Mzzzs
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Basically is there a calculation to calculate how many trains required to run an hourly or half-hourly service?
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How to calculate the number of trains required to run a service?
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edwin_m
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Take the one way journey time, add the minimum time it needs to spend at the terminus. Then double the answer to get the time from departing A to travel to B and back and be ready to depart from A again. Then divide the new answer by the interval between successive services. Rounding up to the next integer gives the number of trains needed in service.
So for example, journey time 40min, time at terminus 10min, total 50m, double to 100min. If you want a train every 30min then the answer is 3.3333 which rounds up to 4 trains in service.
A rule of thumb is to have 10% for trains not in service then round up again, which would give 5 trains for a microfleet to run this one service. It would normally be done for a larger fleet running several services.
So for example, journey time 40min, time at terminus 10min, total 50m, double to 100min. If you want a train every 30min then the answer is 3.3333 which rounds up to 4 trains in service.
A rule of thumb is to have 10% for trains not in service then round up again, which would give 5 trains for a microfleet to run this one service. It would normally be done for a larger fleet running several services.
Surreytraveller
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And you can combine different routes, so a train arriving in one one route then forma a train going back out on a different route. This can reduce the number of units required, but doesn't help when disruption occurs, as it causes disruption to spread to other routes (as does having crews interwork between different routes - this can be compounded when crews interwork between different routes to the stock)
Djminisite06
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Journey time outbound + Journey Time inbound + outbound turnaround (timetable planning rules) + inbound turnaround (timetable planning rules) let’s you work out a full round trip time.
Now if the turn around at the origin can be accommodated before the next scheduled departure that set can be used again. Otherwise it’ll have to sit and wait and you’ll have to add a new set. Repeat until this process until you meet the first set back at the origin (and ready to go) and you’ve got your set requirement.
It’s also good to consider fleet availability. If you need 10 sets for a service and your fleet availability is 90% (arbitrary number for the sake of this example) then divide the sets required in the timetable by 0.9 to get 11.1 (this covers sets needing maintenance etc) then since we don’t have .1 of a train then we need to round up to 12 sets.
This hasn’t considered traincrew though.
Now if the turn around at the origin can be accommodated before the next scheduled departure that set can be used again. Otherwise it’ll have to sit and wait and you’ll have to add a new set. Repeat until this process until you meet the first set back at the origin (and ready to go) and you’ve got your set requirement.
It’s also good to consider fleet availability. If you need 10 sets for a service and your fleet availability is 90% (arbitrary number for the sake of this example) then divide the sets required in the timetable by 0.9 to get 11.1 (this covers sets needing maintenance etc) then since we don’t have .1 of a train then we need to round up to 12 sets.
This hasn’t considered traincrew though.
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