: >Hi,
: >I was wondering how most automated level crossings work, ie what trigers
: >the lights to start flashing (and for that matter, signals)? Is it, as I've
This brings up smething that's been fascinating me. New Lynn here in
Auckland looks like this (single track):
Up Sig L/C Down sig
<| |>
| | | |________|
Waitakere<------------------------------------------------------->Auckland
| | Station Platform
During the day there is a DMU suburban service. At night there is a
reasonably heavy freight service.
When the freight service runs at night the Level crossing seems to be
worked by track circuits in the usual way. However the DMU service runs
somewhat differently.
A down DMU approaches the station and stops at the platform. At that point
the down signal is red and the LC barriers down. When the train is ready
to leave it sounds the horn, the barriers drop and the signal clears.
In the other direction, the up signal and the barriers seem to be
controlled by track circuit.
I presume that the signals (both 2 aspect) are only there to protect the
level crossing. If they were there to add a section and increase capacity
I would expect them to be at least 3 aspect since the rest of the signals
I've seen on the line are 4 aspect. The location is not a passing place.
I don't know where the signalling control centre is. but it's not within
earshot. and I couldn't see any CCTV cameras.
My questions are:
How does sounding the horn trigger the signal/Level crossing?
Does this mean that the DMU service and freights can't share the tracks at
the same time? The station is in a dip between two gradients so whichever
way the freights were travelling they'd be stopping against the grade then
starting against it again if they had to stop at the L/C.
-- Chris 'fufas' Grace Somewhere south of the equator and north of antarctica "The natives got a bit restless during the night, but they were driven off by a shrieking figure waving a whisky bottle." "Really? Who was it?" "You, Sir."