In article ,
Tim S writes:
Do you remember when traffic lights had this sort of setup, with two hoses
set into the road?

They were called road pad detectors.

Originally they used a pair of sprung steel plates held apart along
the edge, which deform and make contact with vehicle weight (but
supposedly, not by jumping on it). A twin version allowed detecting
direction of traffic, but was often used because when one unit broke,
the controller could be connected to the other one until they could
be replaced, which was required on a routine basis.

There were a number of attempts by the likes of GEC and probably
Plessey too to come up with longer lasting inserts for the iron
holders, and I did see pressure tubes.

Inductive loops have taken over now of course, and they work with
cyclists too.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]