Sunday, 1 November 2009

New Arahura Road-Rail Bridge Nears Completion

The new Arahura road-rail bridge is nearly completed. The bridge replaces the original single lane structure which is the original bridge at this route on the Ross Branch (now the Hokitika Branch) and was a single lane (for road) combined single deck road-rail structure. Being on the same level, the bridge was a hazard to road traffic which had to come to a stop every time a train came along. In turn, trains were limited to 10 km/h in order to minimise the risk to road vehicles, however “cornfield meets” were not unheard of and the rail running through the road deck could be slippery and hazardous, especially for motorcycles.
The new bridge has two lanes for road traffic and one rail track all on a combined substructure. It is therefore a new way of building a combined bridge that is similar to the parallel bridges at Inangahua (one lane of road traffic and one rail line) and Napier-Westshore (two lanes of road traffic and one rail line). The road portion of the latter closed some years ago although the deck is still in place. The new bridge at Arahura was constructed by first building one of the road lanes to the north of the existing bridge, and diverting road traffic onto it. The rail structure was then built on the south side, and its piers can be seen in this photo. The rail bridge was then built, and the original wooden bridge, now sandwiched, was closed and demolished. The second lane of the road bridge was then built in place of the original bridge. There is now one lane of road traffic open while the second bridge is completed. The whole project is due to be completed by early 2010.
This photo is by Russ, you can see it at full size by clicking on the link. It shows a train crossing on the original bridge, sandwiched by the opened lane of road bridge on the far side, and the substructure of the new rail bridge under construction on the near side. The new rail bridge was opened early September and the entire original bridge has now been demolished.

Originally uploaded by > Russ<
This is one of my old photos of the bridge which was taken in 1987. Click on it to go to the album, which shows other road rail bridges as well as pages of a historical article I wrote some years ago.
This is a picture of the parallel bridge over the Inangahua River, built in the 1920s. Since the road closed on the Westshore bridge just north of Napier, that bridge will probably be rebuilt eventually as rail only and its historical features will disappear. Hence the bridge at Inangahua has been the only parallel road rail bridge in NZ until this one has been built at Arahura.
Here is my map of the Arahura Bridge area, it shows quite a few changes. The highway on the west of the bridge has been changed twice. The first highway used to go out with two right angle bends and then over a bridge across the railway line. This was closed sometime 1990s I think and the highway was then put on the south side of the railway track. (You wonder why this wasn’t done instead of building the overbridge because the sharp bends would have made it unsafe for traffic) Now, the highway will be on the north side again for a short stretch until it crosses the railway line at a roundabout which is like the one at Kumara Junction. Then it will follow the more recent alignment south-west to Kaihinu.

View Larger Map
Whilst the new bridge is great for road users, compared to the original it is hideously ugly and reflects that outside of major centres, bridges are functional utilitarian designs that are no longer considered as public architectural works. In time, the bare ground will be landscaped and planted to beautify the immediate surrounds. A span of the old bridge has been preserved in a reserve nearby as a nod to its superior aesthetic qualities.