[Federal Register Volume 61, Number 109 (Wednesday, June 5, 1996)]
[Proposed Rules]
[Pages 28547-28550]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-14041]



Federal Highway Administration

49 CFR Part 391

[FHWA Docket No. MC-96-4]

Proposed Research Plan on Vision Standard

AGENCY: Federal Highway Administration (FHWA), Department of 

ACTION: Notice; request for comments.


SUMMARY: The FHWA is requesting comments on a proposed research plan to 
explore performance-based alternatives to the existing vision standard 
for drivers of commercial motor vehicles (CMV). The findings of this 
research effort may result in the modification of that standard. The 
FHWA seeks comments on all aspects of the research plan, including its 
scientific merit, likelihood of achieving its objective, methodological 
validity, consideration of all relevant research, and other practical 
    The FHWA is also announcing a public hearing to obtain comments on 
the proposed research plan. The hearing is designed to obtain public 
input on the proposed research plan, not to determine the status of 
individual drivers or participants in the vision waiver program. At the 
hearing, the FHWA does not intend to discuss the status, results, or 
recommendations that might result from the vision waiver program.
    A review of scientific literature relevant to the vision standard 
and the proposed research plan have been placed in FHWA Docket MC-96-4. 
In addition, both documents are accessible electronically through the 
Federal Highway Administration's World Wide Web (WWW) site.

DATES: The comment period will remain open until further notification 
in the Federal Register. The public hearing will be held on August 9, 
1996, at the Chicago O'Hare Marriot, 8535 West Higgins Road, Chicago, 
IL, 60631, (312) 693-4444.

ADDRESSES: Submit written, signed comments to FHWA Docket MC-96-4, Room 
4232, HCC-10, Office of the Chief Counsel, Federal Highway 
Administration, 400 Seventh Street., SW., Washington, DC 20590.
    The literature review and proposed research plan are on the Federal 
Highway Administration's World Wide Web site (http://
cti1.volpe.dot.gov/ohim/whtnewhd). Users with questions about the 
operation of the WWW site should call the FHWA Computer Help Desk at 
(202) 366-1120.

FOR FURTHER INFORMATION CONTACT: Mr. Charles Rombro, Federal Highway 
Administration, Office of Motor Carriers, 400 Seventh Street SW., room 
3104, Washington, DC 20590, telephone (202) 366-5615. Office hours are 
from 7:45 a.m. to 4:15 p.m., e.t., Monday through Friday, except 
Federal holidays.

SUPPLEMENTARY INFORMATION: The FHWA is authorized by statute to 
establish minimum physical qualification requirements for drivers of 
commercial motor vehicles. 49 USC 31502.
    The Congress provided the FHWA with complementary regulatory 
authority with the enactment of the Motor Carrier Safety Act of 1984, 
codified in substantial part at 49 U.S.C. 31101-31162. This Act 
directed the Secretary to establish minimum safety standards to ensure, 
inter alia, that ``the physical condition of operators of commercial 
motor vehicles is adequate to enable them to operate such vehicles 
safely * * *.'' 49 U.S.C. 31136(a)(3).
    The physical qualification regulations for CMV drivers in 
interstate commerce are found at 49 CFR 391.41. The qualification 
standards cover 13 areas which directly relate to the driving function. 
All but four of the standards adopted by the FHWA permit the individual 
determination of a driver's qualification. A person's qualification to 
drive is determined by a medical examiner who is knowledgeable about 
the on-the-job functions performed by a commercial driver and whether a 
particular condition would interfere with the driver's ability to 
operate a CMV safely. In the case of vision, hearing, insulin-using 
diabetes and epilepsy, the current standards are absolute, providing no 
discretion to the medical examiner.
    The current vision standard specifies that drivers must meet the 
following three conditions:
    1. distant visual acuity in each eye of at least 20/40, and distant 
binocular acuity of at least 20/40 in both eyes; and
    2. field of vision of at least 70 degrees in the horizontal 
meridian of each eye; and
    3. the ability to recognize the colors of traffic signals.
    In order to improve protection for the public and provide for 
individual determinations of fitness to drive wherever possible, the 
Agency is interested in developing performance-based standards. In a 
Federal Register notice on the vision waiver program published on 
November 17, 1994 (59 FR 59386), the FHWA announced its intention to 
initiate a research plan to ``develop parameters for performance-based 
visual standards for all commercial drivers.'' 59 FR at 59389. The 
research plan outlined in this notice is designed to move the Agency 
towards a performance-based vision standard. This standard would 
incorporate the measurement of those visual capabilities deemed 
necessary for the safe operation of commercial vehicles. The research 
discussed below is designed to relate specific visual functions to 
specific driving tasks, such as the ability to stay in a lane. The 
standards would still be prescriptive in that they would establish a 
minimum score which individuals would be required to meet to be allowed 
to drive; however, the scoring scheme would be based on detailed 
research on the visual attributes required to safely operate a CMV.

Research Plan

    The FHWA has developed a proposed research plan, an outline of 
which is provided below.


    The FHWA's review of the existing literature on vision and driving 
research led the FHWA to the following conclusions:
    1. The current testing standard lacks criterion, or predictive, 
validity; that is, it is not clear that central visual acuity by itself 
is a good predictor of safe driving. This detracts from the perceived 
fairness of the standard. The principal shortcoming of the current 
standard is the emphasis on central visual acuity, which is a measure 
of how well an individual can discern static images in the center of 
vision under conditions of high luminance. Since many driving 
situations involve dynamic images under low luminance, other visual 
capacities may be equally

[[Page 28548]]

or more important than central visual acuity.
    2. Improving the criterion validity of the vision standard would 
most likely require testing a broader array of visual capabilities than 
those included in the current standard.
    3. There is no assurance that a standard based on a better 
understanding of the relationship between different visual capabilities 
and driving would result in a significant, measurable improvement in 
safety, in part because vision is a contributor to only a small number 
of crashes. CMV drivers comprise a small proportion of drivers, and are 
represented in a small proportion of crashes, not all of which are 
caused by failures of visual performance as currently measured. 
However, the weak observed causal relationship between vision and 
crashes may be a shortcoming with the current measurement of vision. It 
is therefore possible that the measurement of other visual functions 
could reveal a more significant and direct connection between vision 
and driving ability.
    The goals of the proposed research are threefold:
    1. Establish a list of visual performance parameters that appear to 
hold promise as a basis for a new standard, and design or adapt 
performance tests to measure these capabilities.
    2. Evaluate the predictive validity of these tests.
    3. Based on the results of these tests, establish a trial vision 
standard, and test that standard to evaluate its validity.

Outline of the Research Plan

    The research contains both a long-term and a short-term track. The 
Agency may decide to conduct either of the two tracks individually, 
both tracks simultaneously, both tracks consecutively, or neither 
track. The emphasis of the short-term plan is to build on existing 
knowledge to develop an improved vision test, with the goal of adding 
two or three existing vision tests to the battery currently tested. 
This track does not call for significant new research, but rather seeks 
to take advantage of already completed work. This track could result in 
the development of a two-tier standard, with an expanded battery of 
tests in the first (screening) tier, and various administrative 
measures proposed for the drivers who do not pass this first tier. 
Administrative measures may include provisional or restricted licenses, 
waivers, or in-use monitoring of drivers.
    The long-term plan consists of new research and analysis, which may 
lead to the development of a new standard.
    Two phases of the research are already complete. The short-term 
research consists of six or seven additional stages, as explained 
below. The long-term research would consist of four additional phases.
    The phases of the research are described below.

Research Completed or Underway

    1. Development of the research plan. This phase is complete, and 
the work described below is the output of the planning effort. This 
phase describes the proposed approaches in some detail; certain 
elements are necessarily unspecified. For example, the choice of 
specific visual function tests cannot be made before further research 
and analysis are complete.
    2. Design of testing strategy. This phase involves selecting and 
developing the form of the candidate tests, as well as the measures 
that the tests must predict. This phase is currently underway.
    Selecting the candidate tests includes a general selection of 
visual functions to be tested, an inventory of the tests already 
available, and identification of new tests to be developed and 
validated. Tests should have broad acceptance and stable underlying 
population norms. The protocols for testing should be developed and 
accepted by researchers and testers, and results must be stable 
regardless of who administers the test. Acceptable population norms are 
necessary if a test is to be used to classify individuals based on 
``normal'' results in the population of CMV drivers.
    While some tests, such as the Snellen Letter test of visual acuity, 
are broadly accepted and have stable and well understood population 
norms, other tests of potentially important visual functions do not 
meet these standards. These latter tests would have to be evaluated. 
The evaluation would consider how important the visual function is in 
the driving task, the extent to which the test results are stable and 
reliable, and how readily the tests can be developed for broad usage.
    Our review of the literature has led us to focus on the following 
visual functions as most relevant to the driving task: static acuity, 
contrast sensitivity, dynamic acuity, working field of view, dark 
focus, low contrast acuity, glare sensitivity, and vection.
    The FHWA, with the assistance of a contractor, is in the process of 
identifying the behaviors that the tests must predict--the measures of 
effectiveness. This will be followed by the systematic development of 
measures to be validated by the visual performance tests. 
Theoretically, we would prefer to be able to relate a driver's 
performance on vision tests to an actual driving record, especially the 
driver's accident record. Because of the infrequency of accidents, 
however, we would need to test a very large number of drivers over many 
years to obtain reliable results. In addition, a ``clean'' experiment 
would require that we allow drivers who we suspect may be deficient in 
some key visual function to operate CMVs on the road. Allowing 
potentially hazardous drivers to operate CMVs poses obvious safety 
problems, and contravenes the FHWA's mandate to protect highway safety.
    As a proxy for accidents, we are developing a list of candidate 
visually- related driving behaviors. This is a reasonable proxy because 
it is the driver's behavior that connects visual deficiencies and 
accidents. An example might include the time a driver takes to initiate 
a braking maneuver. Behaviors will be selected for further testing 
based on their likely validity and practicality. Since we will not be 
measuring accidents, it is especially important that the measures are 
closely related to driving performance.
    After choosing behavioral measures, the Agency will develop test 
procedures and protocols.

Proposed Short-Term Research

    3. Define criteria for selection of vision tests. The likely 
criteria will include: test availability with little or no 
modification, scientific reliability, construct validity, practicality 
of use in a testing environment, and acceptability to researchers and 
testers. While other criteria are possible, the FHWA anticipates that 
the factors listed above will be used to screen tests for their 
suitability for further research. Much of the work required to define 
the criteria has already been completed under tasks 1 and 2.
    4. Select candidate tests. The researchers would select 3 to 5 
candidate tests for further research. The tests would have to meet the 
criteria identified above. The researchers would determine which tests 
meet these criteria through a survey of the scientific community and 
other interest groups, and through the literature review conducted in 
task 1.
    5. Design demonstration/evaluation project. This task consists of 
specifying the details of the testing procedures. The researchers would 
select a site for the tests, choose criteria for obtaining

[[Page 28549]]

test subjects, and detail the protocols for administering the vision 
    6. Conduct empirical evaluation of operational feasibility. This is 
the actual testing component, in which the drivers will be tested in an 
operational setting to ensure that the new test battery's facilities 
requirements are not excessive, its personnel needs are realistic, and 
that the tests can be administered, scored, and interpreted in a timely 
fashion by the individuals responsible for administering the tests.
    7. Conduct empirical evaluation of validity of pass/fail criteria 
for those candidate vision tests without sufficiently demonstrated 
construct validity. The first step in this task would be to define the 
study sample. The most likely sample would be age-matched 'visually 
impaired' and 'visually unimpaired' subjects on the candidate tests 
(all subjects would be required to hold a valid CDL). The researchers 
would then conduct the vision and performance tests and analyze the 
differences in performance between the two groups. Differences would be 
measured relative to alternative cutoff scores, so that the Agency 
could determine the significance of choosing different levels of 
    The FHWA could decide to bypass task 7, the empirical validation 
phase, if it determines that enough information currently exists to 
establish a new standard, or that additional research would be unlikely 
to lead to significant safety improvements. The Agency estimates that 
skipping task 7 would reduce the time needed to complete the research 
by one year.
    8. Recommend tests and pass/fail criteria. Based on the work 
completed above, the researchers would propose specific tests to be 
added to the existing testing battery and cutoff scores for each test.
    9. Convene interest groups to develop operational recommendations. 
These groups would include motor vehicle licensing administrators, 
researchers, industry associations, and safety advocates.

Proposed Long-Term Research

    10. Design of tests and protocols. This includes developing the 
visual performance and behavioral tests specified in task 2, generating 
initial data from a pilot test, and designing draft protocols to be 
used in later stages.
    The visual function test would include some combination of existing 
and new tests. The Agency would arrange the practical testing aspects, 
including the purchasing and licensing of tests, acquiring any software 
and documentation required, and developing the test protocols.
    Pilot tests would be conducted on a small sample of drivers to 
verify test reliability and suitability for large scale testing. The 
Agency would modify procedures and protocols as appropriate. Upon 
completion of the pilot test, the FHWA would conduct the visual 
function tests on a medium-sized sample of drivers. The sample would be 
large enough to allow the Agency to analyze test score characteristics. 
Use of pilot tests would allow the Agency to ensure that a test would 
produce useable results. In addition, correlation between tests may be 
observed, in which case some tests may be eliminated from the final 
battery as redundant.
    For driver behavior measures, the agency would develop simulator 
materials and closed-course testing procedures. To the extent possible, 
the FHWA would employ procedures which can be used on multimedia 
personal computers with a minimum of special equipment. The Agency 
would develop hardware, software, and testing protocols.
    The extent of the work performed in this task will depend on 
whether the Agency conducts the short-term research. Some of the work 
outlined above may be conducted in task 2 of the short-term track. If 
that is the case, we will not repeat the work in this task.
    11. Laboratory Simulation. This phase consists of evaluating the 
candidate tests in a controlled setting, to identify and correct any 
problems in the testing or protocols. This step is essentially a 
``dress rehearsal'' for the full scale test. Because the next phase is 
the most costly in terms of time and resources, this phase was designed 
to allow the Agency to make a final decision about whether to continue 
with the research prior to commencing with the next phase of the plan, 
the full testing and evaluation.
    A limited number of subjects would be given all the proposed visual 
function and driver behavior tests. The results of these tests would be 
analyzed extensively, including relationships between and among both 
sets of tests. The analysis would address the following issues:
    a. Are the distributions of scores useable?
    b. Is there sufficient variance to discern relationships between 
visual and driving tests?
    c. How well do visual tests predict driving results, by themselves 
and in combination with other tests? How much of the variance between 
individuals in driving behavior can the vision tests explain?
    The agency would also conduct a preliminary cost-benefit analysis. 
In addition to projecting the cost of the next phases of the research 
program, the analysis would estimate the cost of implementing a new 
vision standard and the possible safety benefits.
    12. Validation Testing. This phase consists of two sequential 
activities, test preparation and data collection, the crux of the 
proposed research.
    Test preparation includes selection and configuration of test 
sites, plus selection and preparation of subjects. The site (or sites) 
selected must have, or be able to accommodate, a driving simulator, a 
closed test course, and a road test course. Site preparation includes 
configuring the testing equipment for the site, surveying the road test 
course, and preparing and deploying signs and obstacles for the closed 
test course. Preparation of the subjects consists of briefing the 
participants and pre-testing them for the visual measures.
    A final closed-course pilot test would then be conducted, using a 
small number of drivers. This would provide the Agency with a final 
opportunity to modify the test procedures.
    Validation testing would probably include at least two distinct 
activities, simulation and closed-course testing, and would possibly 
also include controlled road testing. Variables would be strictly 
controlled in these simulation tests to ensure the accuracy and 
reliability of results. The FHWA expects that the simulators used for 
this phase would be more sophisticated, with higher video resolution 
than those used in the previous pilot test.
    Closed-course testing would be used to test drivers under low 
visibility conditions. This is difficult to imitate on a simulator and 
is unsafe to test on the road.
    If road testing is conducted, it would consist of non-intrusive 
instruments to record driver responses, such as eye movement patterns, 
blink rates, pupil diameter, and fixation points. This information, 
combined with data on the roadway obstacles, provides a stream of data 
related to working field of view, detection time, and how drivers react 
to critical events. The road test would be conducted under normal 
driving conditions to assure that the results are generalizable to 
normal CMV operating practices. There are a number of hurdles to using 
a road test, including the need to perform the test for an 
impractically long period to obtain sufficient data, and the 
possibility that drivers would modify their behavior if they are aware

[[Page 28550]]

that they are under observation. The FHWA would decide whether to 
conduct the road test after analyzing the results obtained in the 
simulation and closed-course tests.
    13. Standard Development. The results of the preceding task would 
be analyzed for validity, reliability, and practicality. If the results 
of the validation testing justify specification of a new standard, a 
decision framework for that standard would be constructed.

Specific Questions

    The FHWA is specifically interested in comments addressing the 
following issues:
    1. Are there any methodological shortcomings in the research plan 
outlined above that need to be addressed?
    2. Is the plan likely to meet the objective of leading to an 
improved, performance-based vision standard?
    3. Does the plan reflect an understanding of the current literature 
and consider its implications?
    4. Is the plan capable of adequately addressing practical matters, 
such as the cost of any new testing machinery developed, the level of 
training required to conduct new tests, and the time needed to take 
    5. Has this type of research been conducted in other professions? 
What were the results?
    6. Should the FHWA proceed with the short-term plan, the long-term 
plan, both, or neither?
    7. Should the FHWA proceed with an alternative plan? If so, 
describe that plan.

Current Status of the Research Program

    The FHWA is currently in the midst of step 2 of the research plan, 
which consists of inventorying existing tests and evaluating them 
against a number of criteria, including their cost, which visual 
functions they measure, overlap between different tests, and the amount 
of training required to conduct the tests.

Format of Public Hearing

    The FHWA announced in the November 17th notice (59 FR 59386) its 
intention to hold a public hearing to discuss the research plan. The 
public hearing will be held on August 9, 1996, at the Chicago O'Hare 
Marriot, 8535 West Higgins Road, Chicago, IL 60631, (312) 693-4444. The 
hearing will begin at 8:30 a.m. and conclude at 4:30 p.m.
    Individuals wishing to speak at the hearing should contact the FHWA 
at the address or phone number listed above under the heading ``For 
Further Information Contact.'' Individuals may submit written comments 
in addition to, or in place of, oral testimony. All commentors will be 
limited to ten minutes of oral remarks.
    The hearing will commence with an explanation of the proposed 
research plan, including a brief description of the background to this 
effort, the goals of the proposed research, and the steps of the 
proposed plan. The FHWA will then accept questions from audience 
members, with individuals who have contacted the FHWA given the first 
opportunity to speak.

(49 U.S.C. 31136(a)(3), 31502)

    Issued on: May 20, 1996.
Rodney E. Slater,
Federal Highway Administrator.
[FR Doc. 96-14041 Filed 6-4-96; 8:45 am]