Phase two of the Belfast on the Move scheme is aimed at improving the city centre road network, but there is a risk of traffic disruption in the meantime.
The work is expected to be carried out at "off peak" times to avoid undue delays and resurfacing of roads will be carried out at weekends and overnight where possible.
The project will involve changes to lanes in Great Victoria Street, Fisherwick Place, Grosvenor Road, College Avenue, College Square East, Wellington Place, Donegall Square North, Donegall Square East and Chichester Street.
Cycle tracks will be introduced in Victoria Street and Ann Street, and there will be resurfacing work in College Square North, Durham Street and Grosvenor Road.
We are encouraging the use of public transport for those who can readily access it and, at the same time, creating more road space for those who are simply unable to use public transport.
Roads Minister Danny Kennedy
Many drivers complained of congestion in the city when the first set of bus lanes opened last September.
The Department of Regional Development said traffic flows have since reduced, while bus usage has increased by around 1,500 passengers per day compared to 2011.
Earlier this month, Roads Minister Danny Kennedy advised: "It is expected that, like phase one, there will be a 'bedding in' period for the new works.
"We would therefore ask everyone to be patient and allow extra time for their journey.
"The aim of Belfast on the Move is to make the city centre more accessible to everyone."
Motorists in the city centre are advised to familiarise themselves with new traffic management arrangements.
New bus priority measures - including bus lanes at the back of City Hall - are operational on May Street, Donegall Square South and Howard Street.
The bus lanes, which accommodate public transport, cyclists, motorcycles and permitted taxis, will be operational from 7am to 7pm from Monday to Saturday.
Roads Service urges drivers who do not need to travel via the city centre to use alternative routes such as the M3, Westlink and the Outer Ring Road (A55).
Hope Street has also opened to two-way traffic, providing an additional northbound route - via Hope Street, Sandy Row, Durham Street and College Square North - for traffic on Great Victoria Street and to also improve local access in the area.
- Great Victoria Street (Hope Street to Grosvenor Road) and Fisherwick Place - lane reallocation and introduction of a north-bound bus lane
- Grosvenor Road (Durham Street to Great Victoria Street) - lane reallocation
- College Avenue and College Square East - lane reallocation and introduction of a south-bound bus lane
- Victoria Street - introduction of a cycle track from Chichester Street to Gloucester Street
- Ann Street - introduction of a 2 way cycle track from Victoria Street to Oxford Street
- College Square North, Durham Street and Grosvenor Road - resurfacing
- Wellington Place, Donegall Square North, Donegall Square East and Chichester Street - lane reallocation and introduction of bus lanes