5.0 Design Criteria for Access Management
The design criteria outlined in this chapter are based primarily on the TAC Geometric Design Guide for Canadian Roads and include key principles such as roadway classification, entrance limits, access spacing, alignment, and other access-related factors critical to road safety and efficiency.
5.1 Roadway Classification
A functional roadway classification system establishes a hierarchy that defines the role and function of different types of roads, from Freeways to Public Lanes. The system helps minimize conflicts between traffic and land access, prioritizing movement efficiency and safety. The major classifications, and their characteristics, are as follows:
- Freeway/Expressway: High-volume, long-distance, high-speed movement; no direct access to abutting lands.
- Arterial: Moderate-to-high traffic volumes and speeds, limited land access; connects to freeways, arterials, or collectors.
- Collector: Moderate traffic volumes over shorter distances, intermediate access control.
- Local: Light traffic volumes with full property access, connecting to public lanes and collectors.
- Public Lane: Provides single-loaded access to individual properties.
Huron County focuses strictly on managing arterial roadways, ensuring proper connectivity with other road types.
5.2 Maximum Number of Entrances
To maintain the integrity of the road network, minimizing private site access to County roads is preferred. Access should be provided via local roads where possible. The number of entrances per property is controlled to avoid excess. For instance:
- Farm Entrances: One per farm, with allowances for additional field access where necessary.
- Residential: One entrance per property.
- Non-residential: A maximum of two entrances, spaced at least 30 meters apart.
For corner lots, access should be provided from the lower classified road.
5.3 Access Spacing and Corner Clearance
Access points should be spaced appropriately to ensure safe and efficient traffic flow. For example:
- Signalized Intersections: Minimum 400 meters for rural arterials and 215 meters for urban arterials.
- Major Access Connections: 300 meters for full movement on rural arterials, reduced for divided urban and urban arterials.
- Corner Clearance: A minimum clearance between intersections and driveways must be maintained, varying by road class.
5.4 Access Alignment
Driveways should align with opposing ones where traffic volumes are high. Offsets must be managed to prevent turning conflicts, with minimum offset distances set based on the type of intersection and whether left turns are allowed.
5.5 Intersection Angle
Driveways should intersect at near-right angles (90 degrees) to ensure good visibility and minimize collision risks. A minimum acute angle of 70 degrees is acceptable for two-way traffic. In industrial areas, one-way driveways may have angles between 45 and 60 degrees.
5.6 Shared Access
Joint or shared driveways between properties are encouraged to reduce the number of access points on County roads. In cases where this is not immediately feasible, provisions should be made for future shared access through legal agreements or future development plans.
5.7 Driveway Grades
Driveway grades must accommodate road classification, drainage, pedestrian movement, and safety for both vehicles and cyclists. Urban driveways should slope away from the roadway to control surface runoff, while rural driveways should align with shoulder crossfall for maintenance.
5.8 Sight Distance
Adequate sight distance is crucial for safe entry and exit from driveways, especially along arterial roads. The sight distance needed depends on the design speed of the road and is based on stopping, crossing, and turning sight distance requirements.
5.9 Access Width and Radii
The width and corner radii of driveways depend on the volume and type of vehicles served. Driveways should balance being wide enough for safe operation but narrow enough to discourage erratic maneuvers. Minimum and maximum widths vary by land use and traffic volume.
5.10 Clear Throat Length
Clear throat length allows vehicles to queue on the driveway without blocking internal circulation or spilling onto the road. This is especially important for high-traffic developments like drive-throughs and major commercial sites.
By adhering to these criteria, Huron County ensures that its roadways operate efficiently, balancing traffic movement with access needs.
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