We here in Auckland, New Zealand do not have an abattoir which kills and processes only halaal meat.

Answer

The problem develops right from the beginning at the abattoir. The entire system of killing and slaughtering is un-Islamic. In all probability the animals are brutally stunned prior to slaughter. This is haraam. The meat transported in the haraam manner described by you is not halaal. For the meat to be halaal it is necessary for 100% Muslim supervision from the point of slaughter until the time it reaches the Muslim butchery/ consumer. The truck driver who transports the meat should be a reliable Muslim. Or if the driver is a non-Muslim, then a Muslim has to compulsorily accompany the truck until, the delivery point is reached. It is also imperative for the halaal meat to be stored separately at the abattoir and the cold rooms have to be fully under the control of Muslim supervisors who should have the keys of the cold rooms in their possession. If the keys are in the possession of the non-Muslim owners and there is no 24 hour Muslim supervision at the premises where the meat is stored, then such meat is not halaal for Muslims.

If the trucks are cleaned under Muslim supervision and there is a Muslim supervisor who accompanies the meat from the place where it is slaughtered to the Muslim butcheries then it will be lawful. However, people of Taqwa will not consume even such halaal meat which has been transported in trucks which also carry pigs regardless of the trucks being cleaned.