Terrace Motorway Tunnel facts for kids
| Overview | |
|---|---|
| Location | Wellington City, Wellington, New Zealand |
| Route | State Highway 1 (Wellington Urban Motorway) |
| Operation | |
| Owner | NZ Transport Agency |
| Operator | New Zealand Transport Agency |
| Technical | |
| Length | 460 metres (1,510 ft) |
| Number of lanes | Three (two northbound, one southbound) |
| Operating speed | 70 km/h (43 mph) |
| Tunnel clearance | 26 ft (7.9 m) |
| Width | 42 ft (13 m) |
The Terrace Tunnel is a road tunnel in Wellington, New Zealand. It's part of the main highway, SH1, and goes under a street called The Terrace. This tunnel opened in 1978 and is about 460 metres long. It helps cars travel through central Wellington.
Contents
How the Tunnel Works
The Terrace Tunnel has three lanes for traffic. Two lanes go north, and one lane goes south. This design can sometimes cause traffic jams, especially when many cars are on the road during busy times. However, traffic flow has improved in the southern part of the tunnel since the Wellington Inner City Bypass opened.
This tunnel is one of the few places on a New Zealand motorway where traffic going in opposite directions is not separated by a barrier. Instead, there are double lines and small posts to keep cars apart.
Tunnel's Original Plans
When the tunnel was first planned, it was meant to be part of a bigger motorway extension. Engineers thought there would be a second, parallel tunnel just for southbound traffic. The existing tunnel would then only be for northbound cars. The motorway was also planned to extend all the way to the Mount Victoria Tunnel, which would also have been duplicated.
However, these plans changed in the early 1970s. Building the first tunnel became very expensive, so the idea of a second tunnel was put on hold. This also meant the motorway extension beyond Willis Street was stopped. You can still see some of the pillars and parts of the road that were built for the second tunnel. They are near the cable car line and are now part of the Clifton Terrace car park.
There have been ideas to use a reversible lane system, like the one on the Auckland Harbour Bridge. This means the number of lanes for each direction could change depending on traffic. But safety concerns have been raised about this idea for the Terrace Tunnel.
One interesting fact about the tunnel is that it curves in the middle. This means you can't see the other end when you enter!
State Highway Changes
When the Terrace Tunnel first opened in 1978, it was part of State Highway 2. Later, in 1984, SH1 was connected to the motorway. In 1996, the SH1 route was extended to cover the entire journey from the end of the Wellington Urban Motorway all the way to Wellington International Airport. Since 2007, this route includes the Wellington Inner City Bypass.
Upgrades and Safety
To keep the tunnel working well and safe, the NZ Transport Agency (NZTA) has upgraded many of its systems. This included improving the fire fighting, lighting, ventilation, and drainage systems. They also built new control buildings and made the tunnel safer in case of an earthquake. These upgrades finished in 2012 and help the Terrace Tunnel last longer.
The upgrade work was done by a group called the Wellington Tunnels Alliance. This group included companies like Leighton Contractors, SKM, AECOM, and the NZTA.
Future Plans
The NZTA is always looking at how to improve transport in the area, and the Terrace Tunnel is part of these studies. They are currently looking into the possibility of building a second tunnel in the future.
