After many requests, here is a decent map of the museum ROW with some common questions answered.
Note: The railroad is currently slightly longer than depicted above (in 2007.)
By spring 2015, 2.5 miles of track has been completed to the Top of the Mountain where a run-around track has been added utilizing the grade of the stub siding that the original railroad used to double the hill.
By fall 2016, additional track was laid to the first washout (depicted on the map as such.) This track was ballasted in spring 2017.
In 2017 this washout (and a smaller one north of there) was repaired and at track laid to the landslide (the second washout icon on the map.)
By fall 2018, the bridge at Trout Brook was replaced and the rails now end within sight of Route 218. This track is currently out-of-service, and we hope to open the full "mountain extension" in 2022.
And a map of the Sheepscot Station Campus:
Since the above map was made, the 3-way switch was not constructed, instead a traditional "ladder" track was used to feed the carbarn and woods track. All track shown on that map (with the exception of the 2 roundhouse stalls) is complete. All structures, with the exception of the roundhouse) are now complete.