According to the Roads and Traffic Authority (NSW), CB and two-way radios are not banned for drivers:
300 Use of hand-held mobile phonesResearch has shown that talking on a phone impairs driving ability. It is not holding the phone in hand that is the problem, but having a conversation. Hands free phones cause similar impairment to hand held telephones. However, having a conversation with someone in the car may cause less impairment and conversing with someone in an adjacent car, as was the case in Top Gear, may be less of a problem.
(1) The driver of a vehicle (except an emergency vehicle or police vehicle) must not use a hand-held mobile phone while the vehicle is moving, or is stationary but not parked, unless the driver is exempt from this rule under another law of this jurisdiction.
Note Emergency vehicle, park and police vehicle are defined in the dictionary.
(2) In this rule:
mobile phone does not include a CB radio or any other
From: Australian Road Rules
One area which appears to have not been researched is the impairment from two way radios. Most two way radios are "simplex", that is the radio can only transmit or receive, it cannot do both at once. As a result the two parties have to take turns speaking and there are usually pauses in the conversation between. This makes for a stilted and unnatural conversation, but perhaps this reduces driver distraction.
Hands free kits for mobile phones in cars try to reproduce the free flowing two way conversation of a hand held phone. In practice this is limited by the noise level in the car and positioning of speakers. Less sophisticated kits, and those not well fitted, effectively operate as automatically switched simplex radios, cutting off the audio of the remote party while the driver is speaking. This is normally seen as a problem, but perhaps it increases safety.
Some CB Radios have the option of a tone at the end of a transmission to indicate the other party can now speak (commonly called "Roger Beep"). It may be useful to include this in hands free car kits to indicate to the remote party that the driver has finished speaking.
While the research is not clear on this point, some indicate that conversations with passengers in cars are less impairing as the passenger can see the traffic situation and so know when not to distract the driver. It may therefore be that a videophone showing the traffic, or a phone which detects the driver is busy and sends a synthetic voice or tone to say "driver busy" might help. Such a system might use a tone to indicate to the driver that it is not a good time to talk, or even switch off the microphone to stop them. The phone could detect when there is frequent breaking and use of turn signals, to indicate a high driver workload. Some hand held telephones, such as the iPhone, have accelerometers built in which could be used to to detect when the car is manoeuvring and so it is less safe to talk.
A simpler alternative might be to place a "Push to Talk" button on the car steering wheel. As with a two way radio, this button would need to be held down while the driver was speaking on the telephone. This would have the advantage that the driver would be only able to hold the button down and speak, when the car was proceeding in a uniform heading. As soon as the moved their hands on the wheel to change direction, the button would be released. This should have the effect of training the driver to not talk when manoeuvring.