In a highway alignment project, GIS is most effectively used to
- APerform least-cost path analysis by overlaying land use, slope, geology and environmental constraintsCorrect
- BDesign the exact superelevation of curves
- CCalculate the bearing capacity of the subgrade soil
- DDetermine the daily traffic volume from sensors
Solution
Concept
Least-cost path analysis and spatial multi-criteria evaluation in highway alignment
Formula
Total Cost = Sum(Distance × ResistanceWeight)
Step-by-step solution
1. Selecting a highway corridor requires balancing topographic, economic, environmental, and social constraints. 2. GIS facilitates overlaying weighted thematic raster maps (slope, land acquisition costs, soil stability, flood risk). 3. The least-cost path algorithm computes the optimal cumulative resistance trajectory across these layers. Answer: A
Explanation
In highway planning and route alignment, GIS excels at macro-level spatial multi-criteria analysis and least-cost path modeling. By integrating spatial layers of terrain slope, land use, geological stability, rivers, and environmental conservation zones, GIS determines the route corridor with minimum construction cost and environmental impact. Hence, option A is correct.
Why the other options are wrong
B) Superelevation design is performed using geometric design formulas and CAD software. C) Soil bearing capacity is determined through geotechnical laboratory testing and Terzaghi formulas. D) Traffic volume is monitored by pneumatic or inductive sensors, while GIS only displays or networks the counts.
Shortcut
Highway + GIS = Least-cost path overlay analysis; Superelevation & subgrade = Detailed civil/structural engineering.
Common mistake
Assuming GIS handles micro-scale structural calculations like bearing capacity or detailed curve superelevation drafting.
Correct answer: A) Perform least-cost path analysis by overlaying land use, slope, geology and environmental constraints