Put your thinking caps on. What would your solution be to solve the problem of the 20 being axed?
OK, so let's look at the route in bits.
Centre - Zetland Rd.
Needed for hospital visits, but with the expansion of Southmead Hospital, over time there is likely to be more demand from the south (e.g. for St Michael's) than the north of the city. So extend a service from South Bristol that terminates in town to Zetland Rd - there used to be a service which terminated there from the Cotham direction a few years ago. Perhaps the 52? 57? Selected journeys on the 50, 51, 90?
Zetland Rd - Kellaway Ave
Covered in parts by the 72 and 505, but the current stops on Clare Ave, Kings Dr and Bishop Rd have no service. Cranbrook Road loses its service to Westbury, but gains one to Whiteladies Rd and Gloucester Rd.
Solution is either to leave Clare/Bishop/Kings unserved, as they were recently when the 20 was re-routed away from them for a while, or as a last resort to reroute the 505 via Coldharbour Rd, Linden Rd, Cranbrook Rd, Clare Ave, Kings Dr, Bishop Rd, Kellaway Ave.
Wellington Hill West
Two options.
EITHER (similar to existing suggestions) reroute the hourly 502 via Wellington hill West, Kellaway Ave, Gloucester Rd, Dorian Rd into the hospital as a 503, but keep the 501 and alternate Sunday 502's unchanged.
OR reroute the 502 at the times as above via Wellington Hill West, Bishopthorpe Rd, Dorian Rd into the hospital as a 503. With this option also rerouting the 505 via Kellaway Ave, Wellington Hill West, Bishopthorpe Rd, Dorian Rd into the hospital.
Both these options give the bottom of WHW a service to Westbury (503) and keep a service along Southmead Rd (18, 501, and hourly Sunday 502). The first option gives the top of WHW a service to Westbury, whilst the second option gives more patronage for the 505 which currently runs non-stop from Tesco Golden Hill to the hospital with just one stop in the opposite direction.
Westbury - Charlton Rd
Currently served only Mon-Sat daytime by the 20.
Extend the 508 so that instead of terminating at Charlton Rd it continues back along Charlton Rd, Pen Park Rd, Monks Park Ave, Southmead Hospital, Southmead Rd, Doncaster Rd, left onto Greystoke Ave and in to Westbury. So it becomes a P-shaped route. Would need intelligent destination blind setting! This gives the bottom of Pen Park Rd a service back, gives some of Southmead and all of Charlton Rd a service directly in to the hospital (not just to the gates), and retains the links to Westbury for Southmead and Charlton Rd.
As part of this change also extend the 505 beyond the Hospital via Pen Park Rd and Greystoke Ave to terminate at Arnside shops. This gives the rest of Southmead a service to the Hospital, and also reduces the pressure on the Hospital bus stop with buses on layover.
There is an extra PVR with the above, mainly on the Wessex 505/508 and the 52 (or similar), but by better timing of the 501/502/(503) to remove some of the massive amount of slack between Parkway and Southmead Hospital, this can be partly offset.