Fog and Level Crossings

[tsr]

After some digging I found my copy of "The Great Western Railway: 150 Glorious Years" which describes the GWR first installing a system with differing clear and warning in cab sounds in 1905. By December 1914 they had 180 miles and 90 locos equipped with this kit, with the addition that an unacknowledged siren would automatically admit air to the breakpipe and thus apply the break.

Like a lot of solutions from the first hundred or so years of widespread railway operation in Britain, the technology is relatively simple (often there is no pressing need for digital or complicated electronic equipment to be involved, even now), but it's the ease of use in applying safety procedures - and the universality of the system - that are the truly great bits. I love systems like this, because it clearly shows the best principles for designing safety equipment. With a bit of modification, systems like this can be built up into safe options for years. But anyway... happy rant over!

 

[IanXC]

Like a lot of solutions from the first hundred or so years of widespread railway operation in Britain, the technology is relatively simple (often there is no pressing need for digital or complicated electronic equipment to be involved, even now), but it's the ease of use in applying safety procedures - and the universality of the system - that are the truly great bits. I love systems like this, because it clearly shows the best principles for designing safety equipment. With a bit of modification, systems like this can be built up into safe options for years. But anyway... happy rant over!

Indeed, for those who've not seen it the system comprised of a track mounted ramp, electrically live when signal is clear and a plunger mounted underneath locomotive. When the plunger hit a dead ramp it would rise and allow air into a siren (and subsequently into the breakpipe), when the plunger hit a live ramp an electromagnet would close the air route into the siren and sound a bell. This of course has the failsafe that a failure of the ramp to energise will sound the siren.

 

[reb0118]

In those days there was a fog signalman by the track who put a detonator on the line if the signal was at danger, and removed it when it was cleared. A sort of manual AWS.

Dets are still known as fog signals to this day.

 

[Expression357]

For those that like it - here's the appropriate module of the Rule Book.

Rule Book: TS9