FAQ - TrnBuild

How does TrnBuild calculate fares?

TrnBuild computes fares by accumulating boarding fares and xfer fares into the MODEFARE variable (see MW). If there are farelinks, the fares accumulated by crossing the fare links in the path are added to MODEFARE. There is not a way to separate the farelinks, the various mode fares, etc. It is a difficult process. Ideally, the program should have the same tools for fare as it does for time, distance, etc. But, that process is also questionable: If a path goes through modes 11-13-2-2-13-13-5-2-12, what fares should be assessed for the path? It has used three mode-13 links and three mode-2 links; what fare should be applied?

FARELINK values may be obtained separately; but not by mode. Please see the next question: How can I obtain farelink fares?

How can I obtain farelink fares?

The only way that farelink fares can be obtained is through MW[]=MODEFARE. This command obtains the sum of MODEFARES + FARELINKS.

MW[]=FARE(….) sums the values from FAREMODEFARE.

The program accumulates FARELINK values into modefare, along with the MODEFARE values. To get FARELINK values separately (but not by mode) you need to add / subtract the fares from MODEFAREs from the MODEFARE value:

MW[]=MODEFARE - FARE(0)

Why is the total number of trips reported by the TrnBuild module less than the input trip matrix total?

TrnBuild reports only the trips associated with zones where there is Transit access. If the program determines that it doesn’t need to read the trips for a zone, it doesn’t bother reading them, and then it can’t report the values from those rows. Suppose that you wish to assign only the trips from the downtown area (say zones 1-60). The program is not going to spend the time to read the entire matrix since it doesn’t have to. This speeds up processing in large systems where only selected processing is being done.