It is red and white shaped like a cross.
An X. Because it is a cross for the railroad crossing.
The road sign is a large yellow circle with a black X across the circle. The railroad can also erect their own RR crossing warning signs which consist of a two planks of wood (or other material) configured into a shallow-X or "crossbuck" style sign. These warning signs are painted white with the words "rail road crossing" stenciled on them in black letters.
In North America, they're round.
A large X, referred to as a crossbuck.
Railroad crossing signs are either a white x shape with the words railroad crossing inside of them or a yellow circle with a black x and the letter R on the left and right side.
Yes. some are yellow and shaped circle with black 'X' and R R . and some are just the 'X' shape and white in color with 'railroad crossing' in black. one word for each piece of matieral that is used
An advance railroad sign is round and has a yellow background with a black X and black R's on each side of the X. The sign at the site of the tracks is an X shaped sign that is white with black text and says "Railroad Crossing" with the words crossed on each leg of the X. Crossbuck.See the related link for a site with pictures of US traffic signs.
Warning signs are usually a diamond shape. The color of the sign is yellow in order to caution drivers about an intersection ahead, bicyclists or wildlife that may be near the road.
a triangle
It is a polygon.
Shaped like an X
US standard traffic warning signs are yellow background with black symbols or letters. Traffic warning signs in other countries are generally white or yellow background with a red or black border in a triangular shape. Industrial warning signs are various colors, including OSHA and ANZI standards with orange background and black lettering. A yellow OSHA or ANZI sign would mean "caution" not "warning".