HDR undertook the preliminary design and detailed design for an additional lane on a 2.6km section of the northbound carriageway of the Gateway Motorway between Sandgate Road and the Deagon Deviation, including bridge structures at Cabbage Tree Creek and Depot Road. Provisions were also made on the southbound carriageway for the future Gateway Upgrade North (GUN) project including bridge structures, formation widening and drainage infrastructure.

HDR developed all technical elements of the project including geometric alignments, stormwater drainage and flood modelling, bridges, pavement design, sign and pavement marking, geotechnical, lighting, ITS (Managed Motorways), noise, PUP, constructability, and environmental approvals. 

Key challenges included:

• Development of roadway geometry utilising Extended Design Domain (EDD) to suit the existing geometry and budgetary constraints
• Resolving detailed bridge and traffic management constructability staging in conjunction with corridor constraints
• Consideration of structures and staging with poor ground conditions, which dictated the requirement for pre-loading embankments for 4 to 6 months and the use of controlled modulus columns (CMC’s)
• Flooding challenges associated with Cabbage Tree Creek during construction and operational phases