Motorists face delays on one of the main routes into St Helier for the next three months.
Drainage work starts today (5 February) on the Inner Road (La Route de St Aubin) between West Park and Bay View Court.
Delays are expected around West Park for the next 12 weeks.
Sections of the westbound carriageway will be closed and temporary traffic lights will be in use.
The government project will increase the capacity of the sewage network when new houses are eventually linked to it.
Surface water from rainwater run off will be separated from the foul drainage network to ease pressure on the First Tower Pumping Station, the liquid waste network and Bellozanne Treatment Works.
A report published last May highlighted how Jersey's ageing sewage system is struggling to cope with a population double the size it was designed for, and is one of the biggest barriers to the delivery of new homes to ease the housing crisis.
The work on the Inner Road is expected to take until 1 May to complete.
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