With the demise of the cable cars in 1947 and the ripping up of the rails, diesel buses were put into service as replacements.
At that stage of course the Stuart Street extension as we know it today did not exist.
During all the earthworks the buses had to detour from where Moana Pool is now, around Littlebourne Road, into Tweed Street, then up to Highgate via Fifield Street. With the construction of the Highgate bridge the route from Highgate to Taieri Road was via Wright Street, then Tyne Street. See map below.