There are no official published data on volume of traffic carried by the D402 road, however, Hrvatske ceste, the operator of the road, publishes information on average annual daily traffic (AADT) and average summer daily traffic (ASDT) carried by Brestova - Porozina ferry line, connecting D402 and D100 state roads. It may be safely concluded that traffic carried by D402 at least matches those figures.
D402 volume of traffic
Brestova ferry port
Number of vehicles using Brestova-Porozina ferry line (number 334), published by Hrvatske Ceste.