Construction information specialist Glenigan has the list of bidders as Balfour Beatty, Vinci, Skanska, Ferrovial and Graham Construction.
The local council confirmed in February that a short list had been drawn-up for the scheme after the Department for Transport confirmed a £82.5m grant towards the cost of the project.
A winner is due to be chosen this summer ahead of work starting on site before the end of the year with a preliminary completion date of early 2015.