Engineering and construction group Costain has been appointed to assist with a roadworks programme in the Midlands arising from the government's fiscal stimulus plan.The work, which will be undertaken with the aggregates group Lafarge, will have a value of up to £250m over two years.'This framework appointment further strengthens Costain's position as a market leader in highways maintenance in the UK and supports our near-term visibility of forward earnings,' chief executive Andrew Wyllie said.