Principle and complexities of route location

Basic principle of route location

The aim is to find the route which gives the minimum total cost to the nation - the sum of construction cost, maintenance cost, vehicle operating cost (including time cost) and accident cost over the life of the road - while serving the traffic and meeting the safety and environmental requirements. In short, the route should be short, easy, safe and economical, passing through the obligatory points and avoiding the points to be avoided.

The route is located in a systematic sequence: region -> band -> corridor -> alignment, using map study, reconnaissance, preliminary and detailed surveys.

Complexities of route location

1. Many conflicting objectives: the shortest route may be steep or costly; the cheapest may be long or unsafe, so a compromise is needed.
2. Large number of variables: terrain, geology, hydrology, land use, traffic, environment all affect the choice.
3. Uncertain and incomplete data: maps may be old and field data limited; future traffic is only a forecast.
4. Obligatory points may be far from each other or impose very difficult geometry (e.g. a pass).
5. Cost and benefit that cannot be easily valued: environmental harm, social impact, resettlement, loss of heritage.
6. Land acquisition and public opposition, political pressure and administrative boundaries.
7. Environmental restrictions (national parks, forests, wetlands, EIA).
8. Hydrological and geological risks in Nepal: floods, landslides, young unstable hills.
9. Interaction with other infrastructure (canals, power lines, existing roads).
10. Time and funding limits and need for staged construction.

Therefore, the location team should compare alternatives using a multi-criteria or economic analysis, and select the route that gives the best overall result.