The highly successful period from the opening came to and end in the first half of the 1840s, and all the "coal railways" began to think of economies, and of amalgamation. A first step was implemented on 29 March 1845 when the Ballochney Railway, the Slamannan Railway, and the Monkland and Kirkintilloch Railway operated together jointly, with co-ordinated tolls and a single management, referred to as "the Monkland Mineral Lines". The Garnkirk and Glasgow Railway was no longer considered an ally.