If you find signs in Naviate Traffic that are faulty, please check this library where newly updated signs are uploaded. 

Updated Traffic Signs 

After you have downloaded the sign/signs you require, place them in the appropriate sub-folder in the following path: 

C:\users\public\documents\symetri\naviate\civil3d<version>\<language>\support\NVTraffic

If you can't find the sign you are looking for in the updated library, please contact Symetri Support.