The correct English?

On a road sign tonight coming home it said this:

"Find alternate route".

Shouldn't it have said "find alternative route"?

Which one?

I would have said "find an alternative route" - but that's just me!

Indicator lights alternate between on and off. I have no idea what the sign means.

Yeah, that's what I thought. Alternate means to switch between two things hey?

Alternative means find another.

I would also have said "find an alternative route".

Incorrect English grammer, but cheaper to paint on a sign and enables you to use bigger letters and therefore makes the sign easier to read.

Easier to read, but far, far more difficult to understand.

Alternate route? You mean a route that is only there on Monday, Wednesday and Saturday?

It is incorrect because "alternate" has nothing to do with "alternatives" at all.
Alternate has to do with a repeating pattern and the action of changing between segments of a pattern.
(It is a verb)

Alternative indicates there are two or more options from which to choose one option...it is a noun.

So they sound similar but are actually 2 completely different words and are not interchangeable.

Incorrect? Yes. But, it was a road sign, so you have a matter of seconds to read it. When reading that very quickly (as you would when driving), it could easily be confused by some as being read as 'find alternative route', which is easy to understand. Or, the sign may not have been big enough for 2 extra letters?? ;)

Its correct English. In this use alternate is an adjective. Pronounced ol ter nit rather than ol ter Nate.

I agree it's correct as well.

I agree that it's correct and even padding it out I would say 'find an alternate route'.

No idea if it's correct or not, but I've seen it used this way before.
Not that that means it is correct :p

Even used in its adjective form, 'alternate' still would mean 'every other [road]' rather than 'a different [road]' so the usage in this case is indeed incorrect.

Actually it doesn't always mean that.
Alternate can also mean a choice of one or more. I will find the dictionary definitions I found when I'm not on iPhone.

Thanks guys. It was on one of those electronic road works signs so had been programmed in by someone.

My mistake Pandora - my fault for going on the first set of definitions I found! Alternate *can* be used as an adjective to mean 'substitute' 'used in place of' or 'second or further choice' (although these definitions do seem to be more common in American dictionaries).

In addition to the word on it's own, I found something pretty interesting (well, to me lol) on where the term 'alternate route' came from.

In the US, An alternate route is a route that branches off and then back on to the main/parent route, but not in order to bypass a town/place. There's a cool picture I might put on my fb and link back showing different kids of routes/roads

Awesome!

Even when used as an adjective, in correct English, this use would be incorrect.

The Oxford dictionary recognises that in "North American English" Alternate can be used in this way, but we are not American, and do not speak American English, nor is is "correct".