One of the steepest sections of the B 500, an important road in the southern Black Forest, had to be renewed in the summer of 2023 – more precisely: the first kilometres behind the Triberg town sign, past the famous waterfalls. Asphalt paving specialists from Gebrüder Bantle GmbH & Co. KG were commissioned to resurface the carriageway.
For the pre-planning of the paving operation and to ensure the smoothest possible paving logistics during the crucial summer week, Bantle's site management team used the newly developed BOMAG ASPHALT PRO software for the first time. They also relied on BOMAP, and three of the four BOMAG tandem rollers deployed were equipped with ASPHALT MANAGER. The objective: to achieve the best compaction results as quickly and efficiently as possible!
If you have ever marvelled at Germany's highest waterfalls outside the Alps and driven along the B 500 federal road from the south, you will surely remember the descent into the Triberg valley: The last few kilometres are really something. The average gradient here is 7.4 per cent, with three narrow hairpin bends to negotiate. Escape lanes? Negative! The slope on both sides of the roadway is extremely steep.
In the summer of 2023, this section of the B 500 was closed. Freiburg’s Regional Council ordered the renewal of the asphalt, which had been heavily stressed by traffic and weather, over a total length of 2.7 kilometres. In the course of the reconstruction, the retaining walls were also raised, and the crash barriers and drainage channels were replaced. The asphalt paving was carried out by the Bösingen-based family business Gebrüder Bantle GmbH & Co. KG.
Some 130 construction specialists and engineers at Bantle plan and implement a wide variety of civil engineering and road construction projects – from the new construction and renovation of district, state and federal roads to the development of residential and industrial areas. The company also owns a stake in the AWZ asphalt mixing plant in Zimmern ob Rottweil.
The challenge in Triberg was particularly defined by the profile and location of the construction site. And: by the fact that, according to the plan, the entire asphalt construction operation – base layer, binder course and top layer – was to be completed within one working week.
In the past, Bantle's construction managers determined the number of lorries needed to deliver the mix using an Excel spreadsheet – in Triberg, this was done with BOMAG's ASPHALT PRO software. For the first day, the calculation showed: 21 vehicles were needed.
ASPHALT PRO allows for more detailed and precise planning compared to an Excel file. The software scores with its intuitive user interface and logically structured input screens. The construction site can be digitally represented in the shortest possible time. The clear visualisations in ASPHALT PRO greatly simplify the planning process for the upcoming road construction project.
But ASPHALT PRO can also monitor and control the ongoing paving process. The software continuously calculates further mix requirements and communicates with everyone involved in the project: the construction manager, mixing supervisor, drivers – all have an overview of the current construction progress and the further process at all times.
ASPHALT PRO not only enables seamless traceability of the paved material but also of the mix temperature – from production to the fully compacted asphalt. The smart assistance program can be accessed from anywhere: an Internet connection is all that is needed.
In addition, ASPHALT PRO immediately communicates delays or changes to the plan. The benefit for the mixing supervisor: they know exactly when the next empty truck will return and the total tonnage that still needs to be mixed. The benefit for the construction manager: they can always see how much material has already been paved, how much mix is still in transit, and what still needs to be paved. In addition, a target/actual comparison indicates whether the thickness of the layer paved so far is correct.
Without any information from the construction site and no more trucks arriving, it can happen that I mix 200 tons too much. That's the worst-case scenario.
Monday morning: 1,500 tons of bearing course are to be paved on the first day. The shift at the mixing plant starts at 4 a.m. The first load goes out at 5.30 a.m. The asphalt temperature leaving the mixing plant is 160 °C to 180 °C. The base course installation starts at 6.30 a.m. - here as profile levelling and 8 to 14 cm thick. 21 vehicles are in circulation. A total of 63 trips are planned.
Monday noon: Shortly before midday, a lorry breaks down with a flat tyre right on the construction site. The mixing plant is informed via ASPHALT PRO. No one needs to reach for the phone any more. The software recalculates the mix transport and the actual circulation times, taking into account the remaining quantity of mix required. The scheduling is adjusted. The truck drivers also receive all important information via the ASPHALT PRO app.
Monday afternoon: made it! The paving crew has almost reached the top of the pass. The daily target is met at 3.30 p.m. The quantities paved, journey times and delivery note data are stored in the cloud. ASPHALT PRO has documented the disruption in the process. All the data will form a sound basis for efficient paving logistics over the coming days. Paving of the binder course can begin the next morning.
The asphalt grade AC 16 BS SG used here is a very common paving material in the Black Forest. And for good reason: a large number of heavy, slow-moving trucks navigate the B 500 every day and have to overcome many metres of altitude. In addition, very small radii often have to be negotiated on the winding route.
This type of asphalt is ideally suited for such heavily used, high-altitude traffic areas because AC 16 BS SG is characterised by a high degree of cold flexibility. After all, the average annual temperature in Triberg is only 7.8 °C, which is 2.5 °C lower than at the foot of the Black Forest in Freiburg.
But the paving material is also a good choice for the B 500 thanks to its high resistance to deformation. High shear forces occur in the tight bends and winding roads. Accordingly, polymer-modified bitumen 25/55-55 was used as a binder. This bitumen stands out for its excellent adhesion to the aggregate and particularly high cohesion, thanks to the elastoviscous behaviour of the polymers already mixed in at the factory.
Four BOMAG rollers were used in Triberg to ensure the optimum compaction of the paving material: the BW 174 AP-4 AM and BW 174 AP-5 AM models, the pivot-steered BW 154 ACP combination roller, and the BW 206 AD-5 AM, an articulated asphalt roller. Three machines were equipped with the ASPHALT MANAGER (AM) assistance system, only available from BOMAG.
The rollers with ASPHALT MANAGER can work even more efficiently in road construction and significantly more gently than conventional systems. The Bantle drivers only needed to select the layer to be compacted, and the roller took care of the rest. ASPHALT MANAGER automatically adapts the amplitude to the compaction already achieved.
This avoids jumping - over-compaction that can lead to aggregate crushing. Thanks to the integrated measurement of the EVIB value in ASPHALT MANAGER rollers, the drivers were always informed about the current compaction progress.
The roller drivers used BOMAP to avoid unnecessary passes. An additional tablet PC with the BOMAP app pre-installed was mounted in each driver’s cab.
BOMAP makes it a breeze to check and document the compaction status. Differently coloured areas on the tablet PC screen show the number of passes already completed, providing feedback on the current compaction progress: If the area is red or green, further compaction is required. If the area is blue, the number of passes required has been achieved.
No expensive special hardware needs to be purchased for BOMAP. The app runs smoothly on modern tablet PCs or Android smartphones. The app uses the mobile device's internal GPS to determine the position. If a wireless GPS antenna is used, the map display and documentation of the compaction process can be shown in even more detail.
Only a short briefing was necessary in Triberg. The roller drivers immediately understood the self-explanatory app. They no longer needed to make any complicated settings. BOMAP was ready for use right from the start of construction.
Thanks to BOMAP, it was clear to every Bantle roller driver at all times where the freshly paved material had already been optimally compacted or whether further passes were required. The app is the perfect navigation system. The risk of over-compaction by a following roller can be reduced to a minimum with BOMAP. And just as important: drivers can directly steer to areas that have not yet been sufficiently compacted.
With BOMAP Connect, data from the four machines operating on the site was combined, and the results were output to the tablet PCs mounted in every roller within seconds. This included information on vibration status and asphalt temperature - via the Joblink interface for surface covering compaction control.
An older pneumatic tyred roller from another manufacturer was also intended for use on the construction site. The roller was equipped in advance with the BOMAP SENSOR KIT in a few simple steps. Magnetic mounts made the process quick and easy.
Now, even the “alien” roller was able to record the surface temperature in BOMAG quality and contribute the measured values for transparent and comprehensive documentation.
The complete BOMAP SENSOR KIT includes a temperature sensor, a vibration sensor, the JOBLINK interface, and cables and mounts − everything needed to upgrade a machine to the latest BOMAG technology at low cost.
For us, this was the first deployment of BOMAP and ASPHALT PRO. Our conclusion: Quick and easy to install. Self-explanatory and easy to operate. And best of all: We have the overview in every situation!