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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-HRT-04-138
Date: December 2005

Enhanced Night Visibility Series, Volume VII: Phase II—Study 5: Evaluation of Discomfort Glare During Nighttime Driving in Clear Weather

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(Experimenter reads all text in italics aloud to participant.)

  1. Prior to the participants’ arrival, make sure that all the needed forms are available and label them with the subject number.

  2. Greet participant.

  3. Record the time that the participant arrived on the debriefing form.

  4. Show driver’s license. It must be a valid Class A driver’s license to proceed with the study. Out of State is fine.

    Before we begin, it is required for me to verify that you have a driver’s license. Would you please show me your license?

    This research is sponsored by the Federal Highway Administration. The purpose is to gather information that will be available to the public, including car manufacturers. The goal is to determine the best vision enhancement systems to help drivers see pavement markings at night. The lights also need to be safe and not cause any discomfort for other drivers on the road.

    The study will take place on the Smart Road testing facility. The road will be closed off to all traffic except for experimental vehicles. There will be at most four experimental vehicles on the road at one time including the vehicle you will be in.

    During the experiment, I will be in the vehicle with you at all times. I will be responsible for asking you questions during the drive, recording some data, and monitoring the equipment. In addition, I will be able to answer any questions you have during the drive.

    You will be exposed to 11 different vision enhancement systems. You will make one lap on the Smart Road for each vision enhancement system. Your job will be to evaluate glare. Do you have any questions at this time?

    Now I have some paperwork for you to fill out. This first form tells you about the study, what your job is, and any safety risks involved in the study. Please read through the document. If you have any questions, please feel free to ask. If not, please sign and date the paper on the last page.

    • Give the participant the form.
    • Answer questions.
    • Have participant sign and date both forms.
    • Give the participant a copy of the informed consent.

  5. Ask the participants if they are a university employee. If they are, just give them the W–9 form. If they are not, have them sign both the W–9 and the University Voucher. To complete the W–9, the participant must fill out the following in the box:

    • Name
    • Address
    • Tax ID number (social security number)
    • Sign and date at the bottom

    The second form is a University Voucher stating they are not being “permanently” employed by our project. Have them sign the back of the form.

  6. Vision tests.

    Follow me and I will go through the vision tests with you.

    The results for all three parts must be recorded on the vision test form.

    The first test is the Snellen eye chart test.
    • Take the participant over to the eye chart test area.
    • Line up their toes to the line on the floor (20 feet).
    • Participants can leave on their glasses if they wear them for driving.

      Procedure: Look at the wall and read aloud the smallest line you can comfortably read.
      • If the participant gets every letter on the first line they try correct have them try the next smaller line. Continue until they miss a letter. At that time, record the one that they were able to read in full (line above).
      • If they get the first line they attempt incorrect, have them read the previous line. Repeat as needed until they get one line completely correct. Record this acuity.
      • Participant must have 20/40 or better vision using both eyes to participate in the study.

    The next vision test is the contrast sensitivity test. Take the participant over to the eye chart test area.
    • Line up their toes to the line on the floor (10 feet).
    • Participants can leave on their glasses if they wear them for driving.

      Procedure: We are going to test how well you see bars at different levels of contrast. Your ability to see these bars relate to how well you see everyday objects. It is VERY IMPORTANT you do not squint or lean forward while you are taking the test.
      • Point out the sample patches at the bottom of the chart with the three possible responses (left, right, or straight).
      • Cover one eye with an occluder. (DO NOT let the participant use his/her hand to cover the eye since pressure on the eye may cause erroneous contrast sensitivity test results).
      • Instruct the participant to begin with Row A and look across from left to right. Ask the participant to identify the last patch in which lines can be seen and tell you which direction they tilt. If the response is incorrect, have the participant describe the preceding patch.
      • Use the table in the ENV binder to determine if subjects’ answers are correct.
      • Each vertical column of numbers on the second part of the vision test form corresponds to a horizontal row on the chart. Record the last patch the participant correctly identifies in each row by marking the corresponding dot on the form.
      • To form the participant’s contrast sensitivity curve, connect the points marked.
      • Cover the other eye and repeat all the steps above.

    The last vision test is the test for color blindness.

    • Take the participant back to his/her desk.
    • Place the book containing the plates on the testing apparatus.

    Please hold the red end of this handle to your nose and read the number on the following plates.
    • Record the participant’s answers on the vision test form.


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