Helicopter aids in Beauly-Denny line work
Transmission lines are being strung along a major section of the upgraded Beauly to Denny power line.
The lines are being installed on a section stretching from Fort Augustus to Laggan.
A helicopter has been brought in to complete the work across the Corrieyairack Pass.
Last summer, the first section of the revamped line was switched on two-and-a-half years after the project was given the go-ahead.
Beauly to Fort Augustus was the first part of the 137-mile (220km) transmission circuit to be electrified.
The upgraded 400,000 volt line triples the capacity of the existing system.
Six hundred new towers are being built - a reduction of 200 on the existing number. However, some towers are taller and reach heights of 65m (213ft).
Opponents to the upgrade have complained that the new towers will spoil mountain landscapes.
The project is estimated to cost £600m.
Construction manager for Scottish Hydro Electric Transmission, Alistair MacEarchern, said an upgraded line was a "requirement of modern living".
He said: "This is an infrastructure improvement the same as it would be if a road becomes too busy - we upgrade the road.
"We need more power, we need more generating and we need more wire to carry it."
Roy Tilden Wright, from Laggan, led a campaign opposing the erection of large electricity towers.
He said: "We need to balance the needs of renewables, which are clearly proper and right, the needs of supplying the nation with electricity against the unique asset of what the Highlands have to offer."
He said the landscape was being changed for "good and significantly".