Wigwags? Defective ones? What is CRT talking about?

Alert from Canal and River Trust received today:

Sheffield and South Yorkshire Navigation

Barnby Dun

Monday 25 March 2013 - Wednesday 27 March 2013
Urgent works are required to enable safe passage through the bridge. This will involve the replacement of defective wigwags which will require the canal to be out of operation during the below times. On the 27th March, most of the work should have been completed, so there may just be a short delay whilst waiting to go through the bridge. We are working with the contractors to minimise disruption. Please ring the number below for latest updates.

The work will be carried out work between 8am-5pm daily. There will be no passage through the bridge during these times

Enquiries: 0303 0404040

This is the second time in as many weeks that I've been presented with a word that's new to me.

I looked up "wigwag" in my dictionary. It defines it as (v.i.) to twist about: to signal by means of flags; (n.) the act of wigwagging: a level crossing signal which gives its indication, with or without a red light, by swinging about a fixed axis (etc.)

Indications from Wikipedia are that wigwags are American signals of various types, found on the railway and in cars and lorries. (Or railroads, automobiles and trucks.) Oh, and a Wigwag is the Canadian version of the Curly Wurly bar (bet you didn't know that!)

I had never heard of a wigwag in any context, let alone a boating one, but they must exist as they're on the SSYN. Except that they're defective. Perhaps they only wig. Or, maybe, they only wag. Or - horror of horrors - could it be that they neither wig nor wag?

Am I alone in my ignorance of canal wigwags? Do you know what they are? What do they look like?


Yes, this is a railway signal. It is not, as far as I am aware, a wigwag.


[And the other new word: frit. It was in the Times. Thankfully, on Saturday, there was an explanation: apparently it's a contraction of "frightened".]