Prior to the 2011 Canterbury earthquakes the township of Lyttelton and Lyttelton Port (the largest port in the South Island) were serviced primarily by the Lyttelton Tunnel. Sumner Road provided the designated regional lifeline route and was used for the movement of hazardous goods and overweight and over-sized vehicles between Christchurch and Lyttelton.
Sumner Road has been closed since the earthquakes due to an unacceptable risk of further rock fall. In the absence of this route, temporary arrangements have been made to enable hazardous goods to be transported through Lyttelton Tunnel (requiring short-term tunnel closures), while overweight and over-sized vehicles are required to use alternative routes, particularly Gebbies Pass to the south. While these temporary arrangements have performed well in the aftermath of the earthquakes, they are not considered appropriate long-term options for servicing Lyttelton and the Port.
Carrying hazardous goods through Lyttelton Tunnel increases the risk of fire. Due to the challenges of fighting a fire in the tunnel there is a risk that, even with deluge systems, a fire could cause significant damage resulting in an extended tunnel closure and up to two years’ repair time. The need to maintain 24/7 access post-earthquake has limited the ability to undertake routine maintenance work in the tunnel.
In the event that Lyttelton Tunnel is closed for any reason, Gebbies Pass would need to carry the majority of freight between Christchurch and Lyttelton. However, Gebbies Pass Road was not constructed to handle these freight volumes and currently has sub-optimal road geometry and pavement construction. It also has a degree of vulnerability to geo-hazards (particularly rock fall and landslips). The Gebbies Pass route is also significantly longer for journeys from central Christchurch to Lyttelton – 52km compared to 18km via Sumner Road.
The closure of Sumner Road has also created a network resilience issue for the community of Sumner. It is now heavily reliant on the Main Road route to the city, which is also vulnerable to further landslips.
Overall the closure of the Sumner Road route is estimated to have resulted in over $30,000 per month of additional transport operating and time costs. It is estimated that a future medium- to long-term closure of Lyttelton Tunnel requiring the re-routing of freight traffic over Gebbies Pass would incur a travel cost penalty of some $396,000 per day or $12m per month.
So what is planned?
