Look sign
Posted at a railroad crossing to tell you to look both ways along the tracks before you cross.
Federal designation R15-8 in the MUTCD, the national standard every state signs to. Mounted on or near the crossbuck at crossings that have no gates or lights.
How to recognise it
This sign is a wide rectangle in white, the standard background for a rule you must obey. A round yellow advance warning, then the white crossbuck at the tracks themselves. The crossbuck has the legal force of a yield sign, which surprises a lot of test takers.
What the test wants you to know
It is a regulatory sign, white with black legend, not a yellow warning, which is the detail that catches people out. It appears at passive crossings where there are no gates or flashing lights, so your own eyes are the only warning system.
Practise it
Reading about a sign is not the same as recognising it in half a second with an examiner watching. Every state road signs test on this site shows the sign and asks you to name it, then shows four faces and asks you to pick the right one.
Railroad Crossing Ahead
Crossbuck
Exempt Crossing
Do Not Stop On Tracks
Multiple Tracks