Construction of the tram line will take place over about 2½ years - between October 23 and April 2018 - but the line is not expected to be in service until late in 2018.

Transport Minister Andrew Constance and Roads Minister Duncan Gay revealed on Thursday they had reneged on an agreement not to remove an existing cycleway on College Street before replacing it with a separated path along Castlereagh Street.

Other cycleways promised by the Coalition government in 2013 - separated paths along Pitt Street and King Street in the city - will not be built until 2019.

Asked about the safety implications of removing a separated cycleway during a period of major road construction - when more people may want to cycle to avoid road congestion - Mr Constance said: "Everybody is going to be affected by this build".

"It wouldn't matter if they are a cyclist, or a bus commuter or a pedestrian, or someone who drives a delivery vehicle. This is going to result in changes," he said.

Ray Rice, the chief executive of Bicycle NSW, said the policy announced on Thursday would put lives at risk by forcing bike riders on to congested roads.

"The decision is bad for transport, bad for health and bad for business," said Mr Rice.

"Businesses have been significantly investing in end-of-trip facilities for bicycle riders, however the government is not going to provide the on-road facilities essential to safe commuter cycling," he said. "It is the government that is unprepared and the ministers who have failed to plan ahead."

The Mayor, Cr Moore, offered similar sentiments and, on a day a cyclist died in a collision with a truck in the eastern suburbs, accused the government of endangering public safety.

"Bike trips have more than doubled over the last four years in our local area, and where there are cycleways, they've doubled again," Cr Moore said.

Mr Gay said the lane used by the College Street cycleway would be used for buses during construction of the light rail line. The minister has also backtracked on his previous policy of implementing a peak-hour only cycleway on Castlereagh Street.

A new position, the co-ordinator general CBD Transport, will be filled by Centre for Road Safety head Marg Prendergast, who will be responsible for managing traffic in the city.

Mr Constance said the most disruptive stages of construction would be from August to September 2016 and May 2017 when 17 construction stages would be under way in the city.

A new bus timetable will be in place on October 4, though Mr Constance would not detail how bus routes would be rearranged.