The B9150 follows the pre-bypass route of the A9 south of Newtonmore.
The road starts on the A9 at Raliabeag, where a short link has been built between the new and old roads, the latter continuing to the south past the picnic site and becoming an unclassified off-slip from the A9. The B9150 then slowly diverges from the new road, as they head north, before sweeping left to cross the railway. A side road to the right just before the bridge is the former line of the B970, cut off and overbuilt when the A9 bypass was constructed. The bridge itself is now controlled by traffic lights, partly due to the sharp turns on the approaches.
The road then returns to the original straight route, with aerial photography suggesting that the pre-railway alignment is still traceable amongst the trees. As the road drops down the hill, it crosses the dramatic Spey Bridge, a 3-arch concrete structure designed by Owen Williams in the 1920s. After a brief run across the riverside meadows, the road comes to an end. One of the most interesting things on this road's 1.3 mile length is this junction at the northern end. It appears that it has never been changed since the A9 bypassed Newtonmore and Kingussie, leaving the A86 to TOTSO with the upstart B9150!