SCOTRAIL has announced it is to slash capacity on the busy rail routes between Glasgow and Dalmuir, Balloch and Helensburgh on Friday due to faulty and broken down trains.

More than a dozen services on the Helensburgh, Balloch and Dalmuir routes via Glasgow Queen Street and Glasgow Central low level, including several of the busiest evening rush hour trains, will run with three carriages instead of six – affecting thousands of commuters.

READ MORE: Signal fault disrupts rush-hour Helensburgh trains

They are among more than 120 trains across the ScotRail network on Friday which will operate with less capacity than planned due to train faults, broken down trains and a shortage of train crew.

It's the latest day of disruption to ScotRail services and comes after the company apologised to passengers on routes worst affected by delays and cancellations by giving a limited 'free travel' offer - but only on certain routes, not including the Helensburgh line.

READ MORE: Helensburgh commuters miss out on ScotRail 'sorry' compensation offer

According to ScotRail's Journeycheck service the following services on the Helensburgh, Balloch and Dalmuir routes will operate with half the usual capacity on Friday:

10.26am Helensburgh to Edinburgh

11.16am Airdrie to Balloch via Singer

11.19am Cumbernauld to Dalmuir via Glasgow Central and Yoker

12.37pm Balloch to Airdrie via Singer

1.03pm Dalmuir to Motherwell via Yoker and Glasgow Central

2.16pm Airdrie to Balloch via Singer

2.16pm Motherwell to Dalmuir via Glasgow Central and Yoker

3.33pm Dalmuir to Whifflet via Yoker and Glasgow Central

3.37pm Balloch to Airdrie via Singer

4.18pm Edinburgh to Helensburgh

4.58pm Whifflet to Dalmuir via Glasgow Central and Singer

5.16pm Airdrie to Balloch

6.18pm Dalmuir to Larkhall via Singer

6.25pm Helensburgh to Edinburgh

6.38pm Balloch to Airdrie via Singer

8.54pm Edinburgh to Helensburgh

11.32pm Helensburgh to Airdrie