Engineering firm Costain posted a rise in revenues and profits in the first half, helped by a strong showing in its infrastructure business.Revenue was up 2% on the previous year to £477.9m, while profits rose over 50% to £15.4m.Revenue in the firm's Infrastructure division during the period was up 27% to £279.5m, which offset a fall in both its Environment and Energy & Process arms.Earnings per share were up to 21.2p from 11.9p in the first half of 2011 and shareholders were rewarded with the interim dividend rising for a fifth successive year, by 8% to 3.5p.It also reaffirmed it was on track to meet expectations.Chairman, David Allvey, said the results marked another strong performance with an increase in profit, robust cash balance and a high quality order book comprising both new contract awards and contract extensions. "We now meet the integrated service requirements of major customers, whose repeat orders account for over 90% of the order book and who are continuing to invest in essential infrastructure projects," he said."Despite the ongoing challenging economic conditions, we remain on course to deliver a result for the year in line with the board's expectations."Costain's order book, as at the end of June, was £2.4bn, roughly the same as the year before.This included £850m of revenue secured for 2012, of which 28% is support services related activities. The firm aded that its order book continued to provide good long-term visibility with around £600m of revenue secured for 2013 and in excess of a further £1.4bn of revenue secured for 2014 and beyond.