The quick answer is that there is. I haven't done this for a while but one of the trigger rules will let you throw a switch to a set position. However, you need to be aware that there is always a danger that the particular switch may have already been "grabbed" and locked by another moving consist in your session and disaster or confusion can be the result.
You can always do it in two steps with rules. Same danger does apply that Pware already mentioned: If it is already locked, it wont change.
Step 1: Put a trigger at the right distance (speed and situation dependant) of the switch.
Step 2: Add the "Trigger check" rule and the "Set Junctions" rule to the session.
