The pupils and mentors enjoyed a behind-the-scenes tour of works on the bypass of the New England Highway, ahead of the planned installation of the project's final girder next week.

Upper Hunter MP Michael Johnsen said youngsters from Scone High, Scone Grammar and Scone Public schools were given a briefing on the construction of the Parsons Gully Bridge.

"The students were able to see a 500-tonne mobile crane in action and had the chance to ask questions compiled in their classes at school," he explained.

"Already 96 of the Parsons Gully Bridge girders have now been installed, with spans now bridging Kingdon and Liverpool streets.

"Once complete the bridge will be a 540m long key component of the bypass, and will use 124 girders, each of which are 27 metres long and weigh 45 tonnes."

Scone Public School principal Deborah Fisher said students were intrigued by the bypass and discussions about it had generated "plenty of questions and ideas".

"It's an enormous project of great technical complexity and seeing it up close is an additional stimulant for these hungry young minds," she added.

"STEM (science, technology, engineering and mathematics) subjects are a priority in today's education environment and teachers are very aware of the importance of guiding students with potential to develop these skills, so to be able to demonstrate the career possibilities in these sectors is invaluable.

"There are also great opportunities in infrastructure for trades and business, so a project like the Scone Bypass appeals to a broad cross-section of the school population."

The New England Highway is a major freight and commuter route, which forms part of the Sydney to Brisbane corridor of the National Land Transport Network and is the primary thoroughfare connecting the Upper Hunter with Maitland and Newcastle.

The Scone Bypass will remove about 500 heavy vehicles per day from Kelly Street, which will improve local traffic flow and road safety, and will reduce travel times for freight.