System and method for controlling braking of a train

A train-home component of a positive train control system comprising an on-hoard computer for a train, the on-board computer being programmed to select a most restrictive target from among a plurality of targets when the train is located at a current position by:

• (a) initially including all of the plurality of targets in a group of targets to be evaluated;
• and
• (b) performing a series of evaluations on selected pairs of the targets in the group until only one of the targets remains in the group, wherein in each of the evaluations a first one of the targets remaining in the group and a second one of the targets remaining in the group are evaluated together to determine which one of them is a more restrictive target based on a profile velocity to the first one of the targets and the target speed associated with the second one of the targets, wherein in each of the evaluations the first one of the targets is the target remaining in the group that is furthest from the current position of the train and the second one of the targets is the target remaining in the group that is second furthest from the current position of the train, and wherein following each of the evaluations the one of the first one of the targets and the second one of the targets not determined to be more restrictive is removed from the group, and wherein when all of the evaluations are completed the one of the targets that remains in the group is identified as the most restrictive target.

A method of selecting a most restrictive target from among a plurality of targets for a train having an on-board computer, each of the targets having an associated target speed, the train being located at a current position, the method comprising performing the following steps in the on-board computer:

• (a) including all of the plurality targets in a group of targets to be evaluated;
• (b) indentifying as a first target the one of the targets that is located furthest from the current position and as a second target the one of the targets that is located second furthest from the current position, and eliminating the first target and the second target from the group;
• (c) determining a profile velocity to the first target;
• and
• (d) (1) if the profile velocity to the first target is greater than the target speed associated with the second target or if a time to penalty brake application for the second target is less than a predetermined amount:
• (i) determining whether any targets remain in the group, and (ii) if no targets remain in the group, setting the most restrictive target to be the second target and ending the method, and (iii) if targets do remain in the group, identifying as the first target the second target, identifying as the second target the target remaining in the group that is furthest from the current position, removing from the group the target remaining in the group that is furthest from the current position, determining the profile velocity to the first target, and repeating step (d) one or more times until the method ends;
• (2) if the profile velocity to the first target is not greater than the target speed associated with the first target and if the time to penalty brake application for the second target is not less than the predetermined amount:
• (i) determining whether any targets remain in the group, and (ii) if no targets remain in the group, setting the most restrictive target to be the first target and ending the method, and (iii) if targets do remain in the group, identifying as the second target the target remaining in the group that is furthest from the current position, removing from the group the target remaining in the group that is furthest from the current position, and repeating step (d) one or more times until the method ends.

A train-borne component of a positive train control system comprising an on-board computer for a train, the onboard computer being programmed to select a most restrictive target from among a plurality of targets when the train is located at a current position by performing a method including the following steps:

• (a) including all of the plurality targets in a group of targets to be evaluated;
• (b) indentifying as a first target the one of the targets that is located furthest from the current position and as a second target the one of the targets that is located second furthest from the current position, and eliminating the first target and the second target from the group;
• (c) determining a profile velocity to the first target;
• and
• (d) (1) if the profile velocity to the first target is greater than the target speed associated with the second target or if a time to penalty brake application for the second target is less than a predetermined amount:
• (i) determining whether any targets remain in the group, and (ii) if no targets remain in the group, setting the most restrictive target to be the second target and ending the method, and (iii) if targets do remain in the group, identifying as the first target the second target, identifying as the second target the target remaining in the group that is furthest from the current position, removing from the group the target remaining in the group that is furthest from the current position, determining the profile velocity to the first target, and repeating step (d) one or more times until the method ends;
• (2) if the profile velocity to the first target is not greater than the target speed associated with the first target and if the time to penalty brake application for the second target is not less than the predetermined amount:
• (i) determining whether any targets remain in the group, and (ii) if no targets remain in the group, setting the most restrictive target to be the first target and ending the method, and (iii) if targets do remain in the group, identifying as the second target the target remaining in the group that is furthest from the current position, removing from the group the target remaining in the group that is furthest from the current position, and repeating step (d) one or more times until the method ends.