Busy roads, rail lines and substations: assessing external factors
Mass appraisal often misses what is next door. It is a documentable argument.
A model working from size, age and class does not know your house backs onto a rail line.
The factors that matter
Arterial road frontage, a rail corridor, a substation or transmission line, commercial or industrial adjacency, a landfill or treatment works, floodplain, and airport noise contours. Each measurably affects sale price and is often absent from the assessment.
How to prove it
- Sales evidence: comparable properties on the affected side against those away from it. This is the strongest form — it shows the market pricing the factor.
- Official mapping: floodplain maps, noise contours, zoning maps.
- Photographs establishing the proximity.
What the assessor may already have
Many systems support an "influence factor" — an adjustment for exactly this. Ask whether one is applied to your parcel and to neighbouring parcels. Discovering that neighbours received one and you did not is a clean uniformity argument.
Be realistic
These arguments produce moderate adjustments, not dramatic ones, and they work best combined with a uniformity comparison against unaffected comparables.