Traffic and Safety Informational Series FAQs


The goal of this project was to make available clear, concise, and consistent answers to 25 common traffic and safety questions. The information may be altered, distributed, and used as seen fit by area officials and/or transportation professionals.


Any references to the MUTCD are to the 2009 edition.

The opinions, findings, and conclusions expressed in this publication are not necessarily those of the Center for Transportation Research and Education or the Iowa Department of Transportation.

Document Format

All documents are in PDF format.

If you have any questions or comments, please call CTRE at 515-294-8103.

Traffic and Safety FAQ Sheets

Download and/or save the FAQ documents individually below, or save the entirety of the FAQs, including the summaries, here.

Individual QuestionsTwo-Page AnswersOne-Page Summaries
1. Won’t a “Children at Play” Sign Help Protect Our Children?answersummary
2. How Many Bullet Holes Does It Take to Kill a Sign? (Sign Vandalism)answersummary
3. Won’t a Lower Speed Limit Lower Travel Speeds and the Number of Accidents?answersummary
4. Why Can't I Have Several Driveways to My Property Wherever I Want Them?answersummary
5. Why Aren’t There Better and Longer Lasting Stripes on the Road?answersummary
6. Why Can’t I Place a Business-Related Directional Sign within the Roadway Right-of-Way?answersummary
7. What Factors Are Considered when Locating, Controlling, and/or Marking Pedestrian Crossings?answersummary
8. Why Isn’t There a “School Bus Stop Ahead” Sign Everywhere a Bus Stops?answersummary
9. Why Can’t Speed Bumps Be Used on All Streets to Slow Traffic?answersummary
10. How Are Posted Speed Limits and the Locations of Speed Limit Signs Determined?answersummary
11. Could Traffic Signals Be Timed So I Receive a Green Light at Every Intersection?answersummary
12. How Are Pedestrian Signals Timed to Accommodate Pedestrians?answersummary
13. Why Can't Stop Signs Be Placed at Intersections to Reduce Speeding along My Street?answersummary
14. Why Can’t a Multiway Stop Sign Be Placed to Reduce Accidents at an Intersection?answersummary
15. What Is the Harm in Installing an Unwarranted Traffic Control Device?answersummary
16. Wouldn’t Installing a Traffic Signal Reduce the Number of Crashes at an Intersection?answersummary
17. What Are the Recommended Safe Driving Practices at Railroad Crossings?answersummary
18. How Are the Locations of Traffic Signs Decided?answersummary
19. How Does a County Make Decisions about Dust Control on Gravel Roadways?answersummary
20. When Are Stop Signs and Traffic Signals Appropriate for Intersections?answersummary
21. How Can Converting a Four-Lane Street to a Three-Lane Street Improve Safety without Increasing Congestion?answersummary
22. How Are the Locations of Light Poles Decided?answersummary
23. How Does a County Make Decisions about Paving Gravel Roadways?answersummary
24. Why Aren’t Crossing Guards Present at All School Crossings?answersummary
25. Won’t a Flashing Yellow Light Draw More Attention to a Sign?answersummary