Graduation Year

2005

Document Type

Thesis

Degree

M.S.C.E.

Degree Granting Department

Civil Engineering

Major Professor

Dr. John Lu.

Co-Major Professor

Larry Hagen

Keywords

Crash rate, Crash data, Intersection approach, Operations, Crossroad

Abstract

Signalized Intersections on the State Roads in Hillsborough and Pinellas County, Florida with observed left turn lane overflow (spill) were selected for a safety and operational study. The study analyzed the crash data for safety hazards that the situation presents. Crashes within 100 feet from the center line of the crossroad of intersections under study to distances 200 feet beyond the end of the turn lane were chosen for the analysis. Left turn overflow is the situation at the approach of an intersection where left turning vehicles back up from the turn lane into the through traffic lane. Crashes within the intersection legs with the left turn lane overflow problems resulted in more crashes than the intersection legs without the spill problem at 95 percent confidence level. However the result was not overwhelming when 3 leg intersections are combined with 4 leg intersections.

The rush periods within the leg of the intersection where left turn overflow occurred did not seem to have any correlation at all using paired t test.

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