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Region, band, corridor, alignment in map study

Short answer

Route location narrows from region (whole area between terminals) to band (region excluding major barriers, several km wide) to corridor (narrower strip with probable alignments, hundreds of meters to km wide) to alignment (exact centerline fixed after surveys). Each step uses progressively detailed map study and field surveys to refine the route.

Define and describe the terms region, band, corridor and alignment with respect to the map study for highway route identification.

In route location the study narrows step by step from the largest area to the smallest.

  • Region: the whole area, usually a large one, between the two terminals and including all the controls, within which the route can be placed. It is identified from small-scale maps, e.g. the zone between Kathmandu and Pokhara.
  • Band: the part of the region left after the large barriers (high mountains, big lakes, reserved forests) are excluded. It contains the feasible routes and is found by studying maps and aerial photos. Its width is typically several kilometres.
  • Corridor: a narrower strip within the band that contains the probable alignments, found after more detailed map study and reconnaissance. Its width is a few hundred metres to a kilometre.
  • Alignment: the exact centre line of the road within the corridor, with all its curves and gradients, fixed after the preliminary and final location surveys.
 Region  >  Band  >  Corridor  >  Alignment
 (largest)                         (one line)

✓ Answer checked by Claude Opus 5.5 (high effort)

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