This question relates to

… the maximum speed at which a trailer can be towed under response conditions SES GLR accredited unit (rule 306). For the purpose of the argument let’s assume that we have level 3 swift water technicians responding to persons trapped by rising floodwater,

The driver is a NSW SES level 3 approved driver (lights & sirens) they are towing a boat on a boat trailer.

At what speed should they respond? One piece of advice that has been obtained is not exceeding the “rated” speed of the trailer, (no rated speed displayed on trailer, possibly contact maker).

Also a similar situation could arise with a vertical rescue unit towing a trailer (with VR gear inside) responding to a call same driver authorisation as the above example.

The reference to rule 306 is a reference to the Road Rules 2014 (NSW) r 306.   This is not a blanket exemption from everything to do with driving.  It is an exemption, to the extent it is an exemption at all, from the other rules listed in the Road Rules 2014 (NSW) and not all the rules relating to driving and vehicles are in the Road Rules 2014.    The Road Rules do contain provisions about towing cars or motorcycles (see for example r 294-3 NSW rule: towing restrictions generally) as well as some provisions about towing trailers.  For example r 294-2 provides that a driver must not tow a trailer or other vehicle

… if the laden weight of the towed vehicle exceeds:

(a) the capacity of the towing attachment fitted to the towing vehicle, or

(b) the maximum laden weight for the towed vehicle.

That says nothing about ‘speed’.

Regulation 21 provides that the maximum speed for a ‘vehicle and  trailer combination with a GCM [Gross Combination Mass] over 4.5 tonnes … is 100 kilometres per hour’.  That appears to be the only relevant speed limit in NSW (see also Road and Maritime Services, Towing (u.d)).

Discussion

If there is a rated speed of the trailer then of course you should not exceed that speed. Remember that the most important road rule is don’t crash and don’t kill anyone.  If there is are ‘persons trapped by rising floodwater’ saving their lives does not justify killing someone else.  And if you crash you’re not going to get there to save their life anyway.   If the trailer has a ‘safe’ speed, exceeding that speed, even if you are lawfully entitled to, would not be exercising ‘reasonable care’.  So if the rated speed of the trailer is 80km/h and the speed limit is 100km/h, you don’t need r 306 to travel at 100km/h but you are not taking reasonable care.  If the rated speed for the trailer is 100km/h and the speed limit is 100km/h, r 306 won’t justify travelling at 110km/h as again you are failing to take ‘reasonable care’.

Remember this case from Victoria – Suspended Jail Sentence for Firefighter Involved in a Fatal Accident (October 24, 2009).  There the driver was travelling under the prescribed speed limit but, according to the sentencing judge, ‘there was an “inescapable inference’’ that [the driver], who knew the truck was top-heavy when filled with water, was driving it ‘‘just too fast’’.

In the context of the question I am considering if the weight, load distribution and recommendations of the trailer and vehicle manufacturer suggest a particular maximum speed then travelling over that speed is ‘just too fast’ regardless of the posted speed limit on the road, or the needs of the people to whom you are responding.

Conclusion

Rule 306 gives some exemptions from the road rules but only when it is safe to do so.  The speed at which you should tow a trailer is a matter of safety.  Driving too fast (taking into account the weight of the trailer, how the load is distributed and recommendations from both the trailer and towing vehicle’s manufacturer), regardless of the posted speed limit, cannot be justified and r 306 will not be relevant.