The original “T68” trams in Manchester were fitted with whistles derived from LMS steam locomotive hooters adapted to work on air and indirectly operated via an electro-pneumatic valve. They were often ineffective in the city centre, causing drivers to improperly switch the tram into off-street mode on-street in order to sound the screeching off-street horn. I used to hear that all day when I worked in an office near Piccadilly Gardens. The replacement “M5000” trams are fitted with a synthesised version which could easily be altered digitally to sound like a gong, though not necessarily a loud enough one (see below).
Gongs or bells have been traditional wordwide for nearly 200 years for trains or trams operating on-street, as seen in so many Westerns. Gongs/bells were a condition of doing without a man with a red flag walking in front of trains. The reason is urely scientific; a gong (or bell) is essentially a distinctively struck sound, a sound of impact, enabling it to penetrate semi-consciousness effectively. That’s also why bells are used in boxing matches. Nothing else works.
It is the gong sound’s sharp “attack”, as seen on an oscilloscope, that makes it so effective. Flue sounds such as whistles have a softer attack which doesn’t grab attention in the same way. Yet gongs are seen as friendly, possibly because of their subconscious association with happy events such as weddings.
The feeble synthesised “doorbells” fitted to, for example, Sheffield and Birmingham trams aren’t really proper tramway gongs. Tram drivers need to be provided with a “tool” which is effective in all conditions. That should be an electric, synethised or air gong which can sound single strokes or repeated strokes, gently or loudly. Such a gong sound can be controlled, for example, by a rocker button, forwards for single stroke, backwards for repeater, with velocity detection, as with an electronic piano, so that the faster the button is pressed down, the louder the gong rings.
But Metrolink drivers and the Manchester public have been denied that ever since a bunch of clueless contractors drank themselves silly in a pub 30 years ago. Now the powers-that-be can’t backpedal because they’d lose face, and we can’t have that can we.
The following links are relevant:
Metrolink whistle recording – Toot 1.m4a
Illustrating the background noise with which the audible warning of approach may have to compete (Pride Parade, Manchester); do either or both of the trams sound their whistles or not?: IMG_1077.MOV
The appalling racket made by the trams at Victoria station, sounding very much like the whistles:
Demonstrating the fitness-for-purpose traditional tramway gong in Oporto:
Sound of actual tram gong:
https://www.youtube.com/watch?v=MZaaWMLl5n0 – white noise
https://www.youtube.com/watch?v=4a-yGdxk3VY stupid cyclist