Train crashes in real life are serious. they can be fatal, in model form they can damage locos and rollingstock.
Safeworking is a system to prevent trains crashing. There are many ways to do it in real life and in model form.
This become very important for a large DCC based layout. some will say it is an advantage to some, and a real pain to others. DCC locos are independantly controlled and can crash into each other if you let them. Like real railways a DCC layout has to contend with cornfield meets, and running up the rear of another train.
The Problem:
On the Costerfield line, we found problems. How the layout operates is with station based operators who manage the station, do all shunting. Next there are a few operators who run the train between stations and the staging yards.
One was Greytown, which has the mainline come around a 180 degree curve sround a wall. The other side of the station heads into a gap in the wall, on the way to the lower staging.
What was happening was trains entered the station while the station operator was shunting. Particularly the mainline right into the wall, train sudden rushed into the station, and -bang- -crash- sometimes it could be a point in the wrong place, or sometimes a train in the way.
The top right photo shows Greytown from where the operator stands. I have a red line pointing to where it enters the station. No time for a train to stop nicely if they find the line wrong !
It seems attention focused on the section between stations as a focus, yet the trains entering the staons is ignored. At the moment the station operator has no way/means to stop a train comming into his yard/station limits.
So we have two things. One is safeworking between stations, the other is entering stations.
The entering staion part is not too hard, we simply need a home signal at each end of a station. If placed at RED the train driver cannot pass.
While this may be a model signal on the latyout, and there shold be a post identified as the home signal, due to the way the layout operates
we might need a repeater signal indicator so the operator at the other end of the room can see if they can or cannot come into the staion. This
is especially so at the Greytown as the train come in the opposite direction to the operator's position. Costerfield has a similar viewing problem as well.
The operator simply needs two switches, one for the up end, one for the down end, and each just is a on/off or proceed or stop.
The edited photo on the left shows the repeater lights, one for Greytown, one for Costerfield.
This is the situation in Costerfield. Again trains enter one end the opposite way the operaotr can see, ie they watch the train comming to them around a backdrop. Like Greytown they may not be watching from the end of the staion, and thus enter the area unknown. Like Greytown a repeater signal will be handy to see if the home signal is stop or proceed.
The end nearest the aileway where the operators tend to stay, a modelled home signal will be quite OK. Even though a semophore would be ideal as it physically shows the aspect, Ok at the front, but for the rear, they may be hard to see, so the repeaters would still be needed.
I think this is the major flaw at the moment. Trains are always seemingly entering stations before the station operator is ready. At the moment there is more a verbal authority to enter - and it does not work all the time !
The diagram above shows the mainline. Obmitted are the staging yards at each end, and the branch to Ninamanina. Each station has a home signal, which is also the yard limit where trains can shunt to. So between the home signals is the safeworking block Withon the home signals is the domain of the station operator. Haven't shown any starting signals, wihich are optional, as often a mainline driver will ask if it is ok to depart.
Another part of the station's operations is the station operator may not really know there is a train on the way, or wanting to enter the station limits. One could use a track occupany detector, or perhaps a infrared detector to energise a small LED and perhaps even a mutes buzzer. Full size have a buzzer that goes off when a train first enters a section, this would alert the station that there is a train waiting to come in, and could alert him that a train is on it's way, but how long before the train gets there- so a arrival at home stick would be better.
Next up is between station working.
The lessor problem has been the track sections between stations, as usually operaotr are looking and can see the mainline. Mark has already inmplemented a form of safeworking in a to/from switch to allow you to set the direction of a section, and get a green to depart if the staion you are going to pulles for accept, and the station you leave sends the train But it does require the station operators to pull the right way as required. It works well, but others wish to expand. and with Hazeldale loop unmanned, the mainline operators have to do that themselves.
There many ways to do safeworking. The diagram above has cut out Hazeldale loop just as a example of two stations.
- CTC - Centralised Traffic Control. You need a dedicated person to operate a control panel that can work signals at every loop,station and staging yard. He would need to be seperate and need a radio system to communicatr with drivers and himself. Complicated, lots of worong to do, even if done simply.
- Train Orders - again you need a dedicated person to sit somewhere and issue orders via the radio to mainlione operators. This Train Dispatcher usually has the timetable and then plots the actual movement on a graph. Again it can involve a lot of paperwoprk as one often has to fill out the train order, and reread it back to verify,
- Staff and ticket. - this is quite simple, you make a staff for each section and he who has it can drive into
the section. Lots of rules needed to follow, as
one can allow a 2nd train to follow the first etc. Not good if you have more than 2 trains heading in the same direction, usually works well when you have opposing moves all the time.
This can be simply or very complicated. One could make a electronic Staff Machine, and when the "staff is removed, it sets all signals to STOP, thus the only train to enter the section is the one with the staff. When the train gets into the next destination, the staff is put into the staff machine there, opening the section. A ticket allow the first train to enter the section, get to the next station. Thne the next train departs in the same direction with the actual staff. It gets complicated, as one can have a multi bit staff, ie the first train gets one half, the second the other half, assemble the staff to then put into the machine. One could use bells simply to communicate the trains. - Double line block - used on double track mainlines, but there is a single line block, rare but has been done. Not so sure on this but again a way for station staff to signal each other to let a train enter or leave. It relies on the station operator each end to set up the route, then give the green signal to the driver to go. This will need a instrument built to do the job. It is the system that uses bell signals the most. Mark's existing system is a form of this, setting the direction, and if both ends agree, the signal goes green !
We have to remember we have one or two station operators, they have to be signalmen, shunter, driver, and yardman all at once. Too muh to do - will result in mistakes. We have to get a easy system.
When trains ran from one signalboz to the next, on a mainline, they had track circuits. So they could see if there was a train between signalboxes. CTC and double line block would need track sections ideally. If obn a staff their home signals were there to protect the train.
Craig Mackie's Casino Layout also uses sections between staions on a single track. He also runs NCE DCC
His solution was a simply slideswitch and LED. The rule is if the section is RED you cannot enter. If it is green you can, but you have to slide the switch turnong the section to RED,
then at the end you slide the switch at that station and the section goes to green. Much like the idea of 240v wiring for
two switches controlling one set of lights.
The photo on the right shows the station called "The Risk". the sectio to the lefdt is unoccupied, but the right one is, so ther must be a train on it's way. the phot also shows his headphone jack for CTC communication. One plugs in and press to talk........