Kier Group said on Tuesday that the underlying trading performance for all four of its divisions for the year to 30 June 2015 has remained in line with management's expectations.Following the completion of the acquisition of MRBL Ltd (Mouchel) on 8 June, and as a result of continued underlying organic growth, the total order book for the enlarged group has been maintained at £9.3bn at 31 May, excluding potential further renewals and extensions valued at up to £2bn.Kier said the integration of Mouchel's operations was progressing well with the smooth transition of operational management and with synergies on track.Read more: Kier Group completes acquisition of Mouchel "Following the acquisition of Mouchel, Kier is now the sector leader in a growing UK highways maintenance and management market," said the company. "In particular, the acquisition enables Kier to capitalise on £17bn of investment in the strategic road network to be delivered through Highways England over the next five years."The company said the performance of the property division continues to be strong, with a pipeline of opportunities in excess of £1bn. The division has exceeded its minimum requirement of 15% return on capital employed, with the average capital invested over the year being approximately £75m, said Kier.Kier said the number of completions within the residential division for the year to 30 June 2015 across the private housing and mixed-tenure businesses is expected to be approximately 2,100 units.It added that the construction division has experienced significant year-on-year organic growth, with margins in line with management's expectations at around 2%.Second-half revenues in the services division have increased following the awards of a £200m four-year extension of the highways services contract with Northamptonshire County Council and more than £700m of awards as part of the AMP6 cycle.Shares closed up 0.1% at 1,433p on Monday.