The new X35 service replaces the full length of route 4B between Falkirk and Croy via Banknock, Banton and Kilsyth.
Buses then extend from Croy to Glasgow via Craiglinn (Main Road), Mollinsburn, Moodiesburn Cross, Muirhead, Crowwood and the M80/M8.
Services run every hour during the day and in the early evenings on Mondays to Saturdays, maintaining the existing frequency currently offered on route 4B.
The two early morning links between Croy and Cumbernauld Town Centre that service 4B provides on Saturdays will also be maintained by service X35.
The route of the X36 service from Stirling to Glasgow via Cumbernauld Village will be revised to operate via North Carbrain Road, as a result, the stops at Cumbernauld Town Centre will no longer be served.
Further alterations means it will serve Condorrat (Etive Drive and Main Road) and Mollinsburn, and then run non-stop from Mollins Interchange via the M80/M8 into Glasgow city centre.
Service X36 will continue to operate every 30 minutes during the day on Mondays to Saturdays, and every 60 minutes during the day on Sundays.
The nightly evening service will reduce in frequency from 60 to 90 minutes, however the timetable has been extended to offer later journeys from Glasgow to Stirling, including a new late-night departure at 2330 from Glasgow on Mondays to Saturdays.
The route of the X37 service from Falkirk to Glasgow via Cumbernauld Village and Cumbernauld Town Centre remains unchanged, however the daily frequency will revert back to hourly following insufficient demand to support the cost of running the route on a half-hourly basis.
For passengers located along the sections of the route between Falkirk and Bonnybridge, and between Condorrat and Crow Wood, services X35 and X37 will offer a half-hourly service to Falkirk and Glasgow on a combined basis.
First Midland managing director Andrew Jarvis said: “The changes to these services are based on customer feedback, so I hope the public get behind them to ensure their commercial viability going forward.”
For more information visit www.firstgroup.com/south-east-and-central-scotland.