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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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APPENDIX E—IN-VEHICLE EXPERIMENTAL PROTOCOL

  1. After the eye tests, have the participant sit at the table. Read the following (all text in italics is read aloud to participant):

    We will go to the Smart Road shortly. First I want to orient you to the study. For the first section, you will evaluate the glare for the different vision enhancement systems. Glare can be thought of as the amount of discomfort you experience from the oncoming lights of a vehicle. To do this, you will drive down the road and there will be a parked vehicle in the opposite lane from you with its lights on. Over two segments of road, I will ask you to evaluate the glare you experience during that segment of road. So, the road will look like this (show diagram). During that time, I want you to look straight ahead—never at the glare source—and rate the glare you experience with this scale (show scale). For this scale, you would give the glare a rating of 1 if you think it is unbearable. You would give a rating of 3 if you think the glare is disturbing. A rating of 5 would mean that you perceive the glare to be just acceptable. Seven would mean that you think the glare is satisfactory. And finally you would give a rating of nine if it is just noticeable. You can choose any number you want between 1 and 9 to rate the glare. So, I will have you drive and, while looking straight ahead, I will tell you “Begin” at the beginning of the road segment (point to on diagram). I want you to think about what rating you want to give the glare until I ask, “What is your rating?” At that time, I want you to tell me how you want to rate the glare according to the scale. For each parked vehicle we approach, we will do that twice—once at a far distance and once at a closer distance. Do you have any questions?

  2. Answer any questions.

    Take the participant to the rental vehicle. Orient them to the vehicle by showing them how to adjust their seat, lights, and the steering wheel.

    You will notice that your side and rearview mirrors have been covered. This is to reduce the glare that you might get from other vehicles.

    In addition, this is the windshield wiper. I am going to ask you not to use the wipers at all during the study. I am pointing them out to you so you can try to avoid accidentally starting them.

  3. The participants will drive to the road.

  4. Radio the onroad experimenters that you are ready to begin.

    First we will drive down the road to get you used to the road and the vehicle. Go ahead and drive down the road at a comfortable speed.

  5. Allow the participant to drive down the road at their speed. The second vehicle can begin once the first vehicle is out of sight. If you feel the speed is excessive, you can ask them to slow down. You may also need to ask them to slow down if they are getting close to the vehicle in front of them.

    First vehicle at the bottom of the hill:
    • Pull all the way to the first parking space.
    • Put the vehicle in park and have the participant take their foot off the brake.
    • Ask participant to close their eyes until the second vehicle is in place.
    • Review glare training.

    Second vehicle at the bottom of the hill:
    • Pull into the second parking space.
    • Put the vehicle in park.
    • Hold up poster board cut-out over passenger side window.
    • Review glare training.

    Now we will complete the glare portion.

    You will drive this vehicle up the road at 25 miles per hour. While you are driving, you need to look ahead and never directly at the oncoming lights. Along the way, parked vehicles will be facing you on the other side of the road. At two separate times, I will ask you to rate the glare for that vehicle. You will use a scale from 1 to 9. Again, the scale is as follows:

    1. 1: Unbearable
    2. 3: Disturbing
    3. 5: Just acceptable
    4. 7: Satisfactory
    5. 9: Just noticeable

  6. Show them the sheet with the red flashlight.

    When I need you to begin evaluating the glare, I will say, “Begin.” I then want you to think about the rating you want to give that headlight. I will then ask, “What is your rating?” At that time, I want you to tell me your rating for that entire stretch of road. We will repeat that for the light a second time over a different stretch of road for a total of two ratings per headlight. This will repeat until you see all of the headlights for this part of the study. And remember to always look straight ahead, never directly at the lights. Do you have any questions?

  7. If they have no questions, wait at the bottom of the hill until the onroad experimenters indicate they are ready to begin. At that time, indicate to the onroad experimenters that you are beginning to drive up the road. Vehicle 2 must wait until Vehicle 1 is out of sight before driving up the road.

  8. Have the participants drive at 25 miles per hour until you have asked them to rate the oncoming headlamps twice. You will know when to ask them to rate the glare when you pass the onroad cones. There are four cones on each side of the road. Using the ones on the right side of the road, have the participant start evaluating at the first cone (1300 feet from glare source) and give a rating at the second cone (1000 feet from glare source). Begin the second evaluation at the third cone (450 feet from glare source) and ask for a rating from the participant at the fourth cone (150 feet from glare source). Indicate the areas by saying “Begin” and “What is your rating?” Continue up the road to the second glare vehicle and repeat the procedure. Remind the participant before each rating to look straight ahead and never directly at the light.

    First vehicle at the top of the hill:
    • Pull up to white line just before the top of hill.
    • Wait for headlamp glow from 2nd vehicle to appear.
    • Pull up to the first cone on the left side of road.
    • Put vehicle in park.
    • Remind participants of scale and to not look directly at the lights.
    • Go down the road once the onroad experimenters indicate they are ready.

    Second vehicle at the top of the hill:
    • Pull up to first cone on the right side of the road.
    • Put vehicle in park.
    • Remind participants of scale and to not look directly at the lights.
    • Go down the hill when the first vehicle is out of sight.

  9. Repeat the evaluating/rating procedures for remaining VES.

  10. Repeat the evaluating/rating procedures on the way up the hill.

  11. When the participants return to the top of the hill after the final lap, they will park at the LAST cone they come to.

 

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