Two Irish engineers with railway experience, William Doyne assisted by Abraham Fitzgibbon, were engaged by the directors to manage the construction of the line.
They arrived in Nelson along with the Fitzgibbon's family on 18 July 1860.

They quickly dismissed Hacket's proposal and agreed that a better route to Wooded Peak was to be had through the Brook Valley.
This change in plans was not well received by the committee that had been appointed to study the proposal as submitted for the accompanying legislation, which was accordingly withdrawn by the company.

The earthworks for the 5.8-kilometre (3.6 mi) long section between the mines and the Wairoa Saddle were put out to tender in 1861 and awarded the following February to contractors Charles Ambler, John Davis and Robert Carter, each working on approximately equal lengths.
The work included a 1.8-metre (5 ft 11 in) wide ledge in the side of Wooded Peak, drainage and six bridges.

The route of the next 11-kilometre (6.8 mi) section from Brook Street to the Wairoa Saddle was debated amongst the engineers, but they eventually settled on a gradient of 1:18 for the first 8 kilometres (5.0 mi) with the rest at 1:20.
This was divided into seven sections that were put to tender and let on 3 June 1861 to, amongst others, the contractors Hale, Vercoe and party; John Ward and John Mitchell; John Brown and George Cummins; and W. Martin and John Avery.

The company advertised for a supply of 20,000 sleepers after rejecting a trial in which sleepers had been cut from trees adjoining the rail formation.
The price they were quoted in response was £1 per hundred more than the price they had earlier received for sleepers supplied from their own land, but having spent two months on the tender process they decided to proceed with the tenders received from the sawmills.
Approximately 24,000 sleepers were required.

On 17 August the Act authorising the construction of the railway on public lands was passed.
It was based on earlier bills from the Provincial Council and one of 1860 which was withdrawn over the issue of the route of the line.

The act allowed the company to begin construction of the line from the incline section through Nelson, following Brook, Tasman, Manuka, Alton, Hardy, and Rutherford Streets, and along the shoreline on Haven Road to the port.
Three contracts for this section were let in late August 1861 to contractors Mark Blythe and Robert Carter.
Work on the town section was completed within four months.

At around the same time work commenced on the formation between the incline and the port, Dudderidge Gibbs submitted a successful tender for track laying work on the incline section.
This work started on 4 September 1861, but it was soon clear that it would not be completed by the end of the year as expected.
Eager to begin revenue traffic on the line, the company dismissed Gibbs despite his protestations, and continued the work itself on 23 September.

The final shipment of rails arrived on 25 October 1861, numbering 2,314, including 26 casks of bolts.
The last rail was laid in January 1862.
Two Irish engineers with railway experience, William Doyne assisted by Abraham Fitzgibbon, were engaged by the directors to manage the construction of the line. They arrived in Nelson along with the Fitzgibbon's family on 18 July 1860. 
They quickly dismissed Hacket's proposal and agreed that a better route to Wooded Peak was to be had through the Brook Valley. This change in plans was not well received by the committee that had been appointed to study the proposal as submitted for the accompanying legislation, which was accordingly withdrawn by the company.
The earthworks for the 5.8-kilometre (3.6 mi) long section between the mines and the Wairoa Saddle were put out to tender in 1861 and awarded the following February to contractors Charles Ambler, John Davis and Robert Carter, each working on approximately equal lengths. The work included a 1.8-metre (5 ft 11 in) wide ledge in the side of Wooded Peak, drainage and six bridges.
The route of the next 11-kilometre (6.8 mi) section from Brook Street to the Wairoa Saddle was debated amongst the engineers, but they eventually settled on a gradient of 1:18 for the first 8 kilometres (5.0 mi) with the rest at 1:20. This was divided into seven sections that were put to tender and let on 3 June 1861 to, amongst others, the contractors Hale, Vercoe and party; John Ward and John Mitchell; John Brown and George Cummins; and W. Martin and John Avery.
The company advertised for a supply of 20,000 sleepers after rejecting a trial in which sleepers had been cut from trees adjoining the rail formation. The price they were quoted in response was £1 per hundred more than the price they had earlier received for sleepers supplied from their own land, but having spent two months on the tender process they decided to proceed with the tenders received from the sawmills. Approximately 24,000 sleepers were required.
On 17 August the Act authorising the construction of the railway on public lands was passed. It was based on earlier bills from the Provincial Council and one of 1860 which was withdrawn over the issue of the route of the line.
The act allowed the company to begin construction of the line from the incline section through Nelson, following Brook, Tasman, Manuka, Alton, Hardy, and Rutherford Streets, and along the shoreline on Haven Road to the port. Three contracts for this section were let in late August 1861 to contractors Mark Blythe and Robert Carter. Work on the town section was completed within four months.
At around the same time work commenced on the formation between the incline and the port, Dudderidge Gibbs submitted a successful tender for track laying work on the incline section. This work started on 4 September 1861, but it was soon clear that it would not be completed by the end of the year as expected. Eager to begin revenue traffic on the line, the company dismissed Gibbs despite his protestations, and continued the work itself on 23 September.
The final shipment of rails arrived on 25 October 1861, numbering 2,314, including 26 casks of bolts. The last rail was laid in January 1862.
Dun Mountain Railway