Where our questions come from
Every question is written by HighwayQuiz in our own words from the official handbook it belongs to, and names the handbook, edition and section it is based on. CDL questions also cite the federal rule behind the answer. Where the handbook and a newer federal rule differ, the federal rule wins. We do not copy questions from the DMV or from other practice sites.
Pictures and sounds
Road signs, gauges and teaching diagrams are drawn by HighwayQuiz from the MUTCD and the handbook. Warning sounds are generated in your browser. Photos and placard images come from Wikimedia Commons under the licenses below.
- Orange diamond placard with an exploding-bomb symbol, the word EXPLOSIVES, 1.1 and the number 1 at the bottom: United States Department of Transportation, Public domain
- Red diamond placard with a flame symbol and the words FLAMMABLE GAS: United States Department of Transportation, Public domain
- Green diamond placard with a gas cylinder symbol, the words NON-FLAMMABLE GAS and the number 2: United States Department of Transportation, Public domain
- White diamond placard with a skull and crossbones, the words POISON GAS and the number 2: United States Department of Transportation, Public domain
- Red diamond placard with a flame symbol, the word FLAMMABLE and the number 3: United States Department of Transportation, Public domain
- Diamond placard with vertical red and white stripes, a flame symbol, the words FLAMMABLE SOLID and the number 4: United States Department of Transportation, Public domain
- Blue diamond placard with a flame symbol, the words DANGEROUS WHEN WET and the number 4: United States Department of Transportation, Public domain
- Yellow diamond placard with a flame-over-circle symbol and the word OXIDIZER: United States Department of Transportation, Public domain
- White diamond placard with a skull and crossbones, a blank white center panel and the number 6: United States Department of Transportation, Public domain
- Diamond placard, yellow on top and white below, with a trefoil symbol, the word RADIOACTIVE and the number 7: United States Department of Transportation, Public domain
- Diamond placard, white on top and black below, with liquid dripping on a hand and a bar, the word CORROSIVE and the number 8: United States Department of Transportation, Public domain
- White diamond placard with seven black vertical stripes on the top half, a blank white center panel and the number 9: United States Department of Transportation, Public domain
- Red diamond placard with a flame symbol, a white center panel showing the number 1203, and the number 3: United States Department of Transportation; ID number added by HighwayQuiz, Public domain
- An uphill gravel escape lane beside a mountain highway: Travisl, Public domain
- The flat round coupling plate mounted on the back of a tractor: Photohelp13, CC BY-SA 4.0
- The underside front of a semi-trailer showing a steel pin pointing down: Sterkebak, CC BY 3.0
- A round metal canister mounted near a truck axle with an air hose attached: Panoha, CC BY-SA 3.0
- A short single-axle frame with a coupling plate and a tow bar: Amada44, Public domain
- A tractor pulling two short trailers on a highway: D'oh Boy (Mark Holloway) from Beatty, Nevada, USA, CC BY 2.0
- A tractor pulling three short trailers on a highway: D'oh Boy (Mark Holloway) from Beatty, Nevada, USA, CC BY 2.0
- A tractor pulling a cylindrical tank trailer: Xnatedawgx, CC BY-SA 4.0
- A truck displaying diamond-shaped hazard placards: Oaktree b, CC BY-SA 2.5 ca
- The side of a yellow school bus with a red octagonal stop arm swung out: NTSBgov, Public domain
- Inside a bus: a side window marked as an emergency exit with a release handle: SetoMonamer, CC BY-SA 4.0
- Steel chains fitted around a large truck tire: Oregon Department of Transportation, CC BY 2.0
- Red reflective warning triangles set out on a road: Roulex 45, CC BY-SA 3.0
- A low steel railroad bridge on stone piers over a city street: Washuotaku, CC BY-SA 4.0
- A highway descending a mountain with a steep-grade warning sign for trucks: formulanone from Huntsville, United States, CC BY-SA 2.0
- A large intercity passenger bus: Hikki Nagasaki, Public domain
We re-check questions against each new handbook edition and federal rule change.