Sydney’s M4 Tunnel Reopened After Sandstone Exposure Forced Closure
Sydney’s M4 tunnel reopened on Monday after being shut down for over 12 hours due to exposed sandstone, prompting questions about the tunnel’s maintenance and the use of ‘shotcrete’ in it’s construction. The closure caused meaningful traffic delays across the city, impacting morning commutes and raising concerns about the long-term integrity of the vital transport link.
The incident underscores the ongoing challenges of maintaining Sydney’s extensive toll road network, largely controlled by Transurban, and highlights the complexities of balancing infrastructure upkeep with minimizing disruption to motorists. While the immediate risk was deemed low, the event reignites debate around tolling fairness and the pace of negotiations between the NSW government and Transurban to simplify the state’s tolling system.
Transurban closed a section of the M4 after discovering exposed sandstone during routine overnight inspections.According to a statement, safety is the company’s “number one priority,” and overnight operations secured a “small section” of the affected roof. The exposed sandstone, Vimonsatit explained, posed a low risk due to the “localised and small area” affected.
The repair process involves applying shotcrete – a pneumatically applied concrete – to reinforce the sandstone. Transurban stated that new shotcreting of the removed area will occur at a later date. Shotcrete is commonly used in tunnel construction to stabilize rock formations and provide structural support.
Motorists affected by the closure have been advised to seek refunds through the Linkt app, the same system used for the recently implemented $60 toll cap. However, some, including MP John Aitchison, argue Transurban should proactively refund all impacted users across its entire network, including the M5 and M8.
The incident also sparked discussion about the potential for improved traffic monitoring. According to Collins, Transurban’s tolling infrastructure provides Transport for NSW with detailed data on traffic flow – including entry and exit times – which could be used to better understand and manage congestion.
Transurban holds a majority stake in Sydney’s private motorway tolls, and negotiations with the NSW government regarding a unified tolling system are ongoing.The company’s extensive network and the complexities of these negotiations were highlighted in a recent report detailing the slow progress towards a fairer and simpler tolling system for Sydney drivers.
