Max Bögl and Bomag conduct practical tests of the BW 174 Hybrid and BOMAP

By the planned end of construction in 2021, a total of 300,000 sq m of asphalt will have been paved at the Fürth/Erlangen interchange. Of this, 2.4km is porous asphalt on the A3, and 2.3km is low-noise stone mastic asphalt on the A73. For this construction project too, one of the largest traffic projects in Germany, Max Bögl is using compaction technology from Bomag.

Optimised traffic management with flyover and underpass

The construction site at the Fürth/Erlangen interchange is part of the six-lane expansion project of the A3 between the motorway junction Biebelried near Würzburg and Fürth/Erlangen.

The flyovers from the A3 onto the A73 from the direction of both Würzburg and Nuremberg will each be widened to two lanes to ensure a significantly better flow of traffic, particularly at peak times. For this, the classic cloverleaf design will be replaced with two new constructions: the flyover and the underpass.

After completion, traffic from Erlangen to Regensburg will be routed smoothly via the flyover without any merging or roundabouts. The dual-lane flyover will already begin at Bruck on the right, where it will then pass over the A3 in an elegant left curve to then enter an underpass under the A73 before both lanes merge into the many lanes heading towards Tennenlohe.

Practical test during ongoing construction operations

To further increase its own quality standards and efficiency while at the same time conserving resources, Max Bögl is testing two innovations that Bomag presented at this year’s bauma trade fair.

The pivot-steered BW 174 AP AM Hybrid tandem roller is one of Bomag’s answers to requirements to reduce energy consumption and emissions on the one hand and to increase performance and efficiency on the other. The oldest tandem roller in use in this infrastructure project is the 174 AP AM, built-in 2007. This split-drum tandem roller is already equipped with the tried and tested ASPHALT MANAGER, which offers the selection of three exciter systems including oscillation.

Roller test under real conditions, BW 174 AP Hybrid

Bomag’s hybrid drive concept makes their machines quieter and more economical, and therefore more eco-friendly. In addition, the integrated hydraulic hybrid accumulator offers dynamically retrievable power storage to provide top performance on demand. It has the capacity to generate up to 100 Nm and 20 kW of additional power, which corresponds to a total output of 75 kW and thus the level of its conventional sister rollers. In push mode, the hydraulic accumulator is recharged without the use of external energy.

Tandem rollers compared under real conditions

The roller quartet consists of the tandem rollers BW 174 AP-4 AM, BW 174 AP AM, BW 154 ACP-4 AM and the BW 174 AP AM hybrid tandem roller. The hybrid roller has the same system performance as the conventional tandem rollers of the BW 174 series. However, the 75kW is divided into the 55kW diesel engine and the 20 kW hybrid accumulator. This reduces the fuel consumption of the hybrid model by about 20 per cent, and the CO2 values drop accordingly.

This is made possible by the integrated diesel engine which meets the limit values of emissions standard V. The combination of the particulate filter, oxidation catalyst and a cooled exhaust gas recirculation system enables the BW 174 AP Hybrid to run without additives such as AdBlue. In addition, the roller drivers experience the hybrid model as considerably quieter and thus more pleasant when rolling.

BOMAP ─ a helper for the roller driver

BOMAP was developed by the compaction specialist Bomag for roller drivers to support them in their responsible task in a practical and easy manner. This free app can be installed like any other app on mobile Android devices. The menu is intuitive and easy to understand just like most other apps, and who doesn’t use such useful “helpers” on their tablet PC or smartphone these days? The self-explanatory, mobile solution shows the roller operator the precise compaction pass being performed while driving in real-time on the screen.

This shows the driver areas that have already been compacted or still need to be compacted, and the roller's position on the road section, thus, ensuring that no pass too many or too few is performed. The roller drivers are better able to manage their paving and working times, and the site's time management is supported effectively. In addition, less fuel is required, machine wear is reduced, and the work result is optimised. When the tablet with BOMAP installed is powered up, BOMAP connects to the machine interface and registers the machine parameters. The roller driver only has to add the required compaction passes and can then start directly. In other words, everything is just like the navigation systems that almost every motorist uses today.

Reality test under everyday conditions passed with flying colours

In the night from 14 to 15 July 2019, the field test was performed under completely normal paving conditions. Around 3,000 t of base course was installed in this night shift and compacted with the four tandem rollers. During the initial hours of testing – the measuring results were constantly monitored by the site manager and Max Bögl material planners, as well as the Bomag product manager and regional sales manager – there was a significant deviation in the tandem rollers’ position location. The hybrid roller with an external GPS receiver was displayed with an accuracy of approx. 15 cm. The position determination via the GPS receiver in the tablet PC resulted in deviations of between two and three metres, thus providing only a rough orientation.

From the outset, the four roller drivers had no problems starting BOMAP, connecting it to the machine interface and adding the few parameters manually. The visualisation of the work results in combination with the current roller position greatly helped the drivers in the long night shift because the “normal” visual orientation at night on the “black tarmac” is very exhausting and imprecise.