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When Optimal Routes Still Feel Wrong: Introducing Job Proximity Scoring

Mathematically optimal routes can still frustrate drivers. Your route optimizer minimizes total travel time, but your courier gets sent back to the same street three times in one shift. The system says it's efficient. Your driver disagrees.

By
Bert Van Wassenhove
on
19/01/2026

This disconnect between algorithmic optimization and practical routing surfaces regularly in last-mile delivery. Even when travel time is minimized, routes that revisit the same geographic area multiple times create unnecessary complexity. Drivers make wrong turns returning to neighborhoods they just left. GPS systems recalculate repeatedly. What looks efficient on paper feels wasteful on the ground.

The Gap Between Mathematical and Practical Efficiency

Traditional route optimization algorithms focus on minimizing total distance or time. They're good at this—VRP solvers have decades of research behind them. But they treat every job as an independent point in space, optimizing the sequence without considering geographic clustering.

The result: a route might send a technician to job A in neighborhood 1, then to job B in neighborhood 2, then back to job C in neighborhood 1—because that sequence minimizes the total route time by 3 minutes compared to completing A and C consecutively.

Most routing systems address this through rigid pre-grouping. Planners manually cluster jobs into geographic zones before optimization begins, or the system automatically merges nearby jobs into compound stops. Both approaches sacrifice flexibility. Pre-grouped jobs can't be reassigned across zones when time windows conflict or vehicle capacity is exceeded. Merged stops become inflexible units that prevent granular optimization.

A Different Approach: Proximity as a Soft Constraint

Solvice's Job Proximity Scoring treats geographic clustering as an optimization signal rather than a hard boundary. Instead of forcing jobs into predefined groups, the feature encourages the optimizer to complete nearby jobs consecutively—while still allowing the algorithm to break this preference when other constraints demand it.

The mechanic is straightforward: you define a proximity radius (between 50m and 1500m) around each job. When the optimizer considers completing two jobs back-to-back within this radius, it receives a positive score. When it routes a vehicle away from a cluster before completing all nearby jobs, it incurs a penalty.

The strength of this preference is controlled by a weight parameter. Set it too low, and the optimizer ignores proximity entirely. Set it too high, and you recreate the rigidity of pre-grouped zones. The optimal setting depends on your specific operation—high-density urban delivery needs tighter clustering than rural service routes.

How Job Proximity Scoring Works

The feature operates during route optimization, not as a preprocessing step. As the metaheuristic explores different route sequences, proximity scoring influences which solutions score higher in the objective function.

When evaluating a route sequence, the optimizer calculates:

  1. Cluster identification: For each job, identify all jobs within the defined proximity radius
  2. Sequence scoring: When consecutive jobs in a route are within proximity range, apply a positive weight
  3. Penalty assessment: When the route exits a geographic cluster before completing all jobs in that radius, apply a negative penalty
  4. Balance calculation: Weight the proximity score against other objectives (travel time, time windows, capacity constraints)

The algorithm continues to optimize across all constraints simultaneously. A route might still split a cluster if doing so prevents a time window violation or balances vehicle capacities more effectively. Proximity is a preference, not a requirement.

Implementation Parameters

Job Proximity Scoring requires two configuration values:

Proximity Radius (50m - 1500m): Defines the geographic range for clustering jobs. Common settings:

  • Urban apartment buildings: 50-100m
  • Residential neighborhoods: 200-300m
  • Business parks or campuses: 500-1000m
  • Rural service areas: 1000-1500m

Proximity Weight: Controls how strongly the optimizer should favor geographic clustering relative to other objectives. Start with moderate values and adjust based on route acceptance rates and driver feedback.

The feature works with all standard VRP constraints. Jobs with time windows, capacity requirements, or skill matching still respect those constraints—proximity scoring simply adds another factor to the optimization objective.

Practical Use Cases

Dense Urban Delivery

An e-commerce delivery service operates in a downtown area with 200+ delivery points per day clustered in commercial districts. The optimizer tends to fragment routes across neighborhoods when optimizing purely for time.

Setting a 200m proximity radius encourages street-by-street completion. The courier clears an entire block before moving to the next street, reducing navigation errors and missed addresses. The GPS system stops recalculating as frequently because the courier isn't zigzagging across the service area.

Field Service in Business Parks

A maintenance contractor services office buildings across several business parks. Each park contains 5-15 buildings spread across 500-800m. Without proximity clustering, technicians might visit Park A in the morning, drive to Park B, then return to Park A in the afternoon—because the afternoon job has a 2-4 PM time window and the algorithm optimized around that constraint.

A 600m proximity radius with moderate weighting helps the optimizer recognize when it's worth extending a morning time window slightly to keep all Park A jobs in one visit. The technician completes the park in one trip rather than returning later, reducing total vehicle miles even if it means arriving at one job 15 minutes earlier than optimal.

When to Use Job Proximity Scoring

This feature targets operations where:

  • Jobs cluster geographically, but aren't always in the exact same location (unlike merged multi-stop deliveries)
  • Drivers need flexibility to handle time windows, priority changes, or last-minute additions
  • Navigation complexity creates friction beyond what travel time captures
  • Geographic context matters to customer experience (e.g., servicing all apartments in a building on the same visit)

It's less useful for:

  • Highly dispersed service areas where jobs are rarely within proximity range anyway
  • Operations with rigid pre-planned territories that already enforce geographic boundaries

Balancing Optimization Objectives

Job Proximity Scoring adds another dimension to the multi-objective optimization problem that VRP solvers already manage. The algorithm balances:

  • Total travel distance/time
  • Time window compliance
  • Vehicle capacity constraints
  • Driver skills and qualifications
  • Geographic clustering (proximity)

You control the relative importance through weight parameters. In practice, start with moderate proximity weights and monitor:

  1. Driver feedback: Are routes easier to follow? Fewer missed turns?
  2. Completion rates: Are time windows still being met reliably?
  3. Total route time: What's the trade-off in additional travel time?

The optimal balance depends on your operation's priorities. High-density operations with tight time windows might use lighter proximity weights. Lower-density service routes with flexible scheduling might weigh proximity more heavily.

Implementation Considerations

Job Proximity Scoring is configured per optimization request through the Solvice API. No preprocessing or manual grouping is required—you specify the radius and weight, and the optimizer handles the rest.

The feature works with:

  • Warm-start optimization (preserving in-progress clusters)
  • Real-time job insertion (adding jobs to existing clusters)
  • Multi-day scheduling (maintaining cluster integrity across days)
  • Heterogeneous fleet optimization (different vehicles still respect proximity)

For dynamic scheduling operations, proximity scoring helps maintain route stability. When new jobs arrive mid-route, the optimizer can insert them into existing geographic clusters rather than creating new ones, reducing driver confusion about route changes.

Read the full documentation about Job Proximity Scoring here.

Moving Beyond Pure Mathematical Optimization

Route optimization algorithms excel at solving complex mathematical problems. But the quality of a route isn't determined solely by minimizing an objective function—it's also defined by driver acceptance, operational efficiency, and customer experience.

Job Proximity Scoring bridges the gap between computational efficiency and practical routing. By treating geographic clustering as an optimization signal rather than a rigid constraint, it helps create routes that feel intuitive to drivers while maintaining the flexibility needed for complex scheduling operations.

The feature is available now in the Solvice OnRoute VRP API. Start with a moderate proximity radius (200-400m for urban routes, 600-1000m for suburban/rural), set a reasonable weight, and adjust based on actual route performance.

For implementation details and API documentation, see the Job Proximity Scoring guide in the Solvice documentation.

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