Monday, 21 October 2013

One-Two-One One-Three-Two

Not one to give up easily, the Mayor of Adelaide, Steven Yarwood, and Adelaide City Council were not prepared to accept all of the negativity and carping about the experimental Sturt Street bike land and after a lengthy period fo thorough consultation, have released plans for proper cycling infrastructure along Frome Road in the city. It actually looks really good. Here's hoping it spreads across the city.

Beginning at South Terrace, the plan is for a complete route all the way to North Terrace using protected bike lanes.

Predictably, the howls of protest did not take long to start and Mayor Yarwood to have to get on the defensive and ask everyone to simmer down a little.

The complaints you hear are predictable and the assumptions behind them generally mistaken. A common gripe comes from what is perceived to be removing space for cars, generally in the form of reducing the number of lanes.

The plan involves Frome Street being reduced from two to one lane, except at intersections where there will be a separate slip lane.

Is reducing the street to one lane really so bad and will it increase congestion? The concept of induced demand suggests no as does the fact that traffic often seems to behave like a liquid. It seems to flow quite well until it reaches a bottleneck of blockage and then you have tailbacks.

Starting at the southern end, Frome Street starts at Carrington Street. That street only has one lane in each direction:

Turning on to Frome Street, it suddenly switches to two lanes:

There is no reason for the change at all other than the fact that there is space for it. That then continues all the way down to the zoo where, because of space restrictions, it reduces back to one:

At certain times of day, that is where you get the bottleneck - exactly as you would expect.

Another bottleneck is at the intersection with North Terrace because of buses turning right. Once Frome Street is reduced to one lane and the bike lanes, there will still be plenty of space to allow for that and even space for buses to have their own lane:

You see this sort of thing all over the place. This is close to the intersection of Main North Road and Fitzroy Terrace - both of them busy and wide roads:

You can see that the single right turning lane turns into three just before the intersection. In fairness, I assume that is so that three short rows of traffic can get around the corner when the light is green to avoid a long tailback. Having said that, once it's around the corner, the traffic is taken the short distance to Prospect Road and then just after that, the three lanes reduce back to two - another bottleneck:

All that happens when a lane is split like that is that there is a mad dash to the front of the queue in each lane followed by ridiculous jossling to get in front once the light turns to green. It slows everyone down. You see it happening every day.

I cannot help thinking that traffic could flow more smoothly (if that is your goal) by avoiding bottlenecks like that. Slow the traffic down to increase road capacity. The new single lane Frome Street will be just fine with a 40 km/h speed limit - and it will be fine with one lane. Slower traffic travelling more smoothly is better for everyone:

You burn the least fuel, and thus pollute the least, when you drive at a slow speed, providing a steady flow of gas to the engine or, even better, coasting. The biggest cause of pollution is the traffic dance of constantly speeding up, slowing down, braking, and idling. In urban areas particularly, the faster the speed limit or the feel of the street, the more starting and stopping drivers do. When traffic speeds slow down overall, the flow becomes smoother, and the result is less pollution.

It is also of course a lot less stressful. I have heard that heart attacks are not all that comfortable so if we can avoid them, all the better.

Saturday, 5 October 2013

Neighbourhood traffic calming

While pondering bike lanes, where they should go, how separated they should be and how wide, it is easy to forget the things that can easily be done in your local neighbourhood to slow things down and drag residents out of their houses into the sunshine.

I think it is fairly well established that sticking 40 or 30km/h speed limit signs around the place is not that effective. People either ignore them or whinge about them. You change behaviour by changing the built environment. Traffic is slowed very easily by narrowing the street, removing the painted line in the middle of the road and by making it much harder to speed around corners. It amazes me that there are not more prangs involving cars at residential intersections. So often we see drivers take a right turn at speed and on the wrong side of the road. It is a matter of pure dumb luck that there is not someone coming the other way at that point. They are generally just a few metres back. Enough to make the driver swerve just a little but not quite enough of a scare to stop the practice.

Narrowing the road at intersections can serve a number of purposes. If you make the street narrow enough, only one vehicle at a time can get through. That certainly slows things down. Narrowing the street also makes it easier for pedestrians to cross - they don't have quite as far to walk. As part of the narrowing you can also send a clear signal by making the pavement continuous so that cars have to be driven across the pavement. You would think that would send a pretty clear signal about right of way.

Another positive about build-outs at intersections is that they can be turned into stormwater gardens. If the local council advertises well enough, there is generally a helpful neighbour who would be happy to adopt it and tend to the plants.

Doing the right thing on corners can not only bring the place alive but it can boost business. Here's a corner on Wright Street where the Jam Bistro is (go there for great food and coffee served by one of the best Baristas in town - Adam. He has no hair on his head but lots on his chin. Go figure):

There is space for nearly 20 people to sit out the front. A single car takes up the same space. How easy would it be to extend the pavement further out into the street (the same width as the parked cars) and free up all that space for more tables? You would double the number of patrons for the price of a single car parking space. The person parked there probably isn't buying coffee from Adam anyway. It would be no loss at all, only a gain - for the city and local business.

Montreal shows us how: