He said: “I appreciate the works will take a long time, but I’d ask residents to bear with us. The outcome should be worth it.
“Mortimers Lane is too fast. Average speeds are around 36mph (58 km/h) in a 30mph limit.
“Cyclists, and to some extent pedestrians, are deterred from using Mortimers Lane because it is not safe.”
During the project, traffic will only be allowed to travel eastbound, from Eastleigh towards Upham, said the Local Democracy Reporting Service.
The work will involve widening the footpath to accommodate the pedestrian and cycle route.
There will also be new bus stops, a traffic-calming pinch point and a new pedestrian crossing.
The first two weeks will be spent diverting a sewer between Mimosa Drive and Knowle Lane, with the remaining work starting in early February.
Knowle Lane, which leads to a household waste and recycling centre, will remain open as normal.
Temporary traffic lights will be used at its junction with Mortimers Lane and signs will be put up in Upham to discourage drivers from using the route as a shortcut.