Altitude profile?

G'day Kenham, if your total change in altitude is say 1,000 metres (1km) over your 150km journey then your average gradient for the whole trip would be 1 in 150 whereas if say the change in altitude from the bottom to the top of the hill is say 200m (0.2km) over a distance of say 4km then the grade specific to that section of road would be 1 in 20.
I've only made up these numbers as I'm not familiar with the area but hope this helps.
Regards, Gary M.

Thanks Gary, I understand what you are saying but it's not really what's happening. When I ask for the gradient profile it gives the whole trip as a graph and indicates the precise point of the steepest section, both up and down, with the gradient as a percentage. A 30% gradient, I assume, would rise 3 metres for every 10 metres horizontally - very steep - but only at that specific point. Problem is, when I enter a start and end point covering just that particular hill, it gives a different % gradient to when I enter a longer trip including that hill. That sounds very clumsy but I don't know how else to explain it. For instance, if I enter Wollongong to Sydney, it shows the steepest bit as a certain percentage but if I enter just that steep bit, the percentage is different. Hope that makes sense.

Hi again Kenham, I've never used Treks so probably can't help further. If you had access to a topographical map of the area you could estimate a gradient using the contours and horizontal distance but that's about all I can offer.
All the best, Gary M.

HI Kenham, I've just been trying to catch up as we have been away and just noted your query. Having just had a quick chat with David about this, he confirms that the linear accuracy in the data is restricted by the number of points in the file. To get the most accurate result, use a short distance. Hope this helps.

Thanks Michelle,
Perhaps I don't understand what gradient percentage actually means. I'm trying to simply find out what is the actual steepest part of a route I am planning as I tow a rather heavy caravan.
I am in Sydney so perhaps I could give an example. I wish to choose between Mt Ousley and Bulli Pass when travelling north from Wollongong. The Mt Ousley route, which I know and use often, has not just one climb but 3 or 4, meaning you go up a steep hill and down the other side 3 or 4 times but Bulli Pass has just one hill but it is, I think, a bit steeper. I want to find out, just how much steeper is it?
If I enter a route from south of Mt Ousley to a bit north of Mt Ousley, the gradient is shown as a certain percentage but if I enter a much longer route, say Nowra to Sutherland, The gradient at the same point on Mt Ousley is shown as a different percentage. That's what I don't understand. Surely a gradient is always the same percentage? It's always possible I am doing something wrong as well. Ken

Thanks Peter for your reply. I am still confused. I am after the steepest point and just how steep is it. I don't see how the distance of the route comes into it. Surely the steepest point is always in the same position and always the same grade regardless of how long the trip?