We are considering updating our visibility triangle standards. Curious
what other Iowa zoning regs are out there on the issue. I notice that
several cities across the country make distinctions between alleys,
streets, driveways and also streets with sidewalks. The highest standards
seem to require a 45 foot triangle. Ours is 20 feet, which I think is a
little dated for modern traffic safety concerns. I've also seen cities
which used the functional class system to rule the triangle dimensions.

This is our current language:

(5) Visibility at Intersections.

(a) Definition. "Visibility Triangle" means the area created by the
intersection of property
lines at the corner of 2 abutting streets and a line connecting 2 points
on these property lines 20 feet from the point of
(b) Within the Visibility Triangle on any corner lot located in
Agricultural, Residential, or
Hospital/Medical districts, no fence, wall, or other structure shall be
erected and no foliage plant permitted to grow
to a height of more than 3 feet above the elevation of the established
street grade measured at the curb line at the
intersection of the streets abutting the corner lot.

Thanks in advance for your assistance!

Sam Perry, Planner
City of Ames, IA, Dept of Planning & Housing
Direct: (515) 239-5447
Front Desk: (515) 239-5400
Fax: (515) 239-5404
Email: sperry (AT) city (DOT) ames.ia.us
Web: www.cityofames.org

515 Clark Ave.
P.O. Box 811
Ames, IA 50010