The introduction of an increase of mass limits is a welcomed one, but how it will actually affect industry? Technical Editor Bob Woodward explores the issue.
I remember well the discussions when industry was pressing to progress HML, and the road and infrastructure managers promoted how all these bridges would fail.
This someone developed into a monster called IAP and then suddenly, somehow, these structures got stronger!
Similarly with a need to increase steer axle weights with the introduction of Euro 4 in about 2006, according to road managers, the extra half tonne steer mass was going to result in extensive structure failures.
One industry association proposed a concept that considered a progression of steer axle mass limits from 6.0 tonnes to 6.5 tonnes; then onto to 6.7 tonnes; and 7.0 tonnes.
However, some sectors were so hellbent on a quick fix and getting prime movers legal, so the focus was on a short-term fix. Steer axle mass was progressed from six tonnes to 6.5 tonnes and the failures didn’t eventuate.
All the while some jurisdictions had already recognised a need for seven tonne steer axles (road train) and introduced permit schemes.
The journey to more stringent emission standards and the advent of electric heavy vehicles has brought yet another set of challenges, namely increases in prime mover and truck tare weight.
However, before focusing too much on electric vehicles, it is interesting to note that several of the major passenger automotive manufacturers are stepping back from electric vehicles, exploring hydrogen, bio diesel and even ammonia.
Whilst electric alternatives may find significant application in urban short haul deliveries, I doubt it will be a significant player in long distance heavy freight transport. One supplier has recognised the disbenefits of recharging heavy electric vehicles supplying hydrogen buses to Tasmania and South Australia.
The recently announced amending of regulation that will allow an additional 0.5 tonnes for ‘complying’ Euro 6 single-steer and twin-steer axle vehicles, which move to seven tonnes and 11.5 tonnes respectively, with conditions, is welcomed.
Like so many other limitations, Euro 6 prime movers and trucks have been commonly available for more than 10 years. Whilst these steer axle mass issues are now being addressed, many operators have had Euro 6 complying vehicles for several years, some on their third rotation of Euro 6 prime movers, and suffered the tare weight penalty with a corresponding reduction in payload – a productivity disbenefit.
Whilst the requirement for a minimum 315mm section width will be seen by some as a hurdle, at least the maximum width of 2.55 metres does provide some scope for retreads; 315mm section width in dual configurations can at least be used on these prime movers.
Some road trains are permitted up to 7.1 tonnes steer axle mass, but these are required to have a minimum tyre section width of 375 mm and there is little scope for secondary retread use. The current selection of steer tyres with a section width ≥ 375 mm is limited.
The issue going forward now is what is next in the steer axle mass increase required to accommodate electric, hybrid and other low/zero emission technology in heavy prime movers? There has been some discussion regarding a need for 7.5 tonnes and beyond being necessary on single steer axle for some zero emission prime movers.
Whilst some electric vehicles currently enjoy a mass concession at both the steer and rear axle groups, these are limited to restricted routes. These concessions are not available to other vehicles; what conditions including minimum steer axle tyre section width are being applied to these vehicles?
The debate regarding higher mass limits for wide based single tyres (super singles) has been in discussion for several decades.
Recent research suggests that the pavement impact of super single is not as bad as road managers have promoted, something that industry has questioned all along.
Then there is the known improved fuel efficiency that super singles provide and the benefits in lowering carbon footprint. I doubt even the most adventurous gambler would be prepared to place bets on the timeframe for this recent finding to be introduced to legislation.
There are multiple issues with infrastructure managers, but they don’t own the infrastructure, the taxpayers own it. The infrastructure managers are there to manage, but by the state of the roads they are not doing such a good job.
It’s been more than 30 years waiting for an outcome on HML for super singles – better not proceed too hastily!
There will be alternative technologies to electric in the zero emissions race in the future and therefore concessions must not be limited by vehicle type but should be available to all vehicles that meet a publicly specified performance criteria, for example zero emissions.
If its reasonably known now that electric vehicles may require a steer axle mass of 7.5 tonnes and beyond, then preparation better start now.
The bridge or culvert or pavement won’t know if it’s electric, hydrogen or bio diesel powered, so the bureaucrats need to listen today and then get on with the task of informing the politicians of what needs to be done so they can introduce pass policy and have the bureaucrats get on with the task of being technology ready – before the technology gets here.
