Mace director Tim Renwick said the PLA was analysing proposals for the assembly of the wheel before it grants a river works licence and had raised a number of concerns in a letter to the firm.
The authority is worried because the wheel will jut 110 m into the Thames – almost halfway across it. This would make it difficult for craft to use the central navigation channel.
In its letter, the PLA said it feared craft would find it difficult to pass under Westminster and Hungerford bridges at high tide because they would have to use lower arches away from the centre of the river.
It is also concerned that pleasure craft that usually swing round to dock at Westminster Pier would find that the wheel prevented them from doing this. The PLA would also prefer a shorter construction programme.
Mace is proposing three solutions to meet these concerns: to provide a tug boat to help craft dock at Westminster Pier, to put traffic lights on Westminster and Hungerford bridges, so that boats would queue to pass under the higher arches, and to shorten the assembly schedule.
It will also construct piling and welding sections of the wheel simultaneously. It had proposed to insert the piling for the wheel before assembling the six sections and adding cables.
"I wouldn't have been surprised if there were more issues," Renwick said of the PLA's concerns. "I think these measures are very reasonable." The wheel is designed by architects David Marks and Julia Barfield. The project is sponsored by British Airways.
