Sunday, December 2, 2012

Keep-left and keep-right rules: origins

Why some countries drive on the left and some others on the right?

I have always lived in countries with the keep-right rule, and if you look at the map below you'll see how in the majority of the world the keep-right rules applies (from wikipedia)!

Red: Drives on right
Blue: Drives on left

Accustomed to the keep-right rule, I have always found strange that some countries like UK, Ireland or Australia had the opposite convention. Well, as I learnt today, for some reasons it made and still makes more sense the keep-left rule.
Let's see why.

Everything started in the Middle Ages or probably even earlier in the Roman empire.
In those times (and partially still today...) roads were very safe, so meeting people coming the other way was something best done defensively. Indeed, by keeping the left side of the road, you could more easily protect yourself, by drawing your weapon (attached to the left side), with your right hand.
This is even more evident if you were riding a horse.
This makes sense, doesn't? Yes, it does but not everyone agrees on this explaination (read the reference #1 at the end of this post).

Obviously, the keep-left rule also makes sense when you meet a friend, because you can offer him more easily your right hand. Useless to say, all these considerations apply because most of the world population was and is right-handed. Sorry left-handed guys and girls... ;)

The origin of the switch happened in the US during the 18th century. Why?

According to (reference #2):

"What ended up happening to force the switch in the 18th century were teamsters in the United States, who would drive large wagons with a team of horses, as the name implies.  These wagons tended to dominate the road and force everybody else to abide by the rule of the road they were using.  Very importantly, in many of those old, large American wagons, they did not include a seat on the wagon for the driver.  Rather, the driver would typically sit on the rear left most horse, when the driver was right handed.  This allowed them to easily drive a whole team of horses with a lash in their right hand.
This then forced the issue of having oncoming traffic on your left as the drivers would want to make sure any part of their team or wagon didn’t collide with oncoming traffic.  When sitting on the rear left most horse, this was much easier to do when using a keep-right rule of the road."
The convention from US spread thorough Canada.

What about Europe?
Everything started in France.
France probably always drove on the right, and Napoleon required the countries he conquered to conform to French practice. Many other conquerors have done the same.  It tuned out that the conquered countries retained the French practice even when Napoleon was defeated. Among these, Germany that had great influence later on in spreading the keep-right rule.

The keep-right rule never applied in UK. Not only because it was never conquered by Napoleon but also because  the massive wagons in use in the US didn’t work well on narrow streets which were common in London and other English cities. Quite obviously the keep-right rule didn't apply in the British Empire either!

In sky and on oceans which rules apply?
The keep-right rule. Always.

#1 Very very interesting article about the keep-right and keep-left rules, probably the most exhaustive available on the web.

#2 You can spend hours on this website!

#3 Another reference on the subject

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