The older I get and the weaker my knees become, the more I appreciate these little vehicles which transport people around so many cities and towns in Europe. By using the bus/train to whizz around the place first, you can then decide what is worth going back to see properly and what is not.
Saarburg is no exception, the little red train does the circuit about every 15 minutes and can be picked up anywhere along the way. You can't miss it. Everywhere you go, you will see it.
The trains run from Trier to Saarburg twice an hour all day long. I can't rightly remember the fare but it was only a few euros for a round trip ticket. The journey takes about 20 minutes.
When you get off at Saarburg, go straight down the main road leading to the bridge over the river. Cross the bridge and proceed down the ramp on your right towards the boats. Then do an about face, proceed under the bridge and follow the road to the town centre.