Process Path Alteration



  • Path Alteration Process allows the IMs to adapt the originally agreed Active Timetable.
  • The alteration can be proposed by any of the IMs involved in the dossier for the whole validity period of the dossier or just some parts of it.
  • PCS constrain: Cannot request alterations for the days that are in the past
  • The originator IM* has always the right to withdraw the Alteration request and go back to the Active Timetable phase

The whole process consists of the following phases:

  • Path Alteration Conference – IM phase
  • Path Alteration Offer – Applicant phase

How to start the process

First, the IM has to press the"Submit path alteration" button where the process will start with a wizard window. It works in all process types the same way.

Path Alteration types

The following Path alteration types are available in the system:

  • Cancelation of days
  • Modification of departure or arrival time
  • Modification of route
  • Modification of train parameters
  • Border/Handover/Interchange times adaptation
  • Path not available

Affected pairs

Initiator IM has the option to mark manually their partners to be affected. However, if the changes are done only internally without any impact on the partners, the neighboring IM should not be bothered. Of course, PCS is checking the changes that the initiator IM makes and if there are changes that are affecting the border, the system will downgrade the partner's light to yellow automatically.

    Initiator IM is marked with the following symbol: 

    Affected pair marked with the following symbol: 

    Edit timetable

    Once the reason for the path alteration and the involved pair (s) have been determined, the IM timetable will be editable for the initiator IM.

    Changes could be:

    • Times
    • Parameters
    • Calendar

    Accept/Reject changes

    Affected Applicants/IMs should check the changes that were made by the initiator IM the dossier in order to submit it to the next path alteration phase. 

    If for some reason, one of the partners rejects and changes the acceptance indicators to red than must add a mandatory comment to explain the reason for the action.


    When the path alteration process started PCS saves the action automatically into the comment area including the selected path alteration types.

    Also the same happens if an involved parties reject the offer and enter the reason for action:



    The following example will show the alteration process in the Late Path Request process type.

    Start Path alteration

    In our example, the leading IM is VPE, but the Path Alteration is started by the involved IM ÖBB-I.

    The Next step is to select the reason for the Path Alteration indicating it with the type of alteration. In our example, we will modify the timetable, so we choose the modification of the departure/arrival timetable and the modification of the train parameters path modification types. It is possible to select multiple items for path alteration reasons.

    Editing timetable

    The IM can select either to edit the timetable or edit the train parameters, PCS opens the timetable in "edit" mode as in the Path Elaboration phase. 

    The system indicates on the subpath that the process has started, it uses the path alteration word abbreviations( PA) :


    After submitting the Path Alteration request the dossier arrives at the Path Alteration Conference phase and the light of ÖBB-I has been downgraded to yellow, for RCA has been downgraded to blue.

    Change timetable 

    Changes were made, the timetable was shifted 2 minutes earlier in each Austrian station.


    We changed the timetable on the border section that should result in yellow lights on the partners' side:

    Submit Path Alteration offer

    When each affected IM accepted the dossier, the initiator IM can submit the Path Alteration Offer.

    Path Alteration Offer

    When the initiator IM has submitted the path alteration request the dossier arrives into the Path Alteration Offer phase.

    The decision on Path Alteration Offer

    Applicants can check the received offer for IMs Path Alteration request and they can make their decision. The usage of the acceptance indicators (lights) is the same as anytime else. At the end the initiator Applicant has three options:

    • Ask for offer adaptation: in case the offer is not suitable for the Applicants, but only a couple minor modification is missing, Applicants can decide to give it back to the IMs for finetuning the offer. It can be done every time when they receive an offer in Path Alteration. When the Applicant in pairs with the initiator IM clicks this button, the dossier will go back to the Path Alteration Conference phase
    • Accept path modification offer: this is the ideal situation when Applicants accept the offer and the dossier will go back to Active Timetable with the updated timetable
    • Reject path alteration offer: in this case, the dossier will also go back to Active Timetable, but without the changes, so the original timetable (before the Path Alteration process) will remain


    The following example will show the path alteration process in the Ad-hoc Path Request process type. We follow the same use case as above.

    Once the path alteration process has been initiated by the initiating IM, the IM's timetable becomes editable and can request changes for the FUTURE DAYS by adding a NEW SUBPATH.

    The timetable is not editable when the dossier enters the path alteration process because it contains days from the past, so a new subpath needs to create!


    Looks the same when the dossier entered the path alteration process for the first time.

    Change timetable

    Changes were made, the timetable was shifted 2 minutes earlier in each Austrian station.


    We changed the timetable on the border section that should result in yellow lights on the partners' side:

    The next step is to define the running days in the calendar, the new subpath added with an empty calendar. The system indicates a warning message on the control.

    In the calendar, the past days and the future days are displayed differently.  

    If the path alteration process started in the past for e.g. spending too much time with the preparation of the offer then you need to adjust the validity period which will update it to today's date and restores back the passed days to the original path.

    In our example, the path alteration process started one day earlier, the initiator IM decided to continue working and preparing the request on the next day (2020-09-05 which is today's date).

    In the calendar, the 2020-09-04 has a faded green color to show that this day will not be part of the new request.


    The system indicates it with warning messages. In order to continue to submit the path alteration, needs to adjust the validity period for today's day.

    Please note that there will be no change for 2020-09-04, even though it was originally requested! The Adjust the validity period copies today's date as the start date, click Save.

    After if the affected IM also accepted the request the initiator IM can submit the path alteration offer.

    The process continues the same way as in the case of the validity period in the future. 

    Please read the path alteration phase documents for further information.