gregcthe dispatcher would throw the switches at either end when he sees that the adjacent blocks are no long occupied? or could this happen automatically (is this an example of "fleeting")?
Depends on the level of automation in the dispatching system.
If it is an older system then yes, when he sees the CP cleared he can line the switch and route the other way.
In more advanced systems, the dispatcher can "stack" movements at a CP, a series of sequential switch postion and route clearings. Fleeting is generally a system that generally keeps reclearing a single route in a single direction.
In a very modern system, the planning engine might make the meet and clear the trains away from it untouched by human hand. Or it might randomly line a train into a siding for no apparent reason ("phantom meet"). Technology is a wonderful thing.
Dave H. Painted side goes up. My website : wnbranch.com
jeffhergertDepending on conditions mentioned and timing, neither train may have to stop.
the dispatcher would throw the switches at either end when he sees that the adjacent blocks are no long occupied? or could this happen automatically (is this an example of "fleeting")?
greg - Philadelphia & Reading / Reading
dehusman Bonded= having rail bonds, wires connecting rail to rail to allow detection. Bonded means there is a detection circuit and unbonded means there isn't a detection circuit. Lunar=A blueish white signal, indicates a restricting indication, proceed at restricted speed. If a railroad doesn't use lunar then it will have a restricting indication. Same thing. Rolling meet= One train is pulling into the siding the same time the other train is pulling past the switch at the other end. If the siding is long enough, and the train on the main is short enough, the train on the main might not even stop.
Bonded= having rail bonds, wires connecting rail to rail to allow detection. Bonded means there is a detection circuit and unbonded means there isn't a detection circuit.
Lunar=A blueish white signal, indicates a restricting indication, proceed at restricted speed. If a railroad doesn't use lunar then it will have a restricting indication. Same thing.
Rolling meet= One train is pulling into the siding the same time the other train is pulling past the switch at the other end. If the siding is long enough, and the train on the main is short enough, the train on the main might not even stop.
Depending on conditions mentioned and timing, neither train may have to stop.
Jeff
dehusmanBonded sidings can get better than a lunar into them.
dehusmanSo no rolling meets?
??
gregci had assumed that a siding and the mainline track parallel to it both have block detection.
Maybe. "Bonded" sidings will have detection. "Unbonded sidings" will not.
Bonded sidings can get better than a lunar into them. Unbonded sidings the best you can get is a lunar.
on the club layout, extra switches were added to the tortoise machines switching the siding so that only the mainline or siding is powered.
So no rolling meets?
a single detector (PSX) reports block occupancy for the pair. because only one track is powered, the occupancy detector only reports if the powered track/block is occupied and will report the block(s) cleared if the switches are thrown to an unoccupied track even though the other track is occupied.
Well that is certainly the economical way to do it, but not at all how the prototype works. The main track almost always has detection.
The older the signal system is, the earlier it was installed, the more likely to have unbonded sidings. Systems installed prior to the 1970's had a lot of unbonded sidings from what I remember seeing. The more modern a system is the more likely to have bonded sidings.
There is even one step lower on the wooden axle scale, CTC with unbonded sidings and a spring switch at one end. We had that on the old MP Pine Bluff Sub. Probably the same signal engineers your club used. 8-)
Prototypes have indecent switch indication and both main and passing siding have occupancy detection.
I would think the club dispatcher would have a tougher time keeping track of where every train is and occupied sidings for planning passing moves with that system They have. But it is thier train set and rule #1 applies
A pessimist sees a dark tunnel
An optimist sees the light at the end of the tunnel
A realist sees a frieght train
An engineer sees three idiots standing on the tracks stairing blankly in space
i had assumed that a siding and the mainline track parallel to it both have block detection. is this true or perhaps only the mainline track has detection?
on the club layout, extra switches were added to the tortoise machines switching the siding so that only the mainline or siding is powered. a single detector (PSX) reports block occupancy for the pair.
because only one track is powered, the occupancy detector only reports if the powered track/block is occupied and will report the block(s) cleared if the switches are thrown to an unoccupied track even though the other track is occupied.