Revenue increased by around 12% despite a round of cost-cutting measures to nearly £370m.
The improved trading and £14m proceeds from the sale of heavy plant also helped to slash net debt from around £100m to £71.4m.
Russell Down, chief executive, said: “These results demonstrate the success of our turnaround plan with significant improvements across all financial and operational performance measures.
“While we have made a solid start to the year, the market remains competitive.
“With the business now stabilised and a strong balance sheet, we are well positioned to take advantage of market opportunities and continue to deliver sustainable profitable growth.”
He added: “Our focus on strong customer relationships has enabled us to win and renew a number of contracts with our larger customers, including a contract renewal, and scope extension with Carillion, which in total could be worth up to £45m over three years, and renewals with Babcock and Morgan Sindall.
“While there is some market uncertainty in the lead up to Brexit and the general election we are now well placed to deliver sustainable profitable growth.”