Wednesday 29 September 2010

Left on Red

Some coordination equilibriums are more efficient than others. Here in Kiwiland, we drive on the left-hand side of the road like the Brits and Japanese, which gives us very nice access to second-hand Japanese cars for which we'd otherwise need to compete with the Americans.

The odder road rule has been "Give way to the right". Now, this always makes sense in roundabouts where the equivalent is "give way to traffic inside the circle". Very sensible. But it's been applied more broadly. If two opposing cars want to turn onto the same side street, the one making the right-hand turn (crossing traffic) has the right of way.

Give way rule change

That saves minor amounts of money in that we don't have to have as many traffic lights with arrows on them for turning traffic, but means there's reasonably complex calculation required before making a left hand turn. Why? Because if another oncoming car can cut-off the fellow turning right, then you can turn. Sometimes, that other car will swerve to go around the turning car, sometimes it won't. The same calculation applies if you're making the right hand turn: will the car behind the left-hand turning car swerve out and cut you off, or wait behind the turning car in which case you have the right of way. Our Erskine visitors always find this the worst part of adjusting to NZ driving.

The "true but little known fact" is that the official rules also give right of way to right-turning vehicles from minor side streets over right-turning vehicles from the main street because the car on the minor street is to the right of the car on the major street. Unless, as I understand it, there's a stop line in front of the car on the minor street and no stop line in front of the car on the major street. Except that none of the lines have been repainted in a decade so you never really can tell. Fortunately, people are smarter than rules and have converged on the norm of "major street traffic has right of way over minor street traffic". Except, of course, for newcomers who expect the rules to be as written in the rulebook rather than learning them from established practice.

The government has proposed a rule change so we're more in line with international norms: folks turning left will have right of way over folks turning right. I like the move if it's accompanied by retrofitting of some turn arrows on otherwise difficult intersections.

But while we're considering changing the road rules, here's one that really really ought to be adopted at the same time. Allow left turns on red lights after stopping. Almost all of North America (not Montreal) allows right on red except in spots where it's specifically prohibited; New York reverses the default rule. There surely will be some places where heavy pedestrian traffic or obstructed views makes it unsafe; it oughtn't be hard to single out those few places for "No turn on red" signs. But the default rule ought to allow such turns.

Confession time: I made left turns on red for the first year I lived here 'till I figured out that it was banned and I could be ticketed. Now I only do it when feeling particularly nostalgic and nobody's looking.

US data suggests very few accidents from these turns relative to the efficiencies gained.

If we're changing the rules anyway, now's the time to change this one. Make it so!


  1. The best thing about add both rules, is the second means the left turning queue is shorter by the time the light turns green (due to all the sneaking) thus the turning right traffic has less to give way to.

    Also it makes turning right (which is riskier) more expensive, so people should learn new travel patterns to avoid those expensive (and risky) turns. Again freeing up the intersections faster.

    Oh happy days! (if it happens)

  2. @Simeon: There are indeed complementarities. Let's hope!

  3. I agree with you on the red light rule, I've experienced this is Australia, it is a great time-saver to be able to turn left on a red as long as the way is clear.

    As for changing the give way rule, aside from bringing us into line with international norms I don't fully understand the benefits. I admit I haven't sat down and analysed the consequences for all intersections, but thinking about my commute to work there don't seem to be many cases where his will make any significant difference. It seems, on the surface, that all it will achieve is to push the burden of having to wait to a different set of motorists, those in the middle of the road trying to turn right. I fail to see how having a queue of traffic waiting in the middle of the road makes any intersection safer, especially if there isn't a designated turning lane. Traffic behind them still have to veer around them, admittedly to the left of the road rather than towards the centre, or have to wait until the way is clear on narrow roads.

    Having said this, I have spent my entire driving 'career' using our existing rules, and haven't really experienced the other way of doing it for any length of time, so I may just be resistant to change.

    It does surprise me how passionate some people are towards the change. I've heard a lot of people saying things like "It's about bloody time we got rid of this ridiculous rule" and I have to confess I don't fully understand their vehemence. I have never had any trouble understanding and complying with giving way to the right, it seems perfectly reasonable to me, but maybe thats just because its what I'm used to.

  4. I think that this is a waste of time and money and it seems to be based on: oh the consensus is so and so lets follow it and look good. I also don't understand this "turn left after the red lights stop". sounds like nonsense to me

  5. I think the changes to the give way rule are aimed at reducing some of the ambiguity that exists around having to second guess other driver's actions as mentioned by Eric. Whilst traffic still has to veer around cars waiting to turn right, that veering will have no impact on determining who has right of way out of the two cars turning.

    Besides which, technically, if the road is too narrow to allow you to make a right turn without holding up traffic you're meant to pull to the left until the road is clear and then turn.

  6. @Anon Actually the turn left on a red light thing works very well. Essentially you treat it as a stop sign controlled intersection for the purposes of turning left. If the way is clear and it is safe to proceed you can make your left turn and go on your way, as long as your path doesn't take you across the centre line. It may sound a little odd to allow certain drivers to disobey the lights, but in reality it works quite nicely.

    @Duncan I see the point about veering cars etc. That does make some sense. There aren't, however, many drivers that actually do move to the left when making right turns on narrow roads. From my experience I'd say they would be in the minority. I'm not saying thats a reason not to change the rules, just highlighting that we aren't the most considerate drivers in the world :)

  7. your better off putting a signal instead. Much better leaving it up to people who are careless enough to abuse it