Nevertheless the depressed state of the money market meant that the scheme lay dormant until a further Act was obtained on 1 August 1870, sanctioning a second extension of time, and vesting the undertaking jointly in the GNR and L&YR. The concern was then renamed the Halifax and Ovenden Joint Railway. Soon afterwards, construction began from a junction with the L&YR at the north end of Halifax station, for to . The steepest gradient was 1 in 45 and the sharpest curve was radius. A masonry viaduct carried the line through Halifax, with 35 spans which varied from . A short distance beyond that, the line crossed another viaduct of 11 spans which varied from . There were two tunnels, North Bridge () and Lee Bank (). Earthworks were heavy, with high retaining walls. Goods depots were opened at North Bridge and Holmfield. The line opened for goods between Halifax and on 17 August 1874, to Holmfield on 1 September 1874, and was opened to passengers throughout on 1 December 1879. Thornton, West Yorkshire was an important industrial centre, and in 1865 separate proposals were advanced by the L&YR and the GNR for lines to Thornton, but they were rejected by Parliament. During 1870 local businessmen put forward a scheme for a railway from Bradford to Thornton via Clayton and Queensbury; this would connect industrial locations hitherto not served by railways. The project had already been cut back in scope from an earlier project to reach Keighley, on the grounds that such a line would be unaffordable, due to the difficult terrain. The GNR agreed to sponsor the reduced scheme and subscribe half the capital; the GNR was partly motivated by the belief that the rival Midland Railway would step in, getting access to Halifax, if the GNR held back. Accordingly the Bradford and Thornton Railway Act was passed on 24 July 1871, sponsored by the GNR, and the undertaking was transferred to and vested in the GNR by Act of 18 July 1872. The authorised construction was of line between St Dunstan's, Bradford, and Thornton. The junction at St Dunstan's was to be a triangle joining the existing GNR connecting line between Hammerton Street Junction and the Mill Lane Junction, approaching the L&YR Exchange station: this would allow direct running towards the L&YR station and also towards Laisterdyke and Leeds. (There were to be no platforms on this west-to-east side of the triangle.) In addition there was to be a short branch to Brick Lane, on the west side of Bradford, where a goods station was to be established, named City Road.