Following on from last time here is the first of two posts which compare the two existing rail corridors and have a look at the pros and cons of each. The Main South Line corridor originates at Lyttelton and runs through Rolleston on its way to Invercargill. In its 2017 election manifesto, Labour placed on record a funding promise for development of suburban passenger services from Christchurch to Rolleston. I have yet to determine why Rolleston was chosen as at the time, there was considerable local interest in developing the Rangiora corridor and relatively little interest in Rolleston. The practical impact is that the past couple of years has seen the focus go into Rolleston in a questionable and possibly fruitless way.
The various factors that have influenced the historical population distribution of Christchurch City are not something I know anything about, but for many years the Main South Line corridor has tended to be developed more for industrial and very low density population distribution in Christchurch as a whole. This has been accelerated since the 1950s/1960s with some of the housing that used to be close to the corridor through Sockburn, for example, replaced by industry with a particular focus on private siding access. The MSL has had the bulk of rail traffic within Christchurch city limits for decades and for this reason had as many as four tracks in parallel between Christchurch and Islington, two bi-directional shunt lines for freight only and two main lines that were sometimes bi-directional and sometimes uni-directional. From Lyttelton to Christchurch and from Islington to Rolleston the railway was historically equipped with dual uni-directional main lines, except for the Lyttelton Tunnel which has always been single track. From the 1990s with the drop off in rail freight most of the four track sections went down to two main lines, and the Linwood-Addington and Islington-Rolleston sections were singled. In more recent times the “third road” and “fourth road” lines have been reinstated in parts to serve new sidings between Addington and Sockburn due to the development of privately operated freight forwarding services by some of NZ’s largest transport logistics companies.
The 1960 Christchurch Railway Station in Moorhouse Ave was designed from the outset to handle large volumes of suburban passenger traffic, but by the time it opened, this traffic had falled off significantly. The station had six platforms, there being four shorter dock platforms for local trains and the two longer main platforms for long distance trains. The eastern docks were only suitable for trains to Lyttelton and as there was usually only one of these at a time, the other dock was used for freight loading. Western docks would handle the local passenger trains that went north and south. On the Main North Line this was a service to Rangiora that even in the 1940s only ran four times a day in each direction. This was reduced to three trains each way daily in 1956 and once each way in 1967. The service ceased completely in 1976. Passengers could transfer to and from the city tram network at Papanui. MSL local passenger services included a daily return to Ashburton which ceased in 1958, daily returns to Southbridge and Little River until 1951 and the last train going south was the daily return to Burnham Military Camp which finished up in 1967. There was also a mixed (passengers and freight) return service to Springfield on the Midland Line via Rolleston until 1968. The Christchurch-Lyttelton section of the Main South Line corridor had the most frequent services that in the early 1960s amounted to 22 returns daily, hauled by electric locomotives. This was cut back in response to the 1964 opening of the Lyttelton road tunnel with the CTB bus service that competed with the trains, the electric locomotives were taken off the run in 1970 and the entire service ceased in 1972 (Source: “The Country Commuter”, Les Dew, CTB/THS, 1988).
Currently in Christchurch the distribution of urban housing in adjacent proximity to the Main South Line corridor is confined to the following areas: Lyttelton to Heathcote, Opawa, pockets of Addington, pockets of Sockburn, Islington, Templeton and Rolleston. In some of these areas, residential housing that was once closer to the railway has been displaced by newer industrial development. This means the population that can be usefully serviced by suburban passenger trains is limited, and in reality that has scarcely been any different over the whole history of Christchurch. Because of the large scale and long term entrenchment of industrial development along this corridor, it would be difficult to displace much of the existing industrial development in the City in favour of residential housing, and west of Islington the only area of expansion is to the south and west of Rolleston as noted in the previous post. Even if we exclude Christchurch to Lyttelton and only focus on Christchurch to Rolleston, the options are still limited. Present intensification priorities for inner suburbs in Christchurch adjacent to this rail corridor could be expected to impact mainly in Addington, close to the city terminus of suburban passenger services.
The conclusion for this post is that a suburban passenger service to Rolleston should not be considered a greater priority than one going north to Rangiora, as there is limited potential for increased passenger numbers other than at Rolleston, and because most passengers would only be carried between the two terminii. The only real advantages the Rolleston route has is that it is double tracked almost all the way and has good historical locations for stations that remain largely unimpinged on.