A system similar to bandboxing is permanently in use (in the UK anyway) for airfield vehicles. Their radios operate on UHF, around 450mHz, and the frequencies are "paired" with airband VHF frequencies such that when a vehicle calls the Tower,ite transmits on UHF and this is immediately re-broadcast on the appropriate VHF frequency. Equally, traffic on VHF is re-broadcast on the UHF frequency. Somebody can probably say why they don't simply use VHF radios in vehicles but I was told it was due to licensing problems...?