Road Gradient info - where can I get it?

Is there a web site that shows maximum road gradients for major roads over ranges?

Now that we carry and tow much heavier weights, I need to consider this in our travel planning.

We recently did Cunningham's Gap, fully loaded and towing the Kedron. We pulled up the hill (very long as those who have done it will know) well, but in 2nd gear most of the way.

We are soon heading from Gold Coast to NT again and one of the routes we have previously used is via Toowoomba. I'm thinking the climb at the top of the range into Toowoomba is much steeper than anything at Cunningham's Gap, but that is a perception from memory only - I don't have the data. My first thought is to avoid the Toowoomba range climb and head North up the Bruce highway, before heading West (lots of options), but all are longer and they all cross the range at some point.

It got me thinking though, that it would be handy to have access to this sort of data when planning. Truckies must have access to it, or do they just learn by collective mistakes and experience?

From our experience with climbs that have the gradient marked, up to 12% is fine. Above that is worth avoiding if we can. We did a 14% climb recently and I needed 1st gear for the last 50 meters. If the climb was much longer or steeper, it might have been low range! A run up often helps, but that is not always practical due to windy roads, other traffic, other safety considerations and just not knowing what is ahead.

Norm C