* Six-month net profit was A$80.94 million
* U.S. roads contributing to flat earnings
* Toll revenue up 13.1 percent to A$556 million (Adds details on Queensland plans, CEO and analyst comments)
By Byron Kaye
SYDNEY, Feb 13 (Reuters) - Transurban Group, Australia's biggest toll road operator, said on Thursday it may consider buying Queensland state's troubled AirportlinkM7 from receivers if a bid to buy the government's Queensland Motorways Ltd (QML) succeeds.
Transurban, superannuation fund conglomerate AustralianSuper and state-run Abu Dhabi Investment Authority are one of three groups to file indicative bids with the Queensland government for QML, a deal analysts say will fetch about A$5 billion ($4.52 billion).
"We don't want to preempt what the receiver might do there, but I would imagine we'd take a look at it", Transurban chief executive Scott Charlton told journalists when asked if Transurban would buy AirportlinkM7 if it took over QML.
Transurban, which already has roads in Victoria and New South Wales, as well as in the U.S. state of Virginia, is seeking to strike a balance between acquiring new assets before long-term road licences expire and growing stockholder distribution in the short term through toll increases and technology improvements.
"Their toll roads run out after a certain amount of time so they've continually got to find new assets," said Morningstar analyst Adrian Atkins. "They've always got to be looking or something (but) I don't think that many investors actually think about it, they're just looking for today's dividends."
On Wednesday, Transurban learned it was the preferred bidder for Sydney's Cross City Tunnel for about A$500 million. The company also expects to get final approval from the New South Wales government to build a link between Sydney's M1 and M2 motorways in late 2014, Charlton told reporters.
U.S. SLUGGISH, PROFIT FLAT
Transurban posted a small decline in first-half net profit as maintenance and tolling system costs on its existing roads weighed down a substantial lift in toll revenue.
Net profit for the six months ending December 2013 was A$80.94 million, a 0.25 percent decline from A$81.1 million in the same period a year ago.
Analysts had expected the company to boost its interim profit from stronger traffic volume after finishing its upgrade to its Hills M2 toll road in Sydney.
Transurban said the result was hit by the cost of running its 495 Express Lanes in Virginia which opened in November 2012, by the cost of building new roads to connect the 495 to other roads, and by higher overall maintenance costs.
The 495, which opened midway through the previous comparable period, had a 249.2 percent increase in average daily toll revenue, but that road's traffic and revenue "remains below the project case expectations", Transurban said.
"A review of the project has been completed which resulted in downward adjustments to traffic and revenue projections," the company said.
The company highlighted a substantial increase in what it says is its most accurate performance measure, toll revenue, which was up 13.1 percent to A$556 million in the half year.
The biggest toll revenue contributor was Melbourne's CityLink road, which increased revenue by 10 percent to A$269.25 million despite a traffic rise of only 2.1 percent because a tolling system upgrade led to "improvements in recovery rates", Transurban said.
The company's free cash, a key measure for analysts to measure the company's cash generation, rose 24.5 percent to A$239.97 million.
The company said it would pay investors an interim distribution of A$0.17 per share and said it would increase its full year distribution from A$0.34 to $0.35. Transurban shares were about 1 percent higher in a flat overall market.
($1 = 1.1070 Australian dollars)