Mr Hardcastle, of consultants KelloggBrown and Root, said the main recommendation was for an "area-wide" charging scheme which would use satellite technology to monitor the journeys of all motorists and charge them per mile.
Cheney, who was Halliburton's CEO in the 1990s, and nine others were charged with conspiracy and "distribution of gratification to public officials" in a long-running case involving the company and its Kellogg, Brown and Root subsidiary.