Mercedes-Benz Actros

The future driving environment for the Australian trucker is likely to be considerably different to the one they are in today. New technology arrives every year to enhance safety and integrate truck systems further. Mercedes-Benz have built a prime mover to show off all of the safety aspects of their Actros range.

Prime Mover took the opportunity to take the truck for a test drive out of the Daimler headquarters in Melbourne. Driving through the heavy traffic of a typical afternoon in the Victorian capital gave the truck a chance to use the safety systems and make the journey both safer and less stressful.

These basic devices and designs are available from quite a few truck manufacturers, especially those designed and built in Europe. In terms of the technology, especially the electronics, the suppliers of the core systems work with many manufacturers. The difference, from the point of view of the customer, is the way in which they are packaged on the vehicle and integrated with the vehicle systems.

The safety features included in the truck can be divided into two groups. Firstly, there are safety-related items which are included in the design of every Actros. Secondly, there are number of optional safety items. When buying a new truck, these are often sold as a package of safety devices.

Climbing into the cabin of the truck, the driver comes across the first safety feature, something Mercedes-Benz calls 'cascading steps'. The individual step comes out about 20 mm further than the step directly above it, giving a safer entry and exit for the driver. Although not sophisticated, it is a small contribution to the safety outcome but only possible on some truck layouts.

The industry has achieved some real results in improved access to truck cabins in the past 20 years. Not only have the layouts of steps into trucks been improved but the surface on which the driver stands is also much less likely to cause a slip. Many of the innovations have been driven by the WHS concerns of operators who, as employers, need to demonstrate a duty of care to those driving trucks.

The next simple safety feature the driver comes across is the three point seatbelt. Although it is not standard across all of the new trucks on the market, a lap sash seatbelt integrated into the driver's seat is becoming the norm. Some manufacturers still fit the belt to the B-pillar but this is largely because the cabin design they are using was not intended for use with a driver seat fitted with an integrated seatbelt.

Another aspect of the seatbelt design starting to appear in many trucks, and is included in this Actros, is the pretensioning seatbelt. When the vehicle senses an accident is about to happen, the system automatically tightens up the seatbelt in order to secure the driver safely to their seat. This sensing system also activates the driver's airbag, another relatively new safety feature and fitted in this Actros, which is becoming more and more prevalent throughout the industry.

The driver's airbag, fitted in the steering wheel, can become a bone of contention between an operator who is trying to improve safety outcomes within their fleet and the more traditional truck driver who has a preference for a more traditional style of steering wheel. Out on the road, in the Actros, the style of the airbag steering wheel suits the modern European design of the Mercedes-Benz cabin but would look out of place in the more traditional North American style interior.

This Actros also has a couple of features which can't really be called safety items but which do make life a little simpler for the driver. The headlights are fitted with a light sensor and will automatically turn on when the light levels get low enough. Also, the windscreen wipers are automatically activated when the system senses rain on the windscreen. Both of these systems were developed for the Mercedes-Benz car market but offer an option to the truck buyer. While the automatic headlight option can be quite useful, especially when going in and out of the Burnley Tunnel, the automatic wipers find it difficult to judge the amount of rain and sometimes need manual intervention when conditions change.

The really significant safety features available as an option on the Actros and other modern trucks are the sophisticated safety intervention devices involving electronics and integration with the driveline. These are the systems we are going to be seeing more on trucks in the future and become more a part of the truck driver's life.

One of the new features, Active Brake Assist, is standard on the Actros. This relies on a radar set just above the front bumper which detect vehicles in front of the truck and will activate braking systems if the vehicle is slowing down quickly or if the truck is approaching a vehicle too fast. When first activated, the engine brake and retarder is used and then service brakes are applied if necessary.

Systems like this have been fitted on Mercedes-Benz trucks for some time and have been finely tuned enough to be practical. The radar appears to only pick up vehicles in the truck's way and not pick up other vehicles in different lanes. Overtaking vehicles that cut back in front of the truck do not activate the system as long as they are accelerating away. This aspect of the equipment's behaviour was repeatedly illustrated on the busy Monash Freeway.

When looking at the extra options involved in the safety package offered by Mercedes-Benz, an extension of the Active Brake Assist, Proximity Control, is included. This uses the same radar but with more sophisticated control systems involved. When used in conjunction with cruise control the distance between the truck and a vehicle in front can be set using a stalk on the steering column. Even if the cruise control is set at 100 km/h the truck will travel along at a set distance behind the vehicle in front at the speed of the traffic around it.

In practice, when travelling through Melbourne in the middle of the day it was possible to set the cruise control at 100 km/h and leave most of the slowing down on speeding up to this system. As the traffic slowed in an 80 km/h zone, so did the truck. As the traffic cleared the truck automatically came back up to speed. If there was a disadvantage, it was when car drivers would move across into the gap created by the Proximity Control causing the truck to slow to re-establish the gap. This can be annoying for the driver but it does maintain a safe travelling distance.

Another device fitted to the front of the truck inside the windscreen is the lane keeping control. This looks ahead of the truck and finds white lines or the boundary between the road and the verge. If the truck approaches the edge of the lane, the system automatically sets off a warning. This consists of a sound like a rumble strip coming from the appropriate speaker on the left or right side of the cabin.

The rumble strip noise is enough to wake any driver guilty of inattention. Several times, when manoeuvring in busy traffic, this driver was alerted to the truck wandering while the driver was paying attention to other traffic on the road. The system can become very annoying when the lanes are particularly narrow but on normal highway conditions it only intervenes when necessary. If the indicator is active or the driver is deliberately steering across the white line there is no alarm.

Also available in the safety package is the Voith retarder, which is also available in a number of other brands on the Australian market. This is a useful adjunct to the other systems in maintaining safe and effective retardation. As a smooth transmission brake activated in a braking sequence, between the exhaust brake and the service brake, this makes slowing down as smooth as speeding up.

The inclusion of a retarder is needed as the engine braking on this Mercedes-Benz engine is not particularly effective. By adding in the retarder, the Actros can replicate the kind of retardation available to trucks using engines with much more effective compression braking. When the next generation of Actros reach our shores they will be fitted with the new Daimler engine, the Mercedes-Benz version of the DD 13 and DD 15, which is fitted with a very effective compression brake system. However, in terms of safety, the substitution of a retarder for the engine brake gives us the same result.

Another small contributor to the overall safety outcome is the hill hold function on the ABS braking system. This automatically holds the brake on for an extra two seconds when the foot pedal is released in a situation like waiting at traffic lights. This gives the driver time to move their foot from the brake to the accelerator, and when it is depressed the hill hold function senses this and releases the brakes immediately. This stops dangerous rollbacks occurring as the truck sets off.

While not being a safety function but an economic one, the transmission will automatically neutralise itself if the truck is travelling at high speed on a slight downward grade. The driveline does not need power from the engine to maintain speed and by disengaging the transmission internal drag is reduced, allowing the truck to coast for longer at the required speed. Any intervention by the driver or an increase in grade to accelerate the truck, or even road speed slowing, immediately cancels the system and the transmission is re-engaged.

Driving this Actros, while evaluating all of the safety systems available, shows they can be effective if used properly and allowed to function. The temptation will always be for the driver to turn off any function that could interfere with their total control of the truck. It can be hard to relinquish that feel, but experimenting with the systems demonstrates their ability to react far quicker than any driver. Also, items like the proximity control mean the driver has one less thing to think about, freeing up valuable brain space to look out for other safety concerns.

It is simply a matter of learning to trust the systems, to make that leap of faith and believe the radar will pick up the slowing car in front of the truck and activate braking systems. Even with all the systems turned on and running it is still vital for the driver to remain alert and be ready to intervene at any point. It's not a matter of just setting and forgetting; it is more about using even more sophisticated tools to make life for the driver a little simpler and a little safer.

On the evidence of a day's drive in Melbourne traffic in this Mercedes-Benz Actros, there appears to be real gains to be had in utilising the latest sophisticated safety thinking. For the operator justifying the additional expense of a new safety system can be difficult, any improvement in safety outcomes may be difficult to assess and evaluate. However, evidence in Europe seems to suggest these kind of safety systems may not reduce the number of accidents but do reduce their severity and monetary cost.


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