By early next year Auckland’s train system should be running trains at 10 minute frequencies on the three main lines, plus the two trains per hour from Onehunga. That mean that basically we will have four lines feeding into Britomart – three with six trains per hour (tph) and one with two trains per hour (tph). This means frequencies along the various section of line within the isthmus area will be like this:I’ve yet to have this completely confirmed, but my understanding is that Britomart station cannot handle too many more than 20 trains per hour into and, because it’s a dead-end, out of the station.
Remember that this is before rail electrification even happens. Electrification will allow the trains to travel faster, quieter and much more efficiently but it won’t mean that any more trains than this can be operated on the system. We’ll also be able to make the trains longer over time, so the passenger capacity of the system certainly can be increased, but we won’t be able to increase the train capacity of the system until we get around to building the CBD rail tunnel. This means it will be very difficult to run trains to Hamilton, because there won’t be room at Britomart. This means we won’t be able to run trains at higher frequencies than one every 10 minutes, unless we start running trains directly between the western and southern lines (and therefore bypassing Britomart, the most popular station). This means it will be difficult to increase the number of trains from Onehunga to more than one every 30 minutes.
This is why getting on with planning, funding and building the CBD rail tunnel is a priority. We simply can’t do much to further improve the rail system until we complete that project. Throw in that tunnel and things change dramatically, in terms of the maximum capacity of the system (assuming that you probably wouldn’t run your trains at frequencies higher than one every 5 minutes): To explain a bit of potential for confusion, the area between Penrose and Newmarket is shown as 24 trains per hour in the direction towards the city: that would one train every two and a half minutes. Within the CBD rail tunnel I show 48 trains per hour because 24 could enter the CBD from the southern entrance (12 from the west and 12 from Onehunga/Airport) and 24 from the northern entrance (12 from the eastern line and 12 from the southern line via Newmarket and Parnell).
As you can see, the tunnel makes a pretty big difference.