Posted by: Gregory | May 9, 2015

Those pesky roads

There was a story run in the DomPost last week about cyclists coming off their bikes in Pukeahu National War Memorial Park because of poor visibility of the kerbs. It’s a bit of a design flaw that’s only coming to light now that real people are interacting with the park. I’m sure we’ll find more issues as we go.

“It’s supposed to be a cycling and walking-friendly place, so you don’t expect to come across something like that,” group committee member Alastair Smith said.

He first noticed the low kerbs when he crashed off his bike last November, before the Pukeahu National War Memorial Park was finished. He was riding on the north side of the road through thepark, and had to move around a parked car.

He did not see the kerb, clipped it with his wheel and came off, injuring only his pride.

The problems stemmed from the kerbs being only 50 millimetres high, and being hard to distinguish from the road and cobbles, especially after rain.

As I was walking through the park today, I was drawn to the fact that the roads have been given an inconsistent treatment. Cobbles are featured on Buckle Street up to the memorial access and smooth asphalt on the connector between Tory and Tasman.

I happen to have a serious issue with the traffic speeds that can be obtained on the through road, and it’s part of the same problem as the kerbs. With only 50mm kerbs, the raised table isn’t enough of a feature to force fast traffic to slow. The narrow road is meant to encourage lower speeds, but I’ve seen a few vehicles cutting though in the range of 50km/h.

Photo credit: Memorial Park Alliance

Photo credit: Memorial Park Alliance

The roads highlights in red are normal asphalt, yellow are raised tables and blue are cobblestones. I’ve marked up the photo from memory, so I may have gotten some details wrong. The cobblestones do a good job of reminding motorists that they are in a low speed place. With the 50mm kerbs, the raised table on the link road is pretty useless. This is contrary to the plan put forward by NZTA (PDF):

NZTA Memorial Park Local Road Performance

What should have happened was for the Tory/Tasman link to be cobblestone. I’d expect that the current raised table may need to be left as-is to allow for people with disabilities requiring a smooth pedestrian surface to cross safely.

Returning to the issue of kerb visibility, the DomPost article had indicated that even with cobblestones, the kerb wasn’t clear. While this is quite true, the implications of the surface texture can be quickly learned. I doubt many people would make the same mistake twice.wpid-wp-1431163731890.jpg

In the above photo, there’s no difference in surface texture between the footpath and the road. A cyclist would very easily miss the visual cue and not notice the 50mm drop.

wpid-wp-1431163739753.jpg

This photo shows a clear delineation between footpath and road. It would be hard to not notice the boundary between the two.

Interestingly, the west end of Buckle St is paved in asphalt instead of cobblestone. Along that section, which I failed to photograph, they’ve added a physical barrier between the footpath and the road as a trial measure. I’m willing to bet that if the roads were consistently paved, this wouldn’t be as much of an issue.

Alliance manager Duncan Kenderdine said the small kerb enhanced the open feel of the park, but accepted that problems had been raised about it.

The alliance was aware the white line solution was not sufficient. “We are now reviewing the options around physical changes to reduce people meandering across the kerb, or ways of levelling the kerb by cambering or adjusting levels beside it.”

There were plans to talk to those who had been affected about what the best solution might be, he said.

I wouldn’t suggest that putting cobblestones along the roads in a consistent fashion would solve all the problems with the park, but it should provide necessary visual cues while slowing traffic.

That just leaves us with things like this:

wpid-wp-1431164704248.jpg

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Responses

  1. I think kerbs are often put in where they aren’t needed at all, and they create problems for pedestrians as well. The traditional aim of a kerb is to channel water into a gutter, and get it to the sea (or stream) as rapidly as possible, carrying all the pollution with it. It is now recognised that this is not optimal in terms of stream/coastal health, cost, etc. Memorial Park has a somewhat more modern approach to stormwater management, that uses rain gardens. In those sorts of developments I would favour using the raingarden to separate pedestrian and road space, and just having a gentle slope to move water off the hard surfaces into the soakage areas, with no kerbs.

    • On my Walk2Work chat with Stu, he was pointing out problems with the gardens at the memorial and spoke about the mistakes at Lower Cuba St. We need more expertise in water management in urban areas to get these things right.


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