The move will see 132 people now enter a 90-day redundancy consultation process.
McAlpine has created expanded regions in the North and the South to complement its existing London region and Civils and Infrastructure business.
It will also focus more on major projects in key sectors including Civil Infrastructure, Healthcare, Commercial Offices, Residential, Leisure and Heritage.
Chief Executive, Paul Hamer, said: “I am immensely proud to work alongside the talented people of Sir Robert McAlpine who have all been through a great deal over recent months supporting our business in the face of the Covid-19 challenges.
“Whilst we are seeking to do our best by our people, in the coming months we are compelled to make some very difficult decisions.
“This will unfortunately result in a redundancy process and this loss will be keenly felt within the business.
“The changes are aimed at enhancing the long-term resilience and sustainability of our business rather than short-term cost cutting.
“We have a proud record of success in the UK for the delivery of major projects and continue to work in partnership with our clients who see the value that Sir Robert McAlpine offers as a true engineer and builder.
“As we look forward, our refined structure is set to create greater focus and agility, allowing us to deliver improved value to our clients through innovation and technical excellence.
“We have already established robust foundations for our next 150 years and we firmly intend to realise our vision of ‘Proudly Building Britain’s Future Heritage’.”