Roadway Standards Section 245 - Roadside & Clear Zone

245.1 General

Roadside and clear zone standards strive to ensure that the roadside remains free of fixed objects and is sufficiently flat in the event that a vehicle runs off the roadway, enabling the vehicle to recover under ideal conditions. For additional information, refer to the AASHTO Roadside Design Guide.

245.2 Clear Zone Measurement

The clear zone width is measured from the edge of the travel lane of the roadway, the fog line or bike lane line.
 

245.3 Clear Zone Standards

Minimum clear zone widths are defined by Table 2-11 and are enforced by Section 7.03.090(C) of the County Code.

245.4 Clear Zone Requirements

1. Fixed objects located along the edge of the traveled portion of the roadway should be located outside the clear zone. 
2. Fixed objects are defined by AASHTO's Roadside Design Guide and the County Code.

245.4.1 Fixed Objects Allowed in Clear Zone

The following permanent objects are permitted within the clear zone under the following conditions:

1. Approved street trees.
2. Mailboxes erected per the Standards for Installing Mailboxes on County Roads.
3. Fences and walls approved by Engineering or meeting the requirements of Section 130.2.
4. Illumination poles.
5. Approved street furniture.
6. Objects permitted by the County Code.
7. Other objects approved or installed by the County.

245.4.2 Embankments and Ditches

New construction of foreslopes and backslopes should be based upon Standard Drawings C110 to C140.  Proposed slopes within the clear zone should be "recoverable."  Slopes that are "critical" per the AASHTO Roadside Design Guide should be avoided with new construction.

245.4.3 Vegetation

Vegetation should not be allowed over a height of 30 inches in locations where it would limit sight distance per Section 240.  Overhanging tree limbs should have a minimum vertical clearance of 10 feet within the clear zone.  Overhanging tree limbs should have at least 14 feet of vertical clearance above the pavement surface over the traveled portion of the roadway.  Measurement shall be taken from pavement surface. 

245.4.4 Above Ground Appurtenances

Above ground appurtenances constructed as component parts of any underground utility line should be located outside the clear zone as practicable.

245.5 Clear Zone Exceptions

If fixed objects cannot be moved from the clear zone and cannot meet the standards of the County Code, Sections 245.1 through 245.4.3 and Table 2-11, the County may allow the obstructions to remain with consideration given to delineating or protecting the objects.

 

A part of the Roadway Standards.