when they are afraid they might damage their car”

COMMENT & ANALYSIS: Drivers “slow down when they are afraid they might damage their car” — this reasoning explains why the reaction to some street changes made since the start of the pandemic has been so strong.

Dice Oh, a member of People Friendly Stamford, made this key point in tweet: “One thing traffic engineers need to understand is that drivers do not slow down because of warning signs or posted speed limits. They slow down when they are afraid they might damage their car.”

“What can create this necessary fear (aka “traffic-calming”)? Narrow lanes, which create the possibility of striking another vehicle. Pedestrian islands and curb bump-outs. Bollards and planters at intersections. Tight curb radiuses. Speed bumps,” he said.

Oh added: “Things that DO NOT instil fear in drivers: floppy plastic flexposts. Signs that say “share the road.” Painted bike lanes. Sharrows.”

We usually don’t centre analysis articles on points from randomers in different countries, but it’s a brilliant point. And we can see how the thinking of it can be applied here in Ireland. Take the controversial concrete plinth in Cork back in 2014, or, more recently, the Griffith Avenue project in Dublin.

The Griffith Avenue scheme could be a lot better and that would make it easier for more people to defend it, but one of the reasons reason there’s been such a backlash is the fear of hitting a parked car or plastic bollards (some people don’t even like hitting them).

The project has not practically taken much space from cars. There’s mostly the same number of car lanes and there’s a lot of parking being provided as park of the scheme. It’s just that the ultra-wide traffic lanes have been narrowed by placing the cycle track inside car parking. Or, in other words, pushing the location of the car parking, as one angry Facebook user described it, “into the middle of the road” (translation: anywhere not right beside the kerb).

Here’s an example of car parking out in what once was a very wide lane. Note, there’s still space to get a bus or truck pass this with ease:

On a different section of the project, this is highly unlikely to slow motorists down enough  — buffer space protects motorists from feeling they are too close to the concrete, and there are two general traffic lanes in the opposite direction. This is designing for speed.

Again, the Griffith Avenue scheme is far from perfect. But it’s an interesting case in terms of how different parts of it function and why motorists are complaining.

Similar can be said about the narrowing of junctions in different locations and the installation of (narrow) cycle lanes on Melbourn Road near the Munster Technological University. Narrowing which slows motorists down is strongly opposed using over-the-top reactions which make little sense when you look at what’s on the ground.


  1. A Big problem is motorists tailgating cyclists on roundabouts. We make one mistake or our bikes give us grief and no room to…survive. They seem to think we have a trottle on our bikes and can just pull away from them.


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