The Bristol Metrobus route will run 2.5 miles from Ashton Vale to the Temple Meads train line with works broken up into seven separate design and build contracts.
Several contractors have returned tenders for a host of work packages with the aim of starting work early next year.
The main £30m design and build element involves construction of a two-way segregated busway between Long Ashton Park and Ride and the Museum of Bristol.
The next biggest package at £13m involves building a new overbridge at Stoke Lane onto the M32.
A further five contracts will involve two new bridges and three upgrade and strengthening jobs to listed bridges on the city centre route worth together around £10m.
Government funding is being sought for the two other routes, which also have planning, in the overall £200m regional scheme.
A total of £51m of funding is being sought for the northern route (Cribbs Causeway) in South Gloucestershire, with local councils contributing the same amount.
A total of £28m of transport funding is being sought for the southern route (Hengrove), with councils set to invest £17m.
The £200m project has been devised by the West of England Partnership – an alliance between the four councils in Bristol, Bath, South Gloucestershire and North Somerset.
