Iron Gate stream, there are now 3 bridges here, and a safe parking place while driving north.
The original SH1 bridge in inland, and no there's no traffic, it has a cache. There is a safe pathway from the carpark, along the fence, through a wee gate, and down a path into the stream.
No need to cross the road or railway line, head under the bridges.
This is a great place to stop and see the scale of some of the road rebuild