Huge holes appearing along Palmerston North’s Ferguson St closing some traffic lanes signal the near completion of the city’s electricity supply upgrade.

Powerco has been working on a $27.4 million project for five years to improve supply security after a series of outages blighted the central city in 2016.

The final stages have seen contractor Downer installing larger capacity underground cables between the Ferguson St and Main St substations.

Powerco general manager for electricity Karen Frew said the work would not involve any planned power outages for customers.

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However, motorists on the busy section of roads around the central city would continue to be affected by traffic management restrictions while the work was carried out.

The large hole at the Ferguson St/Fitzherbert Ave intersection was expected to be filled, and the road surface restored by the end of Friday.

The work carried out on the extended project so far has included building the new substation at the corner of Linton St and Ferguson St, and installation of a second transformer there.

A new indoor 33kV switch room was put in at the Linton St substation, and two new underground circuits from there to the Ferguson St substations were connected.

The final stage, expected to start in September, would be taking down the overhead power lines along Main St to the Keith St substation.

Those lines were strung up in September 2016 while underground cables were upgraded.

The Palmerston North City Council, which has encouraged installation of underground power cables for most of the city for many decades, allowed the Main St overhead lines as a “temporary” measure.

That agreement was later extended to support the suite of power supply upgrades to be carried out.

Residents and motorists can keep up to date with Powerco’s project progress at its dedicated webpage.