The single track railway line outside Montrose will be replaced with a dual line as part of a £200m investment to improve rail journey times.
The one-and-a-half mile section of single track between Usan and the South Esk viaduct at Montrose Basin means that at certain times trains have to slow down and wait for others to pass.
The move will help the Scottish Government meet a pledge to reduce rail travel times from Aberdeen to the Central Belt by 20 minutes.
A Government spokesman said: “The £200m will focus on opportunities to increase line speeds and remove major capacity constraints along the key sections of the route with a particular focus between Aberdeen and Dundee.
“This will include options for double tracking of Usan Junction and South Esk Viaduct at Montrose.
“Exploiting all engineering opportunities along the route may well cost in excess of £200m.
“However, delivery can be phased and this £200m is a substantial contribution that will allow us to focus on the biggest challenges and take forward the work quicker, with benefits delivered earlier to Aberdeen and the surrounding area.”
The work will be delivered in the next five to 10 years.
Montrose councillor David May said it was “very good” news.
He said: “It’s currently a major problem because it’s a single track as you come into Montrose from the south. At the moment trains slow down and wait for others to pass.
“It will be a major piece of construction work to make it dual track. It should certainly help speed things up in the long run.”
Money will also be spent making a range of improvements to Aberdeen Station.
However, opposition parties claimed the announcement of cash for improvements to the Dundee to Aberdeen rail line and the Laurencekirk road junction was not new money.
Scottish Conservative leader Ruth Davidson said she did not get satisfactory answers from the First Minister over whether this is “simply a rehash of a previous pledge”.
The First Minister’s spokesman said the projects have previously been listed by the Government, but were not approved.
He said: “You’ll have an infrastructure plan going forward which may have costs attached to it but there is no money released for it. This is new money.”