1. Grand Ave & Duff Ave Craig & James CE 550 4/18/2007

2. Problem Statement Grand Ave/Duff Ave intersection is on the northeast part of Ames, with 36,600 vehicles entering the intersection each day. Figure 1 Grand Ave/Duff Ave Interesection

3. Problem Statement (Cont’) There were 33 crashes in this intersection during 2001~2005 period. Figure2 shows the summary of these crashes. The average property damage is $4,214. Figure 2

4. Figure 3 Problem Statement (Cont’) ‘Ran Traffic Signal’ and ‘Making Left Turn’ are the two major causes, which take about 79% of the total crashes.

5. Problem Statement (Cont’) It is surprised to discover that ALL the crashes by last 5 years are related to alcohol. Figure 4

7. ’Making Left Turn’ Crashes As there is no left-turn protected traffic lights in this intersection, usually the left- turn vehicles on the Grand Ave will pull upward a little bit to make an easy left-turn. This is the typical situation when a crash will happen.

11. One Crash in June 2002

12. Possible Solutions Majority – Left-turn incidents Garber & Hoel  Create one-way street  Widen road  Provide left-turn signal phase  Prohibit left turns  Reroute left-turn traffic  Channelize intersection  Revise Signal Sequence

13. Possible Solutions Traffic Signals  Retime Signals Increase amber phase Longer all-red phase  Advanced Warning

14. Recommended Solution Left-turn Incidents Grand Ave  Majority of Incidents  Protected left-turn only Duff Ave  Turning bays for left-turn  Protected left-turn only

15. Recommended Solutions Traffic signals  Retime signals Collect data on signal sequence

16. References Crash Mapping Analysis Tool, Version 3.6.0. Developed by Center for Transportation Research and Education at Iowa State University. PI: Dr. Reg Souleyrette. Lead Software Developer: Nick Burdine. Copyright 2002-2005. Crash Report Diagrams and Narratives. Prepared for use by the Iowa Department of Transportation, Office of Traffic Safety. Iowa’s GIS-SAVER:E5. Iowa Department of Transportation, Office of Traffic Safety. Dr. Michael D. Pawlovich. Garber and Hoel. Traffic and Highway Engineering, 3rd edition. 2002.

17. Questions ?? Thank you. ☺