Enforced speed limits will bathe our roads in blood
Enforced speed limits will bathe our roads in blood
Amidst the noise and chaos of the spate of deadly heavy goods vehicle accidents we are experiencing – especially those involving coal side tipper interlinks – JIM WARD suspects that the far-reaching effects of a menacing piece of legislation have been largely overlooked.
On 11 November 2016, goods vehicles with a GVM or GCM above
9 000 kg were restricted legally to a maximum speed of 80 km/h. These speed restrictions were implemented immediately, with no grace period attached. Draconian fines were threatened against any dealers selling “open” (ungoverned) trucks. This legislation was easily enforced in the law-abiding environment of truck dealerships and manufacturers, all of whom need to remain legally compliant.
Since that enactment, all new trucks with a GVM over 9 000 kg have to be sold with their speed limit set to a maximum of 80 km/h. Local authorities have a statutory duty, under Section 39 of the 1988 Road Traffic Act – 8 “to take steps to both reduce and prevent accidents”. The Road Traffic Inspectorate (RTI) is responsible for ensuring compliance with the National Road Traffic Act. This Act really represents a massive indictment against Road Traffic Management and its policing, and highlights a lack of understanding of the operating norms and nuances of South Africa’s road transport industry. The logic behind it was rudimentary – a naive belief that forcing all trucks to go at the same speed would somehow reduce accidents.
This legislation was one of the clearest, unequivocal acknowledgements that road users continue to demonstrate a national reluctance to comply with speed limits and, equally, that the police/RTI feel unable to enforce them, or even basic traffic regulations. It highlights a deep misalignment between the thinking of the Transport Ministry and the transport industry, but dealers and manufacturers alike are stuck with it. Rather than address these various shortcomings, the authorities instead attacked an easier target, imposing an unpopular decision and burden on dealers. It was a kneejerk reaction that has failed to achieve its aims. It has instead had precisely the opposite effect, with notable increases in heavy goods vehicle (HGV) accidents, fatal head-on collisions, overtaking accidents, and front and rear collisions.
While I can accept that accidents often have multiple causes, this sledgehammer act is ill-conceived, ill-judged, and poorly considered, and increases the pressure already faced by a highly competitive and weakly regulated transport industry. It has added to the numerous burdens of recent times, and has in fact worsened overall road safety, as opposed to improving it. Unless, that is, you believe in absolute fatalism – that all accidents are inevitable, and all that one can do is reduce the speed involved when vehicles hit each other.
Unfortunately, that is an overly simplistic approach to a complex issue and there are serious flaws in this thinking. The crux of the problem lies in the extended time a truck will now spend on the “wrong side” of a two-lane road when overtaking. It is generally accepted that the most dangerous time spent on a road is when you are travelling on the wrong side of it – in the lane occupied by oncoming traffic – to overtake. A car driver mitigates this risk by reducing those vulnerable seconds spent on the “wrong” side of the road to the absolute shortest time. They accelerate to pass the vehicle being overtaken and complete the overtaking manoeuvre as quickly as possible.
Achieving this in a car is straightforward. You just drive much more quickly than the vehicle you are overtaking for a short time. You drive past them because you can move faster. It really is that simple. Anyone who has ever been passed by a powerful motorcycle that overtakes them closely at a speed in excess of double the national limit, will appreciate the significance of speed differential and speed variance as I explain them.
Technological progress in road transport is relentless. If this legislation had been passed 40 years ago, when most engines were still governed by mechanical governors, setting such a speed limit would have been a hit-and-miss affair. But those days are long gone. Modern commercial vehicles – especially in the > 9 000 kg range – must be highly efficient. They are likely to have electronic fuel injection and their engines, transmissions, and even braking predominance and air suspension will all be managed by advanced electronics.
Today, central processing units (CPUs) or engine control units (ECUs) have powerful processing capacity and are exceptionally accurate. If you were to line up any six modern 6×4 trucks, each capable of hauling either a semi or interlink and operating up to 56 tonnes GCM, and have their respective dealers set their engine control units to allow a maximum speed of 80 km/h, the maximum speed variance between these six trucks is likely to be as little as 0.2 to 0.4 km/h – essentially, next to nothing. They are all only able to achieve an almost identical maximum speed.
So under these conditions, let’s assume one driver decides to pass another, using his tiny speed variance of 0.4 km/h. The overtaking combination is
22 m long, but it requires a further 4 m to pull out and clear the back end of the “overtakee”, and another 4 m after passing the front, to ensure that the trailer tailboard clears the cab of the truck behind. The driver must therefore cover 26 m, travelling faster than the other vehicle, just to draw his cab alongside the other truck. But he also needs to pull his entire 26-wheel combination safely past the truck being overtaken, and the rearmost part of his trailer must clear the “overtake”.
That means a 30 m safe overtaking distance, plus 22 m to get fully clear of the truck being overtaken. This is 52 m spent in the overtaking lane, or on the wrong side of the two-lane district road. Thanks to this extraordinary piece of legislation, the faster truck can only travel 0.4 km/h (or 400 m/h) faster than the vehicle being overtaken. That works out to just 0.111 metres per second (m/s). It is slow. Slower than a slow walk; slower, even, than an old tortoise with arthritis.
The overtaking truck in this example must now cover 52 m at 0.111 m/s. That will take about 468 seconds, or almost eight minutes. Eight minutes of maximum exposure, during which time the dotted white lines may change to double solid white, a level road may become an incline, and an empty road ahead can easily become a busy one.
Even if the speed variance was unrealistically high for some reason, say 3% of the maximum permissible speed setting, such that one vehicle was capable of 82.4 km/h against another capable of 80 km/h, the minimal variance in speed remains hugely problematic. The 2.4 km/h variance
(2 400 m/h) equates to 0.66 m/s. The faster (illegal) truck would still need 79 seconds to pass the slower one. It will get worse if the driver being overtaken finds a few more rpm if the cooling fan disengages or they turn off the A/C to gain some more speed. When you watch one tipper passing another – taking two or three minutes to do so – this is what you are witnessing.
The problem is that although the overtaking manoeuvre might have begun safely, over a minute ago, the two trucks are both covering 22.2 to
22.8 m/s. An overtaking period of 1.3 minutes means they have travelled 1.78 km from where they started. By this time, the wide chrome grille of that Freightliner heading towards you on the wrong side of the road is beginning to look very large indeed, and the Actros sleeper alongside it means there is nowhere to go…
In their respective cabs, one of these drivers must either hold his nerve and complete his overtake in the face of oncoming traffic (forcibly creating a third lane, as they often do) or the overtaken truck must back off, drop speed, and let his vehicle be passed. We see this every day of the week. If you wonder why trucks take so long to pass each other, this is why. The decision to overtake can be blamed on the driver, but how long it takes him is no longer his fault.
If they cannot pass each other on level ground because their respective speeds are so closely matched, the only other option is passing on an incline. Here, a higher horsepower vehicle will normally have a slight edge, being better able to maintain 80 km/h – even on an uphill. But the speed variance may still be fractional. If the vehicles coming towards them are travelling downhill they are likely to be travelling faster than 80 km/h, even if they are exceeding electronically governed speed limits.
So we return to that white knuckle, three or four-minute pass, with a more powerful truck forging uphill just a fraction faster than its slightly lower horsepower cousin. Neither driver will give an inch. One might gear down, increase engine rpm and close the speed gap, but they sit side by side, occupying both left- and right-hand sides of the road. Any motorist will have witnessed this.
What might happen next?
A coach, its driver just easing off as he breasts the brow of the hill at
95 km/h, suddenly encounters two interlinks, side by side, both coming uphill towards him using all of a two-lane road. Closing speed is now about 49 m/s, (175 km/h), but neither the coach nor the links can change direction without falling off the tarmac. The R3 million coach cannot stop in time and the two links – with inertia gained before the hill – are carrying enormous momentum: 2 x 56 tonnes at almost 80 km/h.
When this happens, you will certainly hear about it on the news later that day.
Drivers frequently have their driving habits tracked remotely, and desired habits are often incentivised. Operators (and manufacturers) can easily track aspects such as fuel consumption, total percentage of drive time in top gear, use of retarder, brake applications/km, and how often an exhaust brake is applied. A driver who can increase his earnings by using his retarder rather than applying brakes, meeting a fuel consumption target, or meeting loading and offloading time slots because of the pervasive pay-per-load practice, will be very reluctant to jeopardise any of his targets.
Drivers have also learnt by now how to slipstream, because they all drive at the same speed. Tucking in behind another truck, with only a metre or two between the rear trailer and the front of your cab, means you can back off, use significantly less fuel, and glide along in the hole in the air kindly made by the leading truck. But you cannot pass, because both trucks can only travel at 80 km/h, so before long this results in a long train of combinations, all travelling within a few metres of each other and all travelling at 80 km/h. Do you really believe that this will help to reduce and prevent accidents?
Now, if a motorist pulls out to overtake, they may not realise they are actually attempting to pass “a vehicle” that is effectively over 100 m long. Because there is no speed variance permitted thanks to this punitive legislation, the line of trucks may stay glued together like this for hours on end.
None of them can pass five or six trucks in a line unless they have been “opened” (speed control removed). So they thunder across the landscape as one, inattentive and relaxed behind their cruise control, with only the leading driver able to see what lies ahead. If that truck suddenly emergency brakes for a taxi, stopping dead in the road without warning, and that vehicle has all the bells and whistles – ABS, EBS, ESS, emergency brake assist, and disc brakes – fitted on every axle, it will probably out-brake the vehicle behind, which will in turn either crash into the trailer tailboard, or swerve to miss it, straight into oncoming traffic. The recent fatal accident in Richards Bay – where one truck sequentially ploughed into another in quick succession – is a prime example of this.
The effect of this enforced speed limit is that trucks of similar mass, limited to precisely the same speed, will invariably bunch up on the open road, either to save fuel or simply because they cannot easily overtake. The truck in front is not necessarily faster, it just happens to be the one that started first.
Traffic behaves like a living organism. Left in its natural state, faster moving vehicles will tend to move clear of slower ones. Well, that used to be what happened. Operators strictly enforced the 80 km/h speed limit and drivers knew this, but operators understood that there would be moments when a vehicle might travel at 84 km/h or so, to pass something slower. It was deemed preferable to get that inevitable process over as quickly as possible, not prolong it in the danger zone.
In 2023, however, it makes no difference whether your truck has 430 or 600 hp. If your vehicle is limited to 80 km/h, you will end up bunched up on a level road – unable to overtake by law and unwilling to slow down, as it would mean losing your place in an exceedingly long line and forsaking an incentive bonus by missing an offload slot.
| Time required to pass a 22 m long combination travelling at 80 km/h | ||||||
| Vehicle type | Speed during overtake (km/h) | Speed differential (km/h) | Speed difference (m/s) | Passing time over 30 m (22 m + clearance) | Passing time over 55 m (two links + front & rear clearances + 3 m gap) | Comment |
| New truck ex dealer | 80.1 | 0.1 | 0.028 | 18 min | Impossible | Cannot safely pass |
| Truck | 80.4 | 0.4 | 0.11 | 4 min 30 secs | 8 min 15 secs | Cannot safely pass |
| Truck | 80.6 | 0.6 | 0.17 | 3 min | 5 min 30 secs | May try to pass anyway |
| Older truck | 84 | 4 | 1.11 | 27 secs | 49.5 secs | Can overtake |
| Private car | 120 | 40 | 11.11 | 2.7 secs | 4.95 secs | Overtakes safely |
| Suzuki Hayabusa 1300 | 215 | 135 | 37.50 | 0.8 secs | 1.46 secs | What trucks? |
Consider a situation where one 500-hp interlink combination wants to pass a 460-hp vehicle with the same trailer combination and load. On a flat road, these trucks will gradually draw closer and closer to each other, both running as fast as they are able to, but unable to overtake. Perhaps other combinations will join them. You now have what is effectively a train of heavy goods vehicles, each perilously close together, all running at a constant 80 km/h.
One only needs to visit a town such as Ermelo and witness side tipper coal combinations rumbling through small streets at eight second intervals to begin to sense the impact of this legislation.
If a new car buyer was informed at handover that it had been limited to 120 km/h by the dealership to prevent them ever exceeding the maximum national speed limit, they would be outraged, and the immediate question would be asked: what about overtaking?
What the Minister has set in place is an incredibly dangerous scenario. It lengthens the period trucks and trailers spend in their most exposed and hazardous situations, and creates bunching – a menace that in turn endangers other road users. It is a badly thought-out piece of legislation that disregards satellite tracking and the technology in modern trucks, and it urgently needs reviewing. Instead of preventing accidents, it is creating the exact conditions that cause them.
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focusmagsa
If the truck in front of mine is running at or close to the maximum speed of 80 km/h, would it be necessary for me to overtake? If the truck in front is running at relatively low speeds at say 40 – 60 km/p would this not give the overtaker the advantage of speeding up and successfully overtaking within a short space of time.