Straight Line Maps

Straight Line maps are a common navigational rallying instruction that frequently give beginner and clubman navigators a lot of trouble. They are often described as a picture of how the mapped route would look if it was a piece of string that was then pulled straight, with all of the connecting roads still attached. Are you confused yet?

1.06a Let me try another explanation. The drawing to the left is a straight line map. Your objective is to travel from E to F. Each place where the smaller lines connect to the main line is an intersection. Think in terms of instructions to "leave one / two road(s) on your left / right". If there are two connected lines, you will find a 4-way intersection. Otherwise, it must be a 3-way. A dotted line indicates a dead-end road or a trail.

Let's work through this example. The first three intersections are 4-ways. At the first, "leave a road on each side" - so you'd go straight ahead. At the second, "leave 2 roads on your left" - so you'd make a right turn. At the third, "leave 2 roads on your right" - this is a left turn. Those are the easy ones and you will know what to tell your driver to do before you find the intersection.

Now let's look at 3-way intersections. The 3 diagrams below illustrate the different types of 3-way intersections that you might encounter, assuming that you are entering the intersection from the dot at the bottom of each drawing.

Fig. 1 (1.06b)

Now let us consider the fourth instruction on our straight line map. "Leave 1 road on your left". If you find intersection A, you will go straight ahead, leaving the incoming road on your left. If you find an intersection like B, you will turn right, leaving the road on which you had been travelling on your left. If you find a "T" intersection such as C, you would turn right, leaving the other side of the "T" on your left. I'll leave you to work through these same options for the fifth instruction.

Instructions 6 & 7 take you over a railway crossing and then a bridge. Instruction 8 is to leave two successive roads on your left. This is not a 4-way intersection as these roads are not connected!

Tell your driver that you are in a straight line map section as soon as you start one, and then give them the instructions as noted above - "leave a road....". That way, both of you will understand the correct direction to take as soon as you come to the next intersection.

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Last Updated: 2001-04-18
Copyright © 2001 Gail L. Walker, reproduction forbidden without written authorization.