The contractor confirmed results are due to be in line with expectations as it revealed a record order book of £4.2bn.
The update comes ahead of results for the year ended 31 December 2018 which are due on March 6.
Costain said it made “further progress on its strategy of transforming Costain into the UK’s leading smart infrastructure solutions company.”
It added: “Costain is differentiating itself through its long-term strategic relationships and integrated technology-enabled services necessitated by the increasingly complex and fast-changing nature of its clients’ requirements.
“The Group continues to be involved in a number of major regulatory-driven procurement processes.”
Costain finished last year with an order book at a record level of £4.2bn compared to £3.9bn last time.
It said target clients “are consolidating their supply chains to deliver increasingly large, multi-billion pound investment programmes underpinned by regulatory commitments.”
Costain is also preferred bidder on £600m worth of work compared to £400m last time.
Costain finished the year with a net cash position of over £110m which was down on the previous year’s figure of £177.7m.
Throughout the year the group had a positive net cash position with an average month-end net cash balance of £77m down from £96.7m.
Andrew Wyllie, chief executive, said: “This has been another year of progress for Costain.
“The benefits of our integrated offering, long-term strategic relationships with our clients and strong balance sheet position us well for the future and the significant opportunity we see across our rapidly-changing end markets.”