Back when railways were first invented, they used to avoid
this by simple systems such as an Iron Ring or other
:
Driving without the token was an offence, perhaps a sacking
or criminal offence ?
I commented to LK (another systems engineer): Another
single track, head on train collision, that a couple of smart
phones with GPS & SIM for SMS [to optional server] could
have stopped!
Replies from LK:
Aircraft have had TCAS (Traffic collision avoidance
system) for years, almost the same system could be
used.
I wouldn't rely on the mobile network, 13, 27 or 41 MHz
license free bands would be suitable. Works around corners
at those frequencies, easily reach a mile, simply listen
and blind transmit when there's a gap in received
transmissions, but use a pseudo random delay before
transmission, to reduce collisions. Maybe an argument could
be made for 2.4GHz semi directional transmissions from the
front and rear of each train in order to provide more
frequent transmissions of data.
Amount of data transmitted would be minimal, but it
would be nice to transmit as often as possible. Each line
would require an ID, say 6 digit, single or 2 digit
direction, 3 digit speed, latitude and longitude (not sure
how many bytes would be required for these).
Would not conform to safety critical issues, but all
that is supposed to exist already yet we still see
accidents! It would add another level of safety over and
above existing human over-rideable systems.
I wonder whether a passive radar based emergency brake
system would also be useful. It would need to have GPS and
a memorised map to know where are the corners and in areas
with points, the points states would be useful. Otherwise
false braking could occur near points. This would ideally
be required on my other concept. L
