T139 or TW01.7 Temporary Warning Surveying Road Signs, referred to as a W1-1.8 Sign in the TCD Rule, is a supplementary plate, used to indicate that surveying activity is in operation. The TW-1.7 Surveying Traffic Sign is used underneath a T1 TW-1 Road Works Sign and available for Level One or Level 2/3 New Zealand Roads for Temporary Traffic Management (TTM) and is in the Waka Kotahi Code of Practice (CoPTTM).