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Cost Objective

Overview

The Cost Objective minimizes total operating cost by combining three cost components for each vehicle: a fixed activation cost, a distance‑based cost, and a time‑based cost. This objective lets you model real economic trade‑offs: some vehicles may be cheap to drive but slow, some fast but expensive, and some you'd rather not activate unless necessary because of high startup/usage overhead.

When to Use

  • Both driver labor time and distance‑driven expenses (fuel, wear, tolls) materially affect cost.
  • You want to discourage activating unnecessary vehicles by assigning a non‑zero fixed cost per vehicle.
  • Your fleet is heterogeneous (different cost rates per vehicle) and you need the optimizer to choose economically.
  • Neither a pure distance nor a pure duration objective captures your cost reality; you need a balanced trade‑off across time and distance.
  • You want to run "what‑if" cost sensitivity scenarios by adjusting cost weights.

Behavior

  • Each vehicle's total evaluated cost includes:\ Total Route Cost ≈ fixed + (distance_in_meters × per_km / 1000) + (time_in_seconds × per_hour / 3600).
  • All three fields are read from the vehicle's cost settings.
  • If per_hour is missing or falsy, a default of 3600 is applied.
  • If per_km is missing or falsy, a default of 1000 is applied.
  • If fixed is missing, treat it as 0 (no activation penalty) unless your application defines another default.
  • Costs are aggregated across the route; the optimizer selects assignments that yield the lowest total cost across all vehicles.

General Validation

  • All cost values (fixed, per_km, per_hour) must be ≥ 0.
  • Use consistent units: distances must match the scale implied by per_km (meters converted to km by dividing by 1000); times must match the scale implied by per_hour (seconds converted to hours by dividing by 3600).
  • Check scale balance: extremely large per_km versus tiny per_hour (or vice versa) can skew optimization; choose realistic ratios.
  • Provide fixed costs intentionally—set higher values to discourage opening extra vehicles; set 0 if activation cost is irrelevant.
  • Vehicle capacities, job amounts, and time windows must be valid; the solver enforces feasibility before cost comparison.
  • Ensure cost fields exist for every vehicle or confirm you are comfortable with the defaults that will be applied.