Don't see the point in tunnels, every second or third truck carries dangerous goods of some sort these days, I thought the idea was to get the big scarry trucks out of town
Apparently while there is no definite with the figures as yet. One the subject of Dangerous Goods, only (now I will stand correct on this) Class 1 and Class 2.1 Dangerous Goods are not allowed in the tunnels and will still have to go through town on what will be the old Highway. Further of those Dangerous Goods vehicles there is on average about 15ish per 24hrs on average. Of those 15 it is believed most of them will already have to go into Coffs Harbour for whatever delivery/pickup they have to do. So they don't count as they already have to go into Coffs Harbour.
So they are working on about 5 Dangerous Goods Vehicles in 24hrs that will still have to use the 'old Highway' which keeps the Council happy as the RMS will continue to maintain the old Highway. Saves the Council trying to get more rates increases to cover cost of maintaining what will still be the busiest road in Coffs Harbour. So those 5 Dangerous Good Vehicles per 24hrs with three tunnels, 2 will be Managed Tunnels as they will be about 450 and 350 meters while the third tunnel 60m (called a Land Bridge so as not to be confused with a Managed Tunnel).
Those two Managed Tunnels may be 24/7 monitored from the Station atop the St Helena Tunnel but will still need a lot of logistics in Coffs Harbour, but the regular scheduled maintenance will be a continuous yearly increasing cost of an unknown sum of millions, including closing the tunnels four times a year etc as they do with St Helena tunnel.
I did wonder if some number cruncher in Treasury will see the justification in that ongoing cost for five Dangerous Goods Vehicles a day. But hey if it makes the noisy minority that live in the most affected area of Coffs harbour happy, apparently cost isn't a concern.