Page 98 - 捷運技術 第35期

90 Jeffrey S. Stover CITYFLO 650 System Overview

A Conflict Point is defined as the end of movement authority, i.e. the location along the track
beyond which is a train is not permitted.
The Region ATP uses these Conflict Points to properly and safely manage the movement of
trains throughout the railway network. Typical Conflict Points include Rear of Train in Front, End
of Line, A point not set or End of route for a particular train.

3.4 Train Occupancy in CITYFLO 650
In moving-block systems, train occupancy is generated by the train and sent back to the
wayside control system. This train generated occupancy is based upon the worst-case braking of the
train.

The trainborne ATC is responsible for calculating the location and occupancy of the train.
The trainborne ATC generates the train’s occupancy using the worst-case stopping distance and
transmits this “virtual occupancy” to the wayside ATC. The trainborne ATC is programmed with the
worst-case performance parameters of the propulsion and braking systems and uses these
parameters to calculate the worst-case braking distances.

During each task cycle, the emergency braking distance is calculated for a final speed of zero
and also for final speeds of the lesser of each segment’s civil or restricted speed limit in the train’s
route. These emergency braking distances are compared to three different distances:

1. The distance from the train’s head footprint to the front conflict point

2. The distance from the train’s head footprint to the service braking distance（the service brake
conflict point）

3. For each segment in the train’s route, the distance required to slow the train to that route
segment’s line speed limit if it is lower than the current segment’s line speed limit
If any of these three distances are less than the associated emergency braking distance or if one
of the safety restrictions requiring emergency braking is violated, then the emergency brakes are
applied.

Otherwise, if all three of the above distances are greater than the associated emergency braking
distance, then the service braking distance is used. The service brakes are not applied, unless one of
the safety restrictions requiring service braking is violated or until the train enters its service
braking distance（i.e., its service brake stopping profile）.

The service braking distance is the braking distance that is applied when coming to a normal
stop utilizing the service braking rate. The service braking calculation is based on ride comfort and
is therefore a jerk-limited, acceleration-bounded braking scheme. The service braking distance is
calculated for the purpose of determining the distance required to allow the trainborne ATO to stop
the train at a comfortable rate to prevent the trainborne ATP from having to initiate an emergency
brake stop.