In 2009,the country of Samoa prohibited the sale of alcohol for three days to keep people safe while the island nation switched from driving on the right side of the road to driving on the left.The switch was so Samoans could get cheap "hand-me-down"cars from nearby left-side driving New Zealand and Australia.But Samoans weren't too pleased,since most of the cars they owned were designed to drive on the right.

2009年 萨摩亚禁止酒精饮料售卖三日 为了在这个岛国从靠右行车转为靠左行车期间 保证人们的安全。这样做的原因是 萨摩亚人可以从附近靠左行驶的 澳大利亚和新西兰买到便宜的二手车。但是萨摩亚人也不是很高兴，因为他们自己的车都是为靠右行驶设计的。

In fact,2 out of 3 earthlings drive on the right.But why?...There aren't clear and obvious reasons to choose one side over the other,so the origin of driving conventions is a perfect opportunity for the mathematics of game theory and symmetry breaking.Or we can just look at historical evidence.Today's rules evolved from"driving"livestock and carts on the earliest roads.

实际上 三个地球人当中就是两个是靠右行驶的。但是 为什么呢?对于选择行车方向的偏好 没有清晰而明显的原因，所以说 这种习惯的起源对于数学上的 博弈论和对称性破缺而言 是一个完美的机会。或者我们可以看看历史上的证据。今天的规则 是从在古道上“驾驶”牲畜和马车的规则演变而来。

Archaeologists view deeper grooves on the left lane leaving an ancient Roman quarry in England as evidence for left-side traffic,since departing wagons would've had heavier loads.And it's possible that this left side convention was in place so right-handed soldiers and knights could draw their weapons more quickly against passing enemies.

考古学家将英格兰一个古罗马时期的采石场的文物上 左侧车道凹陷更深的现象作为靠左行驶的证据，因为出场的运货马车会装更重的东西。而且 靠左的惯例可能是适当的 因此 偏用右手的士兵和骑士们 能快速抽出自己的武器 迎击经过的敌人。

Whatever the reason,keeping to the left was eventually made into law in England in 1835.And today,most people who drive on the left side live in countries,like India,South Africa,and Australia,which were once British colonies.But that doesn't explain why the rest of the world drives on the right.Some claim that following the French Revolution,drivers there switched to the right to reject the practices of their overthrown aristocracy,but others suggest the French drove on the right all along.

不论什么原因 靠左行驶的规则 最终在1835年被英格兰以法律上形式确定下来。时至今日 大多数有靠左行驶习惯的人们的所在地，像印度 南非 澳大利亚 都是英国曾经的殖民地。但是 那不能解释为什么世界其他地方靠右行驶。有些人声称 在法国大革命之后，那儿的驾驶员们转成了靠右行驶 以抵制日贵族的惯例，但其他人说 法国人从来都是靠右行驶。

Regardless,driving on the right side of the road did spread across much of Europe when Napoleon(and later Hitler) imposed their national driving rules on conquered territory.And other countries voluntarily switched to the right to align with their neighbors,like Sweden in 1967,or to veer away from their colonial pasts,like Nigeria and Ghana in the 1970s.

无论如何 靠右行驶的习惯 在拿破仑(而后希特勒)将此强加到被征服领土之后 确实在欧洲大部分地区被推广开来。其他的国家自愿改为右行 就像瑞典1967年那样 以向它们邻国看齐，或是为了远离他们的殖民史，就像在七十年代的尼日利亚和加纳那样。

And in the US? Well,America owes its right-sided habit,in part,to the carts and postilion wagons of its early days.Driving either from the ground or from horseback,right-handed men preferred to walk or ride on the left side of the horses,so they could control the animals with their right hand.As a result,they drove their wagons to the right in order to be seated near the center of the road,to see and steer clear of oncoming traffic.

那美国呢 美国靠右行车 在某种程度上是因为，美国早期的左驭马的马车。不论是在地上还是马背上，右撇子喜欢在马的左边行走或骑行 这样他们就可以用右手驾驭牲畜。因此 他们会靠右行车 使得座位靠近路中央，以便于看清和避开迎面而来的车辆.

And that's ultimately the point of driving laws:to keep us safe from the high-speed,two-ton metal projectiles we call cars.

从根本上来说 这就是交通法规的要义 保证我们在高速行驶的 两吨重的 拋体一般的汽车中的安全。