General Knowledge · page 19 of 19
General Knowledge questions 361–376
Part of the 376-question General Knowledge pool. Each answer cites the FMCSA CDL Manual or the federal rule it comes from.
Practise these as a timed setHow long must a carrier keep its accident register?
The register lists the date, place, driver, injuries, fatalities and any hazardous material release, and it is held for three years.
49 CFR § 390.15 · Assistance in investigations and special studies · verified 2026-09-08
How long before performing safety-sensitive work must alcohol use stop?
The pre-duty rule bars safety-sensitive work within four hours of using alcohol, separately from the 0.04 concentration limit.
49 CFR § 382.207 · Pre-duty use · verified 2026-08-14
How long after a crash requiring a test may a driver not use alcohol?
Drinking after a reportable crash would destroy the test result, so the ban runs eight hours or until the test happens, whichever comes first.
49 CFR § 382.209 · Use following an accident · verified 2026-08-14
When may a driver work while using a prescribed controlled substance?
The prescriber must know the driver's history and advise that the substance will not affect safe operation; a prescription alone is not enough.
49 CFR § 382.213 · Controlled substance use · verified 2026-08-14
What test must be passed before a driver first performs safety-sensitive work?
The employer must hold a verified negative controlled substances result before using the driver; pre-employment alcohol testing is optional.
49 CFR § 382.301 · Pre-employment testing · verified 2026-08-14
What happens immediately after a driver violates the testing rules?
A driver who has engaged in prohibited conduct may not perform safety-sensitive functions, and the return-to-duty process is what restores them.
49 CFR § 382.501 · Removal from safety-sensitive function · verified 2026-08-14
What must a CDL holder do after violating the drug and alcohol rules?
The driver must tell every current employer in writing before performing safety-sensitive work again, unless that employer is the one that documented it.
49 CFR § 382.415 · Notification to employers of a violation · verified 2026-08-14
What does the on-duty use rule prohibit?
Use during safety-sensitive functions is barred outright, which is separate from the four-hour pre-duty window and the 0.04 concentration limit.
49 CFR § 382.205 · On-duty use · verified 2026-08-14
What is the minimum age to drive a commercial vehicle in interstate commerce?
Interstate driving requires 21, along with enough English to read signs, answer officials and complete reports and records.
49 CFR § 391.11 · General qualifications of drivers · verified 2026-08-14
Under the general federal vision standard, what distant visual acuity is required in each eye?
The general standard requires 20/40 in each eye, 20/40 binocular acuity, and at least 70 degrees of horizontal field in each eye. A separate alternative vision standard may apply to some drivers.
49 CFR § 391.41 · Physical qualifications for drivers · verified 2026-08-14
Which colors must a driver be able to recognize?
Traffic signals and devices use standard red, green and amber, so color recognition is part of the physical qualification standard.
49 CFR § 391.41 · Vision standards · verified 2026-08-14
How is the hearing standard measured?
The better ear must perceive a forced whisper at five feet, or show no more than 40 decibels average loss on an audiometric test.
49 CFR § 391.41 · Hearing standards · verified 2026-08-14
Who is allowed to perform the DOT medical examination?
The examination must be done by a medical examiner listed on the National Registry, with narrow exceptions for the vision portion and for veteran drivers.
49 CFR § 391.43 · Medical examination; certificate of physical examination · verified 2026-08-14
How often must most drivers be medically examined and certified?
Twenty-four months is the standard interval, but insulin-treated diabetes or a vision exemption shortens it to twelve.
49 CFR § 391.45 · Persons who must be medically examined and certified · verified 2026-08-14
What happens if illness or injury impairs a driver's normal duties?
An impairment of the ability to perform normal duties triggers a new examination, regardless of how much time the current certificate has left.
49 CFR § 391.45 · Re-examination after impairment · verified 2026-08-14
What disqualifies a driver under the general qualification rule?
A driver may hold a commercial license from one jurisdiction only, alongside being medically qualified and not otherwise disqualified.
49 CFR § 391.11 · General qualifications of drivers · verified 2026-08-14
