Thursday 19 July 2012

Sharks Teeth.

A clear understanding of who has right of way at a junction is very important for safety because it removes conflict and confusion between road users. If you want a system that does not reward more and more aggressive road use (Might is Right) then you need clear rules signs and markings. Rules are complex to change and no one knows them, signs are expensive and often ignored but what about road markings.

IMHO Sharks teeth are a very clear indicator and this technique also has some professional investigation data to back up their effectiveness.

"An underlying investigation showed how road users best understand who has priority

1) by the so-called ‘shark teeth’ markings on the ground (which are more clear than traffic signs);
2) by having the color of the cycle path continue across the drive way of motorized traffic."


This is really easy to understand and should be used to reinforce the signs and rules that have legal authority but are not always as immediately clear as the symbol on the road. The concept is very simple: If the triangle points at you you have to give way at its flat top side.

Here is an correct implementation in Burgenland (Austria) at a cross road.

Here is a Dutch implementation at roundabout where they have unbundled the cycle path conflict from the roundabout and provided a stacking space.  The cycles have priority so this leads to 2 give ways for cars approaching the roundabout and one exiting.

This should be really hard to get wrong but in Vienna the quality of the implementation is often very poor.. Here are 3 examples of shark teeth implementations where this basic easy to understand concept has been messed up.

Shark 1 = Teeth not on junction give way line, so you have to give way before to pedestrians?

Shark 2 = Teeth upside down or you are supposed to give way after the junction?

Shark 3 = Teeth on both the 2 way cycle path (teeth one way only) and road, so no idea what this means.

Surely this is something that should be really easy to get right. It is not a question of money, space, priorities or politics it is just a question of quality. The rights of way rules are complex and make no sense, and are understood and interpreted differently by each road user. Sharks teeth could fix this easily with a solution that:
- works,
- is cheap,
- is very easy to understand,
- can be implemented everywhere,
- has establish use and data to back up its effectiveness.

Update Sep 3013:
I notice Sharks Teeth more an more when I visit neighboring Italy and Slovakia. They implement them properly but Vienna is still struggling with the concept.


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