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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-04-137
Date: December 2005

Enhanced Night Visibility Series, Volume VI: Phase II—Study 4: Visual Performance During Nighttime Driving in Fog

PDF Version (1.27 MB)

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Protocol for ENV-Objects

Front Seat Experimenters—Training

  1. Prior to the participant’s arrival, make sure that all the needed forms are available.

  2. Set up the conference room.
    • Close all the shades.
    • Turn on all overhead lights.
    • Turn off halogen lamps.
    • Position work light for vision contrast by placing it within the tape on the floor. Get color vision test, eye occluder, alcohol, and cotton balls.

  3. Greet participant.

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

  5. Ask to see driver’s license.
    • Must be a valid Class A driver’s license to proceed with the study. Out of state is fine.

    Experimenter reads all text in italics aloud to each participant.

    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 objects and pavement markings at night.

    This study will involve you driving different vehicles on the Smart Road, after you have completed a training session. We will pay you 20 dollars per hour at the end of the evening.

    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 two experimental vehicles on the road at one time including the vehicle you will be in.

    During the study, two experimenters will be in the vehicle with you at all times. The front seat experimenter will be responsible for asking you questions during the drive, recording some data, and monitoring the equipment. In addition, he or she will be able to answer any questions you have. You will be exposed to six different vision enhancement systems. You will make one lap on the Smart Road for each vision enhancement system. On these laps you will be exposed to several objects. Your job will be to tell me when you are able to detect the object, and when you are able to recognize what the object is.

    Do you have any questions at this time?
    (Answer questions if needed).

  6. Informed consent.
    • Give the participant the form-encourage them to read it.
    • Answer questions.
    • Have participant sign and date both forms.
    • Give the participant a copy of the informed consent.

  7. Tax Forms.
    • 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 other side of the form is a University Voucher stating they are not being “permanently” employed by our project. Have them print their name on the top of the form.

  8. 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 relates 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 participants answers on the Vision Tests Form.

  9. ENV Training.

    After the eye tests, have the participant sit at the table. Explain the following:

    The following presentation will provide instructions, definitions, and examples of the objects we will be using. You can ask me questions at any time. There will be some pages I will place extra emphasis on. Any questions before we begin the presentation?

    Answer questions as needed. Once there are no more questions, begin the instructions. Stress the following points:

    • Definition of detection versus recognition.
    • Stress safety (i.e. 10 mph, drive safely, etc).
    • Again, answer questions.

    Slide 1: This study is called Enhanced Night Visibility given that its purpose is to evaluate Vision Enhancement Systems. Tonight I will be one of the experimenters that will be riding with you.

    Slide 2: This is a timeline of how the night will break down. We are in the Laboratory Training portion right now. Once we are done with the lab training we will familiarize you with the Thermal Imaging System and the procedure for the experiment.

    Slide 3: The enhanced night visibility project is an extensive research project to determine what vision enhancement system configuration will best help people see objects on the road at night.

    We needed people to give us information on visibility and preference of the different vision enhancement systems. That is why you were asked to come here tonight. The information you give us will be compiled with other people’s data so we can determine the best configuration.

    We will be using four different vehicles on the road. One car with a Thermal Imaging System, and three sport utility vehicles. You will be performing the study in the “fog” condition.

    Slide 4: We are going through this training to make you more comfortable with the study before we begin driving. We will cover the items mentioned on this slide. I want to stress that if you have any questions, please stop and ask at any time.

    Slide 5: The Smart Road is perfect for testing of this type. It is completely closed off, making it safe for both drivers and experimenters.

    Slide 6: This is a picture of part of the Smart Road during daytime.

    Slide 7: You will drive a total of four vehicles tonight. Each vehicle might include more than one configuration of Vision Enhancement Systems for a total of 6 different configurations. Five of those configurations are headlamps and the 6th configuration is an Infrared-Thermal Imaging System. This last one is a Heads Up Display positioned over the steering wheel. You will have the opportunity to practice with this system tonight.

    Slide 8: Your primary responsibility is to drive safely. We are also interested in how far away drivers can detect and recognize objects along the road with these Vision Enhancement Systems. We will explain what we mean by detection and recognition shortly. However, I would like to show you this.

    Show them the button

    I will ask you to hold a button like this during the study in your hand while driving. You will press the button like this.

    Press the button

    When you press this in the car, you will hear a beep.

    Slide 9: Detection is when you can just tell that something is on the road in front of you. You cannot tell what the object is but you know something is there. Detection is important while driving since it prepares you to possibly make an evasive action.
    As soon as you detect an object, please press the push button.

    Slide 10: Recognition is when you not only know something is there but you also know what it is. This is important to help you decide how best to avoid the object. For instance, if you see an object in the road and then realize it is a dog, you know that the object can move unpredictably and you need to slow down greatly and likely swerve to avoid it. If however you see an object and it is a box you know the object is not likely to move and slowing down a little and swerving will likely be sufficient.

    When you can accurately recognize an object, I would like you to press the push button and identify the object verbally at the same time. You will need to be specific when you identify. If you see an object, you will need to tell me what the object is.

    For example,

    “I see a Person”

    “I see a Cyclist”

    If you perform an Unsuccessful Recognition, you can press the push button again.

    Slide 11: Dynamic objects include pedestrians and cyclists. The pedestrians will be people walking either along the road or across the road; the cyclists will be riding a bicycle across the road. We will see pictures of these objects shortly.

    Slide 12: Here are pictures of the objects. They will not look exactly like this in the road since these were taken during the day. However, this should give you a good idea of what they will look like.

    Slide 13: We will also have some questions for you to answer. As soon as you are done with a Vision Enhancement System, you will evaluate it. Therefore, after you see the objects with each VES, I will ask you this series of questions (show questionnaire). We want you to rank your answer on a scale from 1 to 7. One means you strongly agree with the statement. Seven means you strongly disagree with the statement. You can give me any number between one and seven. Your answers may or may not be different for each VES, we just want your opinion on the one you just saw.

    Here is the questionnaire that you will be answering for each VES. Let’s go over each of the statements. Please, feel free to stop me at anytime, and ask as many questions as you want. (Read and explain each statement.)

    Slide 14: Go over main points.

    Slide 15: Do you have any questions?
    Answer any questions.

    Shortly we will have you drive one of the experimental vehicles to help familiarize you with the Thermal Imaging System. This uses a heads up display that is projected onto the windshield just below your field of view. The Thermal Imaging System is not intended to be used alone instead it is supposed to accompany your normal driving. Be sure to view the road as your normally do while also using the heads up display.

    Show them diagram.

    This is a diagram of the course for tonight’s training.

    While reading the following section, point out the path that the participant is supposed to follow for the training.

    First drive to the road section. The speed limit for this portion is 25 mph. On this section you will be able to see how things like pavement markings show up in the heads up display. At the turnaround of the road section you need to pull to the far right-hand side of the shoulder and stop the car just past the cone. Then turn the steering wheel fully to the left before beginning the U-turn. Be sure to look for traffic approaching from both directions.

    We will now proceed to the gravel lot. When entering the gravel lot, between the two cones, watch for traffic coming from the right. Once on the gravel lot the speed limit is 15 mph. You will then drive through two more cones driving parallel to the white line on your left. Here you will see one of the objects involved in the experiment and how it appears in the heads up display. Then make a U-turn around the cone at the end of the white line and leave the gravel lot and proceed to the road section.

    You will repeat this process seeing different object two more times. This will conclude the training for today.

    Any questions?

  10. Take the participant to the IR–TIS vehicle. Orient them to the vehicle.
    • You need to have them start the vehicle before orienting them because the seat and wheel move when you start it. Be sure to warn the participants of that before you start the car.
    • Button on left side of seat moves seat up and down, back and forth (show button).
    • Button for the steering wheel moves the wheel up and down, in and out.
    • There are many lights. The only ones they need to worry about are the speedometers- analog and digital (point each out). The subject is free to use whichever they feel most comfortable with.
    • Turn on the headlights all the way (two clicks). Make sure they are on before you get in the passenger seat.
    • Show the participant how to adjust the interior lights. If necessary, help them to adjust it by asking them to tell you when it is comfortable.

  11. Turn on the HUD and adjust brightness.
    • There are two controls used to power and adjust the HUD, located to the left of the steering wheel and under the dash board. The right control, an up/down sliding switch, is used to power the display. The display is powered “on” when the sliding switch is pulled into the top position and is powered “off” when the sliding switch is pushed down into the lowest position. The position of this sliding switch will change the brightness of the HUD.

  12. Adjust position of the HUD.
    • The left control is used to adjust the vertical position of the display. Press the top or bottom of the switch to move the display up or down in the driver’s field of view, but make sure that the driver can see the display over the top of the steering wheel.

  13. Describe the HUD to the driver.

    The thermal imaging system is composed of infrared technology that “lights up” the road ahead. The idea is to provide the driver with an enhanced view of the roadway ahead when traveling at night. In this vehicle, in addition to your normal tasks of detecting and recognizing, we will ask you to tell us whether your recognition was made using the IR system or through the windshield using only the headlights. For example, you may make a detection (I see something), and when you are able to recognize the object (I see a person) include ‘using the IR system’ or ‘using the headlights’ at the end of the statement (i.e. ‘I see a person using the IR system’). This additional task will only occur in this vehicle when the IR system is in use.

  14. Instruct/assist the driver through 3 laps of the training course.

    • Ask driver periodically to describe what they can see using the HUD.

  15. Take Eye Height Measurements on all vehicles that are available.
    • To do this, first explain to the participant that you are going to make a mark on the window as to where their eye level is located. Instruct them to adjust their seat to where they think they will be comfortable. Once they are situated, tell them to look ahead, relax, and stay as still as possible. Close the door and take the measurements.
    • Use the level (located in valet box) to assess participant’s eye position. Once you have found their eye position mark a “+” on the glass (using a dry-erase marker).
    • Using the “+” as a reference point, take measurements (horizontal and vertical).
    • Take vertical measurement with metal end of tape measure down where the glass intersects with the black plastic.
    • Take horizontal measurement with metal end of tape measure to the right where glass intersects with black plastic.


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