Road and rail haulier Stobart Group reported satisfactory progress in all its divisions, but warned of flat passenger numbers in its airport business in the second half.Stobart, which has a 49% stake in the iconic road haulage business known for its green-liveried trucks, said biomass tonnages in its energy division had risen by more than half and passenger numbers in its airport business lifted by a fifth in the last six months.However, the group said profit per biomass tonne overall was lower as margins took a hit from a higher proportion of exported products in readiness for UK plants coming on stream.Transport profits also fell year-on-year following the ending of a contract on 28 February.Stobart, which owns Southend airport in Essex, said passenger-related revenue in aviation was up more than 10% year-on-year, which had lifted underlying earnings.But it added: "Based on known traffic, passenger numbers may be flat in the next six months but we are actively working with operators to identify opportunities to bring further traffic into that period."Its infrastructure business was targeting financial close for investment in two large combined heat and power energy plants in the next six months. It also sold four properties in the period to date, realising £12.7m of cash."Discussions are on-going around potential future disposals and we are hoping to realise at least a similar level of cash in the second half," it said.The rail division increased revenue from external customers by around 40% in the period to 31 July, securing a promising level of work at respectable margins, through collaborations with contractors to Network Rail.That partially compensated for the lower internal development work in the first half, but it expects internal work to pick up in the second half, while there was also strong interest for rail engineering work in the next six months.Stobart's investment division, which includes road haulier Eddie Stobart, of which the group owns 49%, matched management's expectations, although its recorded share of profit would face transaction accounting fair value adjustments.Growth continued in the aircraft leasing business, in which the group has a 33% stake. Its eighth aircraft has been delivered and all aircraft are flying.PW