Cul-de-sac Lot Frontage Shortfall
A developer submits a 24-lot preliminary plat. The zoning ordinance requires a minimum lot width of 80 ft at the front setback line and a minimum frontage of 60 ft at the right-of-way. Lots 1–6 front on a 50-ft right-of-way cul-de-sac with a 50-ft radius bulb. Your layout puts the front setback line 25 ft from the right-of-way, which at the bulb falls on a chord. Lot 3 measures 58.2 ft of frontage along the ROW arc and 79.1 ft at the setback line. The ordinance also requires a minimum lot area of 9,000 sq ft; Lot 3 computes to 9,150 sq ft. The planning commission has asked for your certification that the plat meets the ordinance. A note on the plat says 'dimensions are approximate.'
1. Does Lot 3 comply, and what must you change before certifying?
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Frontage: 58.2 ft < 60 ft required - noncompliant. Setback width: 79.1 ft < 80 ft - noncompliant. Area: 9,150 sq ft ≥ 9,000 sq ft - compliant. Two of three tests fail, so Lot 3 does not meet the ordinance. You cannot certify compliance. Options: (1) widen the lot by shifting the side lines - but the adjacent lots then shrink and must be rechecked; (2) reduce the bulb radius or reposition the setback line (only if the ordinance defines front setback from the ROW line and allows a chord measurement - verify the exact ordinance language); (3) seek a variance. Also remove or correct the 'dimensions are approximate' note - a plat offered for approval must show accurate, computed dimensions and curve data (delta, radius, arc, chord, tangent). Recompute all six bulb lots, not just Lot 3, since any shift cascades.
2. How should frontage be measured on a curved ROW, and why does the method matter here?
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Frontage is measured along the right-of-way line - for a curved ROW, along the arc, not the chord. Measuring the chord understates frontage on a convex (bulb) frontage and overstates it on a concave one. Here the arc is 58.2 ft; the chord would be slightly shorter, so arc measurement is the more favorable reading and still fails. The setback width is measured along a line parallel to the front lot line at the required distance; on a curve that line is a concentric arc, and lot width at setback is the arc or chord depending on ordinance wording. State your method on the plat and in the certification so the reviewer can verify it. If the ordinance is silent, use the arc and note the assumption.