A £300m project to reopen the railway line between Airdrie and Bathgate has been given the go-ahead.
The new line could benefit commuters across the country
Preparatory work will start on the Airdrie to Bathgate rail link after the scheme received Royal Assent.
Network Rail now have the legal powers to deliver the link between West Lothian and North Lanarkshire.
The Airdrie-Bathgate Railway and Linked Improvements Bill now becomes an Act of Parliament after receiving unanimous support in the final debate.
Ron McAulay, Network Rail's director for Scotland, said: "Royal Assent provides us with the legal permission to proceed with construction and delivery of this immensely important addition to Scotland's railway network.
"Following the successful passage of the bill through the Scottish Parliament in March, Royal Assent is the milestone we have been working towards over the last two years.
"Network Rail will now seek to move onto site imminently to implement the first phase of the project.
"Commuters in West Lothian will be the first passengers to benefit, with improved reliability on the Edinburgh-Bathgate line as early as next year."
It is anticipated that services will be running the length of the new railway in December 2010.
Network Rail said the environmental benefits include offering a public transport alternative to travelling by car via the M8 and reducing congestion.