Work was started on the construction of the Wigan to Preston section of the railway. As Preston stands upon a ridge rising sharply from the north bank of the River Ribble reaching it involved some engineering, the North Union reached its terminus by descending gradients as steep as 1 in 100 to the valley, crossing the river and cutting into the rising ground as far as Fishergate. The river bridge was of five arches, each spanning 120 ft. The line was completed in 1838 and a trial run was held on 22 October with a train running from Wigan to Preston, and the line opened to the public on 31 October 1838.