In response to a population boom in Sydney's western suburbs, the
Government of New South Wales' Sydney Orbital Roads Strategy identified the need for a limited access north-south link. The Westlink M7 project would connect the three existing east-west motorways: the
M5 South Western Motorway, the
M4 Western Motorway and the
M2 Hills Motorway catering for up to 60,000 vehicles per day and providing faster routes to the
Sydney central business district. Following a
request for tender in 2001, a joint venture between engineering firms
Leighton Contractors and
Abigroup were awarded the contract in 2003 to design and construct the
Westlink M7 motorway and interchanges, including Australia's first complete four-level
stack interchange. Construction of the Light Horse Interchange began in 2003 at the site of the existing M4 Wallgrove Road exit. The new motorway overpass consisted of two spans, and carrying the main carriageways of the M7 over the existing M4. 802 individual bridge segments were used to create the main spans, 8 connecting ramps and a separate bridge carrying a shared pedestrian and cycle path. The Wallgrove Road M4 overpass was retained, with new ramp
flyovers reaching a height of above the existing roadway and ramps. Due to the complexity of the interchange no access to the M7 was provided. During the construction phase between 2003 and 2005, both the
M4 Western Motorway and Wallgrove Road continued to carry traffic as normal. This required the use of balanced
cantilever construction methods to position
pre-cast concrete bridge segments at heights of up to above the active motorway. Upon completion, electronic tolling was implemented for vehicles entering the
Westlink M7, allowing continuous flow of traffic. ==Landscaping==