Permanent Corridor Dossier: Alton Darby & Western Boundary

Boundary transition analysis tracking Big Darby Accord conservation compliance, rural two-lane road stress, western annexations, and Darby Creek feeder watershed protections.

Status: Big Darby Accord Review & Annexation
Western Transition & Watershed Map
Accord Boundary
Annexation Infill
Substandard Culvert / Choke
DARBY ACCORD LINE ALTON DARBY RD SCIOTO DARBY RD ROBERTS RD EXT ANNEXATION TRANSITION INFILL No Turn Pocket (LOS E) Open Ditch Pinch-Point Clover Groff Run
Schematic overview of the Western Boundary transition zone and Darby drainage basin; not a boundary survey.
Corridor Ratings & Cross-Section Reality
Alton Darby @ Scioto Darby
LOS E
Peak AM left-turn delays
Alton Darby @ Roberts Rd
LOS D
Unsignalized gap delays
Roadway Cross-Section
Rural 2-Lane
No paved shoulders
Runoff Water Quality Rating
Tier 1 Target
Accord strict baseline
Jurisdictional Framework
Accord Governance: Big Darby Accord Joint Advisory
Township Jurisdiction: Norwich & Brown Townships
Max Density Target: 1 Unit / 2 to 5 Acres (Non-sewered)
Riparian Setback: 100–300 ft Buffer Mandate
Enforceable Big Darby Accord Commitments
  • Mandatory Conservation Open Space: All annexed transition PUDs must preserve a minimum of 50% contiguous open space dedicated to public conservation or passive recreation.
  • Non-Degradation Stormwater Standard: Strict requirement for on-site post-development infiltration mimicking pre-development hydrology to protect cold-water tributary fauna.
  • Central Sewer Tap-In Preconditions: No municipal water or sewer utility extensions granted west of the boundary without Big Darby Accord Advisory Panel review and approval.
  • Western Right-of-Way Dedication: Developers must dedicate 40 feet from the road centerline for future modern two-lane upgrade with grass swales instead of hard curbs.
Critical Boundary & Infrastructure Choke Points
  • Narrow Rural Shoulders & Deep Ditches: Alton Darby Creek Road lacks paved shoulders or recovery zones; sharp open ditches create severe safety hazards during commuter rush hours.
  • Bridge & Culvert Load Limits: Aging culverts crossing Clover Groff and Mud Run tributaries are not engineered for modern construction hauling or school bus volumes.
  • Annexation Boundary Disconnect: Rapid city annexations create an irregular "checkerboard" border between Hilliard, Norwich Township, and Brown Township road maintenance crews.
  • Scioto Darby Single-Lane Backups: Commuters heading east encounter single-lane congestion stretching past Leppert Road due to missing western roundabout or signal upgrades.
Data Source: Big Darby Accord Watershed Master Plan, Franklin County Engineer Roadway Inventories, and Ohio EPA Division of Surface Water.

Alton Darby & Western Boundary Transition