Not had many years walking and always used set walks (with distances) by other people instead of creating my own. Just wondered what the best way of measuring a walk on an OS map is and are there any other factors I should take into account for the walk's distance. For instance, I guess measuring from a map only gives a flat distance - how do I account for ascent and descent? Is there an overall grading / measurement scale for a walk?
Any thoughts on this would be gratefully received.
For measuring distances, purchase an opisometer (map measurer) available from most outdoor shops for about £10.
You also have to take into account the total amount of height gain (i,e. the total amount of walking uphill not the highest point reached). This can be done by counting the contours on rising ground. I'm told that mapping software will not give an accurate figure because contours are not counted but heights are averaged over an artificial grid.
In mountainous country, the generally accepted method of calculating the time required to complete a walk is by using Naismith’s Rule. The classic definition states: • allow one hour for every five kilometres measured on the map plus an additional half hour for every three hundred metres climbed This is more usefully defined now that all our maps are metric and the height gain between contours on both Landranger and Explorer maps in upland areas is 10 metres as • allow 12 minutes for every kilometre measured on the map plus an additional minute for every contour crossed N.B. the distance between contours on HARVEY maps is 15 metres so 1.5 minutes should be added to every contour crossed (it’s easier to calculate if you add 3 minutes for every two contours crossed).
Example: • total distance meaured on the map:10 km • total height climbed: 870 m Therefore • time required to walk 10 km (12 x 10) 120 mins • time required to climb 870 metres (870 ÷ 10) 87 mins • Total 207 mins Note that the average speed is 10 x 60 ÷ 207 = 2.9 kph but if the walk were level the average speed would be 10 x 60 ÷ 120 = 5 kph. Naismith’s rule assumes average fitness and good conditions, so extra time should be allowed for: • bad weather • difficulties in route-finding • heavy packs • uneven and boggy ground • river crossings Remember, too, that a party tends to be slower than a solo walker because time is wasted by • queuing for stiles • taking photographs • calls of nature If these factors have to be built in then it is usual to amend Naismith’s Rule by reducing the number of kilometres covered in an hour. Many walkers wearing only a light pack find that, even in good conditions, it is more realistic to allow one hour for every four kilometres (15 minutes per kilometre). Backpackers should consider basing their calculations on one hour for every 2.5 kilometres (approx. 25 minutes per kilometre). Once you have made your calculation you then have to add an allowance for meal breaks. Remember, that it is safer to over-estimate the time that a walk will take!
If you keep records of time taken for walks you will be able to modify Naismith's Rule to suit yourself.
Hugh, thanks very much for your reply. I've taken on longer (and steeper) walks recently and thought that height gained must be taken into account - I was moving upwards a lot, but not forwards very much!
I think that using the above information prior to a walk will also help me recognise its difficulty more easily.
Peter, as an alternative to buying a map measurer you can always use a piece of string. Or, as I do, estimate the distance using the kilometre grid squares - I count each one my route goes through as a km, and generally find it evens out. By eye I may make allowance for ones where the route is clearly much more or less than straight through the square, calling them 1/2 or 1&1/2. With a bit of practice I find that my quick estimate usually comes out at + or - a mile over anything up to around a 15 mile route (having counted the squares I multiply by 5 and divide by 8 to convert to miles). It's good and quick unless you really want to be more precise.
Apart from that though, Hugh's given you plenty to work with.
I am surprised at the above answers. Get a half decent mapping program and it will do the work for you and far more accuratly than the old wheels or bits of string.
Same as Matt, it's easy enough to roughly estimate distances using the kilometre grid squares but I multiply by 1.5 to convert to miles.
As for timings I've tried Naismith's Rule (5km per hour plus 30 mins for every 300m) ascent but find that just about any high level route works out at around 3km per hour overall so just use that as a guide. As Hugh says, with experience you'll be able work out your own average speed.
Cush - yes I do that when at home planning routes but it's not so easy when you're out there trying to work out long it's going to take you to get back to base!
Combination of the above - mapping software will nail the issue but frankly a finger and a map gives a ballpark distance and as in general I'm hillwalking the ascents are in big easy to identify chunks. I know about how fast we walk on roads, peat bogs ascents so plan that way.
only after you've worked out your own personal naismith cush and then keep adjusting it as you get better. i now find that just looking at the map on screen i get an answer pretty close to the naismith.
I am surprised at the above answers. Get a half decent mapping program and it will do the work for you and far more accuratly than the old wheels or bits of string.
Aye, and why do long division or multiplication when there are calculators? Perhaps because we can?!
Don't get me wrong, mapping software has it's place and can be great (I do use it), but:
- it costs (ok, so do maps)
- it does distances well (if you bother to plot every twist and turn), but can be way out with height gain and loss
- you don't always have access to it.
With a bit of practice the manual estimates can be done quickly and very accurately, and be more than adequate for most purposes.
My trips are fairly small these days (15-25 miles on foot, maybe 40 + on the bike) I allways work out a route on the computer before hand and set it down as a route card with a printed A4 map coverage usefull, saves time and a GPS helps to pin point my position at any time but when the batterys run low it can be a bit of a b****. So I always carry a full map and compass.
