CE425 PLT TAKES OFF ON TXWY AT LBF.

Narrative

I HAD STOPPED FOR REFUELING AT NORTH PLATTE; NE (LBF). AFTER REFUELING; I INTENDED TO TAXI OUT TO RWY 35 FOR TKOF. AS I TAXIED OUT; I FOLLOWED A TAXI SIGN TO RWY 35. DURING TAXI; A C172 CALLED A WIDE 3 MI BASE FOR RWY 35. I HAD CALLED ON CTAF THAT I WAS TAXIING OUT OF THE RAMP. THE C172 SAID HE WOULD EXTEND HIS PATTERN TO GIVE ME TIME TO BACKTRACK AND TAKE OFF. DUE TO MY EFFORT TO EXPEDITE MY DEP TO MAKE WAY FOR THE C172; I TURNED ONTO WHAT I THOUGHT WAS THE RWY. IT WAS WIDE AND LOOKED LIKE A RWY. AS I WAS APCHING 80 KTS; I REALIZED MY HDG DID NOT READ 350 DEGS. I HAD ROOM TO TAKE OFF AND FELT CONTINUING WAS SAFER THAN TRYING TO ABORT. THE TKOF WAS COMPLETED WITHOUT INCIDENT. AT NO TIME DID I INTERCEPT A RWY; BUT DID CROSS OVER RWY 35 AT ABOUT 300 FT AGL. I ALWAYS CHK MY HDG AGAINST THE RWY; BUT FAILED TO DO SO AT THIS TIME. 1/2 WAY THROUGH THE TKOF; I DID CHK THE HDG AND REALIZED MY MISTAKE. I THINK MY ATTN WAS DISTR WHEN I TRIED TO HURRY MY TKOF TO MAKE ROOM FOR THE C172. AS I REVIEWED THE ARPT DIAGRAM AFTER THE TKOF; I STILL AM CONFUSED AS TO HOW THE TXWY IS DEPICTED ON THE PLATE. THE TXWY OUT OF THE RAMP IS A FAINT LIGHT GRAY AND INTERCEPTS A WIDE STRIP THAT IS USED TO TAXI TO RWY 35. THAT STRIP NOT BEING COLORED THE SAME AS THE OTHER TXWYS IN COLOR GAVE ME THE IMPRESSION IT WAS A RWY. BUT; AFTER CLOSER REVIEW; IT IS NOT NUMBERED. I SUGGEST THAT IT SHOULD BE COLORED THE SAME AS THE OTHER TXWYS ON THE PLATE.