Yes, RUNWAY is a Scrabble word!

Letter values in Scrabble US: R 1, U 1, N 1, W 4, A 1, Y 4.

Is it a valid word?

RUNWAY is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a bar or pair of parallel bars of rolled steel making the railway along which railroad cars or other vehicles can roll
a chute down which logs can slide
a narrow platform extending from the stage into the audience in a theater or nightclub etc.
a strip of level paved surface where planes can take off and land