What is a Tangent - it is defined as a line, curve, or surface that touches another curve or surface but does not cross or intersect it. In road racing, the line is your actual running path and the curve it touches(but doesn't cross) is the road barriers (curb, median, sidewalks).
The shortest distance between two points is a straight line.
At McInnish Park, the park roads where we run the races are winding. Our natural tendency is to follow the shape of the road, hugging the curb. The course however was measured with "No Restrictions". What this means is that you are allowed to run in any part of the road as long as you stay on the road. You can use both sides of the road. Of course, if there is a car approaching, let the car pass before moving lanes. If there are runners approaching, you also have to stay on your right to not bump into each other.
For the 5K, not using the tangents makes the running distance about 142 feet longer. That's about 15 seconds more for a 30-min 5K runner.
To run a tangent, look straight at the edge of a curb and run a straight path to that point as shown in the course maps below.
Below is the view on the first right turn. Follow a straight line instead of the fence.
Below is the runner's view of the above section. Use both lanes for the shortest route.