Outside of cities, stay out of the highway Right-of-Way, or lateral boundaries. It is unusual that you will get permission to run parallel to a road when the route is inside the boundaries and that any crossings you must do will be by special permission and they usually must be made between 45 and 90 degrees. Routing inside highway limits is VERY dangerous for a number of reasons,
1.) Frequent work on the roads edges, maybe by people that can't read warning signs.
2.) Pipeline warning signs get knocked down
3.) In Colombia the risk of landslides near roads is higher than in other places because they have already filled the area with substandard compacted fill.
4.) In Colombia the sides of roads often handle drainage and rainwater runoff increasing risk of washouts on your pipe.
5.) In Colombia there is insufficient control of overweighted trucks
6.) Drainage ditches are often added to the sides of roads that don't have drainage now, or the drainage becomes insufficient in the near future.
7.) Drainage on the sides of roads is often poor, because the road has already caused disruptions to the natural drainage patterns.
Inside cities often the only place you can go is in the road. If that's the case, go for the center of the road.
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"The problem isn't working out the equation,
its finding the answer to the real question." BigInch
