Holzmann, which was saved from bankruptcy last week by the last-minute intervention of the German chancellor, Gerhard Schroder, owns a 30 per cent stake in Connect Roads, a joint venture with BICC, the construction giant, and WS Atkins, the civil engineer.
The Conservative government awarded the company the contract to build the first private road of any substance since toll roads were phased out in the last century - the upgrading of the A50 from the M1 at Derby to the M6 at Stoke-on-Trent.
The road opened in 1997 under an innovative Private Finance Initiative in which the consortium was paid a small fee for every vehicle that used the road. Enthused by its success, Connect bid for - and won - a similar PFI contract to build the A30/A35 Honiton by-pass, one of the most popular roads for holidaymakers going to Devon and Cornwall.
The road has caused much controversy because of the environmental disruption caused by a change of route taking the road across Exmoor. A group of protesters, including the legendary Swampy, tunnelled under the proposed route, so holding up building work.
Holzmann said last week that it would make up to pounds 1bn in disposals, and the Connect stake is believed to be top of the list. The operation has more than pounds 160m of net assets and a turnover expected to exceed pounds 30m this year. A price tag of up to pounds 50m is anticipated for the holding.
The most likely solution is for one of the other two partners to buy out Holzmann. But BICC, which sold almost all its cable operations to concentrate on Balfour Beatty, its building business, is not flush with cash.
And WS Atkins, which increased its holding in Connect last year, is believed to be looking to dispose of its stake. This leaves the way open for any would-be turnpike owners.