Roads across Chorley could be closed for up to 20 weeks to allow the electrification of the railway line.
The proposals include changes at 10 bridges in the town and involve track lowering, which will also see trains diverted.
The extensive work will also see the reinstatement of Chorley’s historic Flying Arches, which were removed in 2008 for restoration as part of £7m improvements. The works have been scheduled by Network Rail for 2014 and will take a year to complete.
The bridges affected by the works include:
n Brooke Street
n Alker Lane
n Chorley tunnel
n River Chor Aqueduct
n Harpers Lane
n Stump Lane
n Lyons Lane
n Chorley Road
n Rawlinson Lane
n Railway Road, Adlington
In most cases they will have to be rebuilt so they are high enough to fit the train and overhead wires through as well as the pantograph, which attaches the train to the cables.
The work will tie in with the re-instalment of the Grade II listed Flying Arches which were removed to allow for the lowering of the track formation, improvements to drainage and to allow modern trains to pass through at full speed.
It took around 40 workers hundreds of man hours to dismantle the 16 stone arches and commuters used rail replacement buses throughout the work.
They have since been stored in compounds on Bengal Street.
Formal planning applications are expected to be submitted next month.
Chorley MP Lindsay Hoyle, a supporter of the electrification, said: “The electrification will allow for extra capacity on the crowded trains and will mean new investment in carriages.
“The problems caused by the works in the short-term will be negated in the long-term by the benefits of the improvements.”
Network Rail is in talks with Lancashire County Council over the road closures and has briefed councillors in Chorley.
A spokesman said: “Where possible, we try to avoid reconstructing structures as this is usually the most disruptive and costly option. However, due to the nature of the work, this is often unavoidable.”