A couple of weeks ago I looked at the cost of the the Western Ring Route which when it is all said and done will have cost us over $3b however I did miss out some important details. I forgot about the impact on the connections to State Highway 1 in both the north and the south. Readers may recall than when the connection at Manukau was opened in 2010 there was chaos on the Southern motorway as scores of vehicles joined from SH20 which resulted in considerable congestion and frustrated motorists. As a quick fix the NZTA was forced to install ramp signals on the connection to the South to control the flow but said that the long term solution was to widen the motorway further between Manukau and Papakura to relieve the pressure. They also realised that the same thing might happen on the Northern motorway where SH18 joins SH1 so said they want to widen that part too. But how much will these works cost?
Another of the papers the NZTA released to me was their State Highway strategy from 2010 which sheds some light on the issue. In the South they are only showing the costs of adding a third lane southbound from Hill Rd to Takanini which would cost $40-$80m but they all four stages would likely need to be completed before ramp signalling could be removed from the SH20-SH1 connection. I think we could easily add in an extra couple of hundred million for the other works based on the costs we have seen elsewhere.
In the North it is going to cost even more, the paper says that the desire is to the route fully upgraded to expressway standard which means they would need to grade separate the likes of Paul Matthews Rd as well as installing ramps to allow motorway to motorway connections. Widening would also need to take place at least to Greville Rd which would also need an expensive upgrade.
All up from the listed projects we have additional costs in the range of $565m-$910m not including the projects out south that haven’t been costed. All of this is on top of the other $3 billion we would have already spent on the WRR which means that when all is said and done this one motorway would have cost more than $4b alone.