Engineering group Costain posted a sharp rise in profits in the year to 31 December and said it is confident for the future given the need for the government to invest in infrastructure even as it seeks to cut the deficit.Pre-tax profits jumped by 54% from the previous year to £27.9m on revenues that fell to £1.02bn from £1.06bn. The full-year dividend was upped to 9.25p from 8.25p the previous year.Costain said the decrease in revenues reflects a decision to reduce exposure to health and education."Once again, the group has demonstrated its resilience in a continuing difficult economic environment," said chairman David Allvey. "We are confident that our position in markets underpinned by strategic capital expenditure, regulatory commitment or essential maintenance requirements will continue to stand us in good stead."Costain works on big construction projects such as the St Pancras railway station in London and Crossrail, the railway that will connect regions to the east and west of London.Costain points out that the government last year identified that the country needs £200bn of investment by 2020 and adds that, where savings need to be made, it can help to deliver these."These pressing national needs also have to be weighed against the economic realities of uncertainty, a reduced ability of the public sector to invest, macroeconomic constraints and customers who are increasingly seeking value-driven solutions," the company said."Such a challenging market environment also provides major opportunity for businesses able to create and deliver those solutions."