I have encountered the following usages of 叉 and 岔 when dealing with forked roads:
叉路口
交叉路口
叉路
三叉路口
三岔路口
四岔路口
岔路口
Is there any rhyme or reason to when to use 叉 vs. 岔? Is one more correct than the other? or only in certain usages?
Based on a google image search, it seems like 岔路 is used on road signage more often than 叉路.
There's a similar question here:
https://zhidao.baidu.com/question/326153419.html
that asks:
岔路口 叉路口有什么区别
the answer reads:
岔路口有方向概念，也即你面朝的方向有两条以上的分岔路；叉路口（一般不这样叫）一般称为交叉路口，指两条以上的路相互交叉。
岔 = forked (road) like this:
the road splits in front of you, like crossroads.
叉 = intersect like this:
like a junction or an intersection.
Translating the word “forked road” is something interesting!
First, let’s go and look the English word “fork”. In Oxford Dictionary of English, it means “an implement with two or more prongs used for lifting food to the mouth or holding it when cutting” or “the point where something, especially a road or river, divides into two parts”.
And “forked” means “having a divided or pronged end or branches; bifurcated”.
Second, the character 叉（chā） doesn’t mean a implement originally. It means “crossing fingers”. In ancient etiquettes, 叉手 is not the way that western people crossing fingers but actually folding one hand onto the other hand. And it’s expanded meaning is “cross”.
By the way, the implement so-called 叉 might not be the original production in Chinese agricultural history. Because we had our own. Something like “耒, 耜, 耒耜, 铲, 锛”. Only “耒” had been described as “formed like a fork” by later generations. So that 叉 might be imported along some road on the western and northern grasslands of China. How about the ancient Chinese fork-like implement using in fishing? I have no idea.
岔（chà）specifically indicates “the point where something, especially a road or river, divides into two parts”. 岔 is taken about mountain as far as 汊（chà）is about river. While you see, 叉 is taken the meaning of “cross” in 汊.
岔, a bifurcated(分) mountain(山). 汊, a crossed(叉) river(氵).
（明）方以智《通雅·諺原》：「山歧曰岔，水歧曰汊。」
Technically, it should be written as 岔路(口), and 交叉路(口).
Here’s one more thing, we speak fēn chàr but mostly write it as 分叉(儿) because it’s easy to write but weird to pronounce as fēn chār.
