Sugar Loaf

Cartographic confusion! Common map errors and how to avoid them

It’s often been said that, here in the UK, we’re lucky enough to have the best leisure maps in the world. Ordnance Survey mapping at 1:50,000 and 1:25,000 scales offer an incredible level of detail and accuracy while the increasingly popular Harveys maps offer a user-friendly alternative in some areas. Without the knowledge of how to interpret the map though, all that fine work is useless to the average walker, cyclist or trail runner.

Many of the symbols on the map are pretty self-explanatory and easy to understand (crosses for churches, green pictures of trees for forests and so on), but there are a few areas that can lead to confusion and bewilderment when out and about in the countryside. Here are a few of the common mistakes I come across when teaching navigation.

Scale

Many compasses have a handy ‘romer’ scale etched along the edges. This enables you to measure distances in increments of 50 or 100m at a glance. With romers available for maps at different scales however, it’s easy to mistakenly use the wrong one for the map you’re following! Romers on compasses are usually at 1:25,000, 1:50,000 and sometimes 1:40,000 scales. Using the wrong romer could lead to errors such as measuring a 1KM distance as being only 500m!

Where’s the path?

Do you know the difference between a track, a path and a footpath? Did you even know that such a difference existed? Ordnance Survey maps use coloured dashes to denote public rights of way, even where there may be no actual visible path in reality. Other symbols are used to indicate actual paths that should be found on the ground.

This often causes confusion amongst walkers trying to find a public footpath that doesn’t appear to exist!

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I like to explain this as green dashed lines (red on a 1:50,000) tell you that you have the right to walk on that particular route, but not necessarily the ability to do so. Black dashed lines tell you that you have the ability to walk there, but not necessarily the right! Where there is a green dashed line with black dashes beneath it, you have both the right to walk there and should probably expect to find a track on the ground.

Harveys maps are different again. These maps focus on physical features that can be found, so don’t necessarily indicate right of way information.

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The black dashes  on an OS map can be either a single line or 2 parallel lines. As a rough rule of thumb, I teach that the single line is a track that you should expect to be able to walk along whilst the double lines denote something that is probably broad enough to drive a land rover along.

Just don’t get the tracks confused with…

Boundaries

Physical boundaries are the easy (or easier anyway) ones to deal with. Those black solid lines criss-crossing the 1:25,000 scale maps represent walls, fences, hedgerows and, occasionally, lines of trees. Tougher to find can be the earthern embankments and trenches that can also be marked in the same way; one trick is to imagine what the map-maker could see from an aerial photograph. If they could see something about the height / depth of a wall, that’s how it will be marked.

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The really tricky boundaries marked on OS maps though are the ones that don’t exist! Civil parish boundaries, parliamentary constituency boundaries, county boundaries, national boundaries, national park boundaries, even European parliamentary boundaries (for now at least) are all marked on the map. Go to that spot though and you’re unlikely to find any evidence of them in reality.

Most of these administrative boundaries are marked as various schemes of dashes and dots, so it’s hardly surprising that I often see people mistaking them for footpaths and tracks. The only way to be certain of avoiding this issue is by learning the symbols thoroughly or, if in doubt, consulting the map key!

Back on Track

Once you recognise the common pitfalls in map interpretation the process of navigation begins to become clearer and a little easier. Armed with the knowledge of how to interpret the map accurately there should be nothing to stop you from making the most of it: get out and explore!

If you fancy developing your navigation skills with some hands-on training, find out more about our courses here.

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