Calderdale Council said that work is taking place following continued significant movement of the road over the last 12 months.
A spokesperson said: "This extended lane closure is taking place now as the reopening of Park Road has allowed us to minimise what would have otherwise been severe access issues for residents and businesses.
"The work will take around 10 weeks to complete and the lights will be manned to minimise disruption as much as possible.
"We apologise for any inconvenience that may be caused as this essential work takes place."
The key route between Brighouse and Elland was only fully reopened on Friday after two years.
A key road between Elland and Brighouse will reopen early this month, following major repair work.
Park Road was closed in February 2020 when it was seriously damaged by a landslip after significant flooding caused by Storm Ciara.
Vertical movement of 300mm caused cracking over a 60-metre length of the road, as well as some smaller tension cracks, which meant that it had to be fully closed to all traffic for safety reasons.
The Council worked with Esh Construction to carry out significant work to stabilise the road.
This has involved the installation of 157 deep bored piles and ground anchors, tied together with a concrete capping beam. Further work has also taken place to improve drainage to help deal with future heavy rain.
The complicated, specialist and costly nature of the repairs meant that additional funding had to be identified.
The full repair plan was agreed after the Council successfully bid for £1.8 million from the Government’s Getting Building Fund, following approval from the West Yorkshire Combined Authority in May 2021.
The Combined Authority secured £52.6 million from the Government’s Getting Building Fund to accelerate 15 “shovel-ready” projects in response to the pandemic, helping create nearly 2,300 new jobs and safeguard a further 500.
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