T139 or TW01.7 Temporary Warning Surveying Roll Up Road Signs, referred to as a W1-1.8 Sign in the TCD Rule, is a supplementary plate made of Flexi-lite retro-reflective roll up material, used to indicate that surveying activity in operation. The TW-1.7 Surveying Traffic Sign is used underneath a T1A TW-1 Road Works Sign on Level One New Zealand Roads for Temporary Traffic Management (TTM) and is in the Waka Kotahi Code of Practice (CoPTTM).