Curve and Crossroad road plates each measure 9” (25cm) square.

[ks6349]

what does it mean?

Does it mean the diagonal length of the road plate is 25cm?

What is the length of each side?

[Aanchir]

For the most part, measurements in official LEGO set descriptions aren't 100% accurate, but rather rounded down to the nearest whole number. In this case it is saying that each side measures over 25 centimeters and over 9 inches.

To give you a more precise measurement, a single LEGO "module" (e.g. "one stud" in length/width) is 8 millimeters. All road plates are 32x32 modules/studs, so that means they are 25.6 centimeters in length and width. That's equivalent to 10.07874 (or about 10 and 1/16) inches.

[ks6349]

10 minutes ago, Aanchir said:

For the most part, measurements in official LEGO set descriptions aren't 100% accurate, but rather rounded down to the nearest whole number. In this case it is saying that each side measures over 25 centimeters and over 9 inches.

To give you a more precise measurement, a single LEGO "module" (e.g. "one stud" in length/width) is 8 millimeters. All road plates are 32x32 modules/studs, so that means they are 25.6 centimeters in length and width. That's equivalent to 10.07874 (or about 10 and 1/16) inches.

Are the size for road plate the same as the green/blue/grey single color plate?

[weeble1688]

The current set #60237 Curve and Crossroad plates are the dimensions stated by Aanchir, with a studded surface of 6 studs inward from edges/corners.  This is the same size as the green or blue 32x32 stud baseplates, but smaller than the extra-large grey 48x48 studded one.  Indeed, most road baseplates are 32x32 studs, though the width of flat non-studded surface varies depending on the age of the mould used to manufacture the road baseplate.  I hope this helps!