The M&BR and SA&MR opened the jointly owned
Store Street station in Manchester on 10 May 1842. The initial opening of a single line only proved impossibly constraining, and installation of double track was ordered early in 1842, together with construction on from Godley to
Glossop. The line from Godley to was opened on 10 December 1842, and on to a "Glossop" station, later to be renamed , on 24 December 1842. There were six daily trains to Glossop supplemented by four to
Newton & Hyde station. There were four to Glossop on Sundays. By November 1842 the stations were Manchester (Store Street),
Ardwick,
Gorton,
Fairfield,
Ashton,
Dukinfield,
Newton & Hyde,
Broadbottom and
Glossop. The Dukinfield station (called Dog Lane) was closed in 1845; another station, named simply was opened nearby in 1846, closing in 1847. There was also a Dukinfield station on the Stalybridge branch. The main line was opened as far as Woodhead in 1844, with stations at
Hadfield and
Woodhead. Construction of Woodhead Tunnel was the next hurdle, but improved pumping machinery had been installed, enabling better progress. Alliances and extensions of the network were in the minds of the directors. Encouragement was offered to a proposed
Sheffield and Lincolnshire Junction Railway, to run from the SA&MR at Sheffield to
Gainsborough. At the same time (1844) friendly relations with the Manchester and Birmingham Railway were further developed, and at length this led to a proposal by the M&BR with the
Midland Railway to lease the SA&MR, giving those companies better access to Manchester. This seemed to be going well, and an authorising Act was passed, but the proposal was voted down in May 1845 by shareholders, who were persuaded that their line would be merely a remote satellite of the Midland Railway. A branch line was being built from Ashton to . However disaster took place: on 19 April 1845 a nine-arch viaduct under construction collapsed: 17 workmen were killed. On 9 June 1845 a short single line branch to was opened; powers were obtained in the 1846 parliamentary session to take it over from
the Duke of Norfolk, who had caused it to be built. The branch joined the main line facing Manchester some distance to the east of the original Glossop station, now renamed Dinting. Finally on 22 December 1845 Woodhead Tunnel was ready and a ceremonial opening of the entire line, including the Stalybridge branch, took place; the following day it opened to the general public. The tunnel was at the time the longest in the country, at . Two extra stations were added at the site of previous coal sidings at and at . Besides Woodhead, there were short tunnels at Audenshaw Road, Hattersley (two),
Thurgoland and Bridgehouses. Among the bridges the two most notable were the
Etherow Viaduct and the
Dinting Viaduct, the latter with five central and eleven approach arches. The completed network consisted of of main line, on the Stalybridge branch and on the Glossop branch. ==1845: Expansion==