Infrastructure contractor Balfour Beatty announced its second contract win of a year that is less than a week old, with news of a five-year extension to its existing arrangement with National Grid.In a deal worth up to £750m, Balfour Beatty will continue maintenance and upgrade work on the UK electricity transmission network. Work involves the ongoing maintenance and refurbishment of overhead transmission lines, as well as designing and delivering National Grid's upgrade plans across the network.Earlier this week, Balfour Beatty said it has been appointed as the preferred bidder for the £800m Essex Waste Partnership's Residual Waste Treatment contract.jh