Public Works

Each intersection has the potential for several different types of vehicular conflicts.  The possibility of these conflicts actually occurring can be limited with proper sight distances and appropriate traffic controls.  Specified areas along intersection and access approach legs and across their included corners should be clear of obstructions that might block a driver's view of potentially conflicting vehicles.  These specified areas are known as clear sight triangles.  These are called sight triangles.  The dimensions of the legs of the sight triangles depend on the design speeds of the intersecting roadways and the type of traffic control used at the intersection. 

Section 9.5 of AASHTO's A Policy on Geometric Design of Highways and Streets provides guidelines on intersection sight distance.  It provides charts to determine the sight triangle dimensions for various types of intersection control using different maneuvers for each including left turn, right turn, and crossing.  It is important to understand the diagrams provided in that the distance provided in the table depicts the distance parallel to the major road, not the hypotenuse of the triangle. 

Related Links
AASHTO Design Standards
2011 Green Book

Contact Us

Office Location:
Public Works Department
City Services Center
500 15th Avenue SW
Cedar Rapids, IA 52404

Phone Number: (319) 286-5802
Fax Number: (319) 774-5653

Office Hours:  
Monday - Friday 
8:00 AM - 5:00 PM


After Hours:
If you need immediate assistance to report malfunctioning traffic signals, traffic sign repairs, or deficient construction traffic controls, please call the Police Department Dispatch at (319) 286-5491

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