Problem to be addressed
Demand on the M4 Motorway in Sydney routinely exceeds capacity during peak periods, resulting in congestion and travel delays. Transport modelling undertaken for the 2015 Australian Infrastructure Audit noted that the corridor had a volume to capacity ratio of 1.1 in 2011 for both morning and afternoon peaks.
Greater Western Sydney currently accounts for almost 10% of Australia’s population, and the M4 provides the area with an important east–west connection. The population of the main M4 catchment area is expected to grow by 44.5% (around 490,000 people) between 2011 and 2031. Nearby developments, such as the Western Sydney Airport at Badgerys Creek and the Western Sydney Employment Area, will also add to the demand on the corridor. Without action, the impact of the current capacity constraint will increase over time.
The project covers a range of measures aimed at making better use of the existing M4 infrastructure and increasing capacity along a 35 km section of the M4 between Mays Hill (near Parramatta) and Lapstone at the base of the Blue Mountains.
The ‘better use’ components include:
- the introduction of Intelligent Transport System measures, including ramp signals, vehicle detection devices and electronic signage
- upgrades to entry and exit ramps
- new freight bypass lanes at three entry ramps – westbound at the M7 and the Prospect Highway, and eastbound at Roper Road, Colyton – which would give priority to trucks and improve merging onto the motorway
- a new communications and power ‘backbone’ along the motorway.
The project also includes the construction of an additional lane in each direction in the median along a 4.3 km section of the motorway, between the Roper Road and M7 interchanges. This widening was completed in 2019.
Economic, social and environmental value
Economic benefits of the project include shorter travel times, improved travel-time reliability and road safety, and increased journey opportunities, all of which will boost productivity. Other benefits include reduced vehicle emissions, and real-time information on road conditions to allow better journey decision making for drivers.
The proponent’s stated benefit-cost ratio is 5.3, with a net present value of $2,640 million (7% real discount rate).
Capital cost of initiative as stated by proponent (2015 business case) $853 million (P90, nominal, undiscounted) | Australian Government contribution $60 million through the Asset Recycling Initiative | State government contribution $540 million