Thursday, January 9, 2014

Features on a topo map - Data Date

Before planning your route, and certainly before trying to navigate your route, it is important to have an understanding of the features of a topo map. These maps are chalked full of detail and orienteering is one of the few opportunities to use every aspect of the map. If you aren't "seeing" the these features, you are making your navigation harder that it needs to be. The following few posts will be dedicated to specific aspects of topo maps that are important.

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Data Date

An important thing to know about maps, and Canadian topo maps specifically, is that they are not updated regularly. In fact, in many cases, they are woefully out of date. 

The date of the map will usually be found in the bottom left corner of the map.  A single map may also have data from several different years...or decades. If your map doesn't have a data date, ask the race director. 

From a practical standpoint, you can image how much an area can change over a long period of time. The things to keep in mind for old topo maps are: 
  • Major roads are more likely to still exist
  • Small roads and trails may or may not still exist
  • New roads and trails may have been created
  • Any man-made structure may or may not exist. This includes power lines, buildings, fences, etc. 
  • Natural features such as rivers, streams and elevations probably haven't changed
  • Beaver ponds may not exist or new ones may have appeared
Race directors take a special, sick, pleasure in using these "features" to cause havoc in your route. What looks like a very direct, easy trail between two CPs could actually be an overgrown swamp. Trust me, you do not want to carry your bike through an overgrown swamp. 

Forestry operations specifically will cause a great deal of differences between the topo you have and the reality in front of you. Large sections of trail may be gone or changed. 

In some cases, the race director will take pity on the racers and will draw in corrections on the map. The map on the right is an example of a section of map that was particularly out of date. We added in the blue trails to show where the real trails were located. Many (most) of the dotted trails were inaccurate on the topo. 

Generally speaking, if a race director has added a trail to a map, it is for a good reason. You should give it careful consideration.