AS THE PILOT NEARED THE AIRPORT FOR LANDING, HE MANEUVERED ABRUPTLY TO AVOID COLLIDING WITH A DEPARTING AIRPLANE. HE THEN EXECUTED AN APPROACH TO THAT RUNWAY BENEATH HIS WING. ON FINAL, HE OBSERVED THE RUNWAY TO BE BLACKTOP WITH NO MARKINGS. IN THE FLARE, HE OBSERVED THE RUNWAY DID NOT APPEAR TO BE FINISHED. THE AIRPLANE TOUCHED DOWN SHORT OF THE RUNWAY UNDER CONSTRUCTION IN A SOIL AREA RIPPING OFF THE GEAR. THE PILOT STATED HE HAD CHECKED THE NOTAMS AND WAS AWARE THAT THE N-S RUNWAY WAS CLOSED FOR CONSTRUCTION. HE INDICATED THAT THE EARLIER NEAR-COLLISION HAD STARTLED HIM AND HE LANDED ON THE FIRST RUNWAY HE HAD IN SIGHT. IN ADDITION, THE CLOSED RUNWAY WAS MARKED BY A CROSS ON THE SOIL 50 FT BEYOND EACH END USING PERFORATED ORANGE PLASTIC COMMONLY USED FOR CONSTRUCTION BARRIERS. THE PILOT HAD A MEDICAL WAIVER FOR PARTIAL COLOR-BLINDNESS TO RED AND GREEN.