Highway Rapid is situated 300m below Musson's Weir after some narrow channels of fast moving water and a large calm pool. The N3 bridge is your land mark.
You will enter Highway Rapid immediately after you pass under the bridge. It is not a very difficult rapid, but if you are on the wrong line, you can damage your boat.
The easiest line is centre-right which is wide and fairly straight forward. It is rocky so keep the boat straight in medium/low conditions. In high water some nice stoppers form here. The deepestpart of this channel is close to the little clump of grass on your left, in the centre of the rapid (see image below). The most important thing to remember is to avoid river left, in other words the outside of the bend.
There is also a line down the right which has the advantage of a more even gradient and therefore less of a drop. It is however a tight line and if you get it wrong it can lead to problems. It is difficult to get your bearings without scouting it carefully and easy to end up bashing rocks or getting stuck. Get it right and you will not touch a rock even in low-ish levels. In very full conditions you can keep extreme right all the way down with ease.