Traffic on all
four networks is controlled from one central
location at Pleystowe mill. The four traffic
officers (TO) on duty sit in one common soundproof
room with a traffic supervisor. Each TO has a
console with a schematic of his rail network
projected onto a screen on the wall in front of him.
This screen, known as the Electronic Mimic Board, is
a computer programme that has some basic rules of
train control built in. The following is a very
simplified version of how trains are controlled.
Each train has a head and tail icon which allows the
TO to move trains around the network and display
what section of track each train occupies. When the
head of a train is cleared into the next clear
section, the traffic officer simply picks up the
head icon with the computer mouse and drops it on
the node where he is clearing the train to. If this
section is unoccupied, a transaction number is
generated which is issued to the train crew as their
authority to proceed. The train crew repeats back
the transaction number and the limit of the
authority for confirmation by the TO that they have
received and understood their authority. If the
track section is occupied, the head icon can not be
placed on the track. The programme will reject the
movement, return the icon to where it came from and
not issue a transaction number. The tail icon
remains at the other end of the trains limit to
ensure no following train can enter the occupied
section until the preceding train has cleared it.
A TO station also has three computer screens for
the following tasks:-
1. Multiple camera views of
the empty and full yards at the TO’s respective
factory
2. Schematics of the empty and full
yards showing capacity and status of each line in
the holding yards
3. Runs a programme called TO
Tools whereby the TO keeps track of empty
deliveries, full bin pickups, train crewing and
scheduling. See
Traffic Office 1 photo
The TO has a UHF
radio as his main point of contact with the train
crews. A train can move from one mill to another
through a handover process in an area between two
networks known as a Block Zone. This border between
two networks is controlled by one TO and train crews
must change radio frequency accordingly to enter a
“foreign” network and come under the control of a
different network TO. |
| The
Racecourse Mill network console. The networks
projected onto the wall are (from the left)
Racecourse network, in the centre the Pleystowe Mill
network and the network on the right being Marian
Mill network. The monitors on the desk in front of
the Racecourse TO are (from the left) Video monitor
of the Racecourse full and empty yards, TO Tools
computer and then the yard schematic screen. |
Traffic Office 1 |
| This
shot shows the 4th network on the left of shot. The
serene scene is not part of any stress relief
programme! The EMB computers must be shut down and
rebooted once a day. Here the Farleigh Mill network
is being rebooted and will be back online shortly. |
Traffic Office 2 |
|
