CE 552 HW 4: Speed study lab

A recent paper by Oliviera, et al, ( describes the use of radar to affect driver behavior (speeds) in the vicinity of work zones. Some 4 million of the nation’s estimated 20 million radar detectors are equipped to receive messages through radar that warn of hazards to traffic (Safety Warning System). So, highway and law enforcement agencies can deploy automated radars near workzones and other areas to warn drivers. Even if vehicle’s radar detectors cannot receive and display the warning message, the radar detector is still activated, and this is hoped to slow drivers or at least make them aware of potential danger. The paper goes on to say, however, that as few as 3% of vehicles passing a point may radar equipped[1]. They go on to say that even if all 3% reduce their speed, it has a negligible affect on the entire traffic stream.

Let’s depart from that comment. Let’s suppose that only 5% of vehicles are speeding “excessively”. If those vehicles using radar are considered to be the ones most likely to speed (not a bad assumption), then perhaps 60% of the speeders could be addressed by automated broadcast of radar.

The assumptions are shaky at best, but let’s proceed to ask the following questions …

  • How many and what types of vehicles use radar detectors?
  • How many vehicles speed?
  • How many of the speeding vehicles use radar detectors?

Design a safe experiment to collect some data to begin addressing these questions. We have borrowed a radar detector detector (not a typo) from the Iowa State Patrol for your use. Please be careful with the $1500 instrument on kind loan to us! The instrument detects the use of radar detectors – bet you didn’t even know that was possible! We also have, for you use, a state of the art radar gun.

We suggest you set up cones on the shoulder and wear safety vests for this data collection. You will need 12 volt power, and a good place to observe traffic. Find a safe place (you might try the State street overpass on US 30, or perhaps a county road overpass on I-35, a gravel road with not much traffic.) Have at least one spotter for safety, two machine operators and one data recorder in each group.

Collect 2 hours of data on speed, use of detector, and description of vehicle. If several vehicles approach at once, you may not be able to tell which one is using a detector. Also, once you trigger your radar gun, (or simply being seen) you may affect the speed of a vehicles. See if you can collect information on this behavior. Note any difficulties you have in collecting data and remember … safety first! Leave yourself an escape if a vehicle comes too close, and stay off the traveled way. If you have any doubts, err on the safe side. Be careful not to distract drivers or drop anything off the overpass.

Prepare a report that characterizes the procedure used, location and other information about the experiment, the raw data you collect, and statistical summaries as appropriate. Draw conclusions about the data, discussing the confidence you have in your results, any bias or suggested improvements in the procedure.

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[1] It is inconsistent to report that 20 million vehicles have radar detectors and say that only 3% are equipped … do the math!