Waterside P2-CS030722�)
T H E C I T Y O F
COPPELL
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A X A S 1 8 9
MEMORANDUM
FROM THE
DEPARTMENT OF ENGINEERING
To: Ken Griffin, Director of Engineering/Public Works
From: Teresa Turner, E.I.T., Graduate Engineer _P1 1
Date: July 22, 2003
RE: 4 -Way Stop Study— Waterside Estates No. 2
Greenway Drive (major street) at Westlake Drive (minor street)
This is a follow -up to the traffic study completed on May 13, 2003. Dan Gray, who lives at 359
Westlake Drive, has further expressed concerns about visibility and stopping sight distance for
northbound drivers on Westlake Drive and eastbound drivers on Greenway Drive. He feels that a
4 -Way Stop situation at this intersection could be justified based on factors other than traffic
volumes and crash experience.
Staff conducted three studies to measure the sight distance in the direction in question. The results
are as follows:
Situation 1 —
Height of Drivers Line of Sight — 5 feet
Object Height — 4 feet
Sight Distance from Driver to top of Object — 950' feet
Situation 2 —
Height of Drivers Line of Sight — 5 feet
Object Height — 4 feet
Sight Distance from Driver to bottom of Object — 226 feet
"CITY OF COPPELL ENGINEERING - EXCELLENCE BY DESIGN"
Situation 3 (AASHTO) —
Height of Drivers Line of Sight — 3.5 feet
Object Height — 6 inches
Sight Distance from Driver to top of Object — 180 feet
COMMENTS
The minimum stopping sight distance set forth by AASHTO and the City of Coppell's Subdivision
Ordinance for a 30 mph street is 200 feet. Using the AASHTO guidelines, this intersection could
be considered questionable. There is a small dip on Greenway Drive approximately 180 feet west
of the intersection of Westlake Drive in which a 6 inch tall object could be momentarily lost by a
driver with an eye level at 3.5 feet. However, at a distance of greater than 180 feet west of the
intersection, sight distance is restored to Greenway's intersection with Samuel Blvd.
Attachments
"CITY OF COPPELL ENGINEERING - EXCELLENCE BY DESIGN"
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