How are you moving from Surveyor to Driver?
The method that works in TRS19 Standard and TANE, and still works in TRS19 Platinum and Trainz Plus (both of which have the new UDS interface), is to save your edits, exit Surveyor back to the Surveyor/Driver menu, select the
Session (or select the
Route then click
View Sessions and then select the
Session) and click
Drive Session. As I mentioned, this should work exactly the same as it does in TRS19 Standard and did in TANE, TRS12, 10, 09.
TRS19 Platinum and Trainz Plus have an alternative method. In Surveyor, after loading both the Route and the Session, open the
Edit Menu and select
Driver Mode. Driver will start with the Session paused (the word "Paused" will be large on the screen). This will start the Session in its
current state (an important concept). By "unpausing" you can run the Session for as long as you like and then, using the same method, switch back to
Surveyor Mode. You can then edit the Route and/or Session and then resume running the Session in
Driver Mode. Each time you run the Session this way, you will change its
current state - consists will have moved and some or all Session Rules would have changed their status (e.g. some would have been completed, others would have started). If you edit the Session by, for example, adding new consists, new driver commands, new drivers, adding/editing Session Rules - anything that alters the position of consists or the state of the Session Rules - then you will be changing the operating conditions of the Session. You then need to restart the Session Rules.
For example: When a Session starts in
Driver Mode the
Driver Setup Rule, with its drivers and their assigned commands, is immediately executed. If you drop back into
Surveyor Mode, edit the drivers and/or their commands and then jump back into
Driver Mode the
Driver Setup Rule is not restarted so the new commands and/or drivers you have added
will be ignored. In the Session Editor after making the jump back into
Surveyor Mode the rules that have been completed will be marked as "(complete was-complete)". You need to restart these rules or, alternatively,
Restart All Rules (button at the bottom).
See the Trainz Wiki page
https://online.ts2009.com/mediaWiki/index.php/How_to_Use_the_UDS_Interface for all the details of using the UDS.
As John has pointed out, the UDS is a Route and Session development tool but, provided you take some sensible steps, you can use it to run long Sessions from start to finish, with many pauses and edits along the way, without any problems.
My suggestions.