Construction of the two underpasses has involved building temporary roads to their sides. Sheet piled retaining walls have been capped with reinforced concrete decks over which new track is already being laid.
Close attention has been paid to making the ground and turf conditions over the underpasses identical to the rest of the course. 'We didn't want any heavy sections, ' notes Buro Happold civils group director Andy Murdoch.
Track make-up, from grass down, consists of a growing medium underlain by sand, filter drainage, a blinding layer and a geotextile membrane.
Earthworks are being carried out in tandem with other construction. To get levels on the track to desired tolerances - there is a slight climb to the finish line - earthmoving plant was guided by laser and GPS.