Smart road construction in the widest tunnel in Switzerland

It is one of the most complex infrastructure projects in Switzerland: 2022 sees the opening of the third bore of the Gubrist tunnel, 3.2 km long, as part of Zurich's northern by-pass. With a diameter of 16 m, it is the largest tunnel bore in the country and is intended to relieve the chronic congestion of this section of road by providing three extra carriageways towards St. Gallen/Bern. The demands on the road construction process were correspondingly high: despite the complex tunnel logistics, parallel working and heavy traffic, approximately 20,000 t asphalt had to be paved within a tight schedule and meet stringent quality standards. This was why contractor Marti AG Solothurn Bauunternehmung decided to approach the project using a digital road construction solution. “As one of the largest contractors in Switzerland, the Marti Group has been active in driving digitalisation in all areas of construction for years - from structural to civil engineering. For a project of this scale, it was obvious that we should use a solution which enables us not only to visualise planning digitally, but also to control job site processes actively,” says Cedric Berrut, civil engineering operations manager.

Networked system solution from the paver manufacturer

VÖGELE’s WITOS Paving Plus product was the one selected. This software-based process optimisation solution networks all those involved in the project from the construction manager to the mixing plant manager to the paving supervisor and on to the paver operator and consists of a total of five modules: these allow job site planning, provision of mix, transport of mix, asphalt paving and subsequent process analysis to be managed by one single system in real time. Among other things, this facilitates just-in-time delivery to the site and continuous paving with no paver stoppages. The paving team can react specifically to disruptions to the process. “One advantage from our point of view is that as an integrated solution from the manufacturer of the machine, WITOS Paving Plus matches the paver perfectly,” adds Berrut. “This gives us immediate access to all the machine data.”

Intelligent process control and the latest machine technology

For the contractor, there was another new feature about the job site: at 11.5 m, this was the widest paving project without joints ever completed in Switzerland. As a consequence, Marti also added two more VÖGELE machines to its vehicle park: the MT 3000-2i Offset PowerFeeder and the SUPER 2100-3i Road Paver in combination with the SB 300 Fixed-Width Screed. Combined with the Highway Class paver, the second-largest screed from this manufacturer achieves pave widths of up to 13 m and was therefore ideal for paving this three-lane section without joints. Over a stretch of road totalling 3.2 km, an 8 cm-thick foundation, base and binder course and a 4 cm-thick surface course were to be paved in two sections. “So on the one hand, we had to use a powerful combination of machines (feeder, paver and screed) which delivers an absolutely even result even across a large width, whilst on the other hand relying on intelligent process control to guarantee the smoothest possible processes,” says Berrut.

WITOS Paving Plus simplifies logistics

Paving the Gubrist tunnel required planners, construction managers and the paving team to take account of a number of logistical challenges: the mixing plant for Marti AG Solothurn Bauunternehmung is in Walliswil bei Niederbipp, some 100 km away. In order to avoid jams on this busy stretch of road and to minimise delays due to parallel working in the tunnel, Marti decided to pave at night. VÖGELE’s process optimisation solution simplified the logistical coordination of this process: the planning and control module allows planners to record and monitor all the key parameters, the machines required, quantities of material and their scheduling. The system transmitted to the mixing plant the number of trucks calculated, then compared this number with the data at the plant and calculated from this the cycling of the trucks and their arrival times on site. “Planning and production of mix were much more accurate,” reports Berrut. “This enabled us to match paving and compaction processes perfectly to suit material deliveries.”

Continuous paving, better utilisation

The job site module gave paving supervisor, construction manager and paver operator a real-time overview of paving progress, laydown rate and mix delivery throughout the entire project. The tablet PC or paver operator’s console enabled them to detect deviations from the plan in terms of paving time, paving distance or mix quantities and react if necessary. “This enabled us to ensure continuous paving and thus the appropriate quality,” says Berrut. Evaluation in the analysis module furthermore resulted in a significant reduction in waiting times as a result of cycling, as well as in fewer mix trucks than on comparable job sites. “Ultimately, this means reduced material and transport costs, fewer emissions, better utilisation and at the same time, better quality.”

Practical system with great potential

Another benefit of WITOS Paving Plus: the system can be used even under difficult conditions such as those prevailing in the Gubrist tunnel. In order to ensure reliable data transmission, Marti used a GSM network which was routed into the tunnel by additional antennas. “The project showed that WITOS Paving Plus is a practical solution with great potential for us,” adds Berrut. “It integrates well in our digital infrastructure and provides data we can use for our BIM models. This is a key point which we are going to expand on in collaboration with VÖGELE.” In future, Marti intends using the system for all projects involving regional and national roads and relatively large projects.