No entry for overwide trucks

Tunnels are often a true work of wonder and indispensable for transport. The sophisticated technology inside the tunnel and also before and after it plays a significant role in this. When functioning properly, the technology protects lives. Every so often, overwide vehicles cause damage to the tunnel walls and the technical accessories mounted on them. The Austrian motorway company ASFINAG and the company SPIE Dürr Austria jointly contacted the specialists at EBE Solutions to develop a solution to effectively prevent this. The LiDAR sensors from SICK feature in that solution.

No one wants traffic jams – the traffic is supposed to flow. Traffic telematics solutions are used in many areas these days to ensure that this actually the case by detecting and controlling the traffic. The company EBE Solutions GmbH in Vienna has been developing and implementing these kinds of innovative solutions for over 20 years, including custom solutions for traffic and parking space management, traffic data collection & analysis, and traffic safety. "Minimizing hazards for road users" is an issue of constant concern, and a key area of focus is the monitoring of tunnels and the specific challenges associated with this.

Partial closure of the Ofenauer tunnel

Spie Dürr Austria was commissioned to update the entire tunnel and traffic technology on an approx. 13-kilometer section of the Tauern Autobahn (A10) from the interchange at Golling to the Werfen exit. To renovate the Ofenauer Tunnel, each of the tunnel tubes in turn had to be closed from the fall of 2023. For the duration of the works, the entire traffic was directed through a single tunnel tube only, which resulted in the tunnel being damaged on several occasions by overwide trucks. The maximum permissible width of 3.20 meters was ignored multiple times, in particular at night.

Alfred Paukerl, Managing Director of EBE Solutions: "This width restriction was there for a reason. Tunnels are usually significantly wider at the bottom, however the round shape of the tubes means the total clearance width-wise at the top is substantially reduced. The higher the tunnel, the narrower it becomes and therefore tight for trucks with a tall load."This is especially the case when another wide vehicle then approaches from the other direction. "While trying to keep as far right as possible, the signs for emergency exits or the LED displays for speed restrictions would sometimes be damaged or even torn off completely," reports Alfred Paukerl. To ensure this did not happen again the following year in the fully renovated part of the tunnel due to the construction site in the opposite direction tubes, ASFINAG and SPIE Dürr Austria jointly contacted the specialists at EBE Solutions.

Tailored measurement solution

The task was to fully automatically determine the width of vehicles in free-flowing traffic so overwide trucks can be removed from the traffic before the tunnel. Alfred Paukerl: "A similar thing is done with vehicle weight measurements, which can also occur in free-flowing traffic these days. The idea was to develop a comparable solution for width measurement. As we had already installed a traffic jam warning system on the Tauern Autobahn ahead of the construction site area, it made sense for ASFINAG to inquire with us about such a width measurement system. We couldn't offer them a ready-made solution, but we were happy to accept the challenge and got SICK on board as a sensor specialist."

EBE-Road – a business division of EBE Solutions – and the experts from SICK jointly developed several concept studies that were successfully presented to ASFINAG. EBE Solutions were subsequently commissioned to implement a suitable pilot project as part of the tunnel renovation works on the Tauern Autobahn (A10). The project – jointly established by Spie Dürr Austria and EBE Solutions – required a sophisticated solution for integration into the tunnel control technology that takes into consideration the autobahn operation requirements and all system safety-related aspects.

Three 2D LiDAR sensors on the sign gantry reliably detected vehicle widths at the construction site.

Three sensors keep everything in view

The new system was mounted on the existing sign gantry in the Villach direction of travel about one kilometer ahead of the Ofenauer tunnel. "In consultation with SICK, it was decided that three sensors would be required for detection across two lanes, which would "look down" onto the road from above to detect both sides of the vehicles," explains the managing director of EBE Solutions. Each of the three laser sensors cover an angle of 180 degrees. From the acquired data, a "point cloud" is created which a software program then converts into an image from which the outline of the vehicle can be recognized. This solution works not only for trucks but for all vehicles in general. The width of a vehicle is calculated based on the point cloud. If the system detects that a predefined width has been exceeded, this data is forwarded to the tunnel control system.

The "point cloud" is converted into an image from which the outline of the vehicle can be recognized.

Automatic processes

In the event of an alarm, precisely defined, automated processes are initiated. In addition to an alarm notification to the tunnel control center, a special traffic program is activated to prevent wide vehicles from entering the tunnel. Besides reducing the speed using variable speed limit signs, information panels, and the switching of traffic lights to red in the pre-portal area, the arriving traffic is informed on an LED display, in two languages and using symbols, why the traffic has been stopped.

Manual re-measurement

The responsible traffic manager at ASFINAG directs the truck to a parking spot nearby and manually measures the vehicle. "If the vehicle is actually too wide, the traffic manager informs the executive authority which issues an administrative fine. The truck is then directed away from the parking spot through an underpass and can head back the other way," says Paukerl. The people at EBE Solutions have also considered another scenario, however. To cater for snow clearing vehicles that are wider than the permissible width, they have installed an "override switch". When a snowplough approaches the tunnel, the tunnel control center manually deactivates the system for a certain period of time via an interface to the tunnel control technology, thereby allowing the snowplough to pass through without triggering the system. "All these actions are logged," explains the managing director of EBE Solutions. "We have designed the system in such a way that all measured vehicles are saved as a point cloud to allow statistical evaluations. No license plate details are recorded, however.“

Reliable LiDAR sensors

The 2D LiDAR sensors of type LMS511 installed in the system have a compact housing with an enclosure rating of IP 67 as well as an integrated heater. Thanks to their rugged design and low power consumption, they are suitable for harsh, demanding application environments. The LMS511 also offers fast signal processing, several inputs and outputs, and the ability to synchronize multiple sensors. The scope of delivery from SICK also includes software which is tailored to the sensors and allows various application-specific adjustments to be made. Pre-defined filters, for example, make it possible to detect and blank out fog, dust, rain or reflections from window panes. Another advantage of using laser technology is that it is impervious to interference from ambient light.

LiDAR sensors

High-performance 2D LiDAR sensor for accurate detection of far away objects

LMS5xx

Measurement in any weather

A wide variety of weather conditions were also taken into consideration in this project. In heavy rain, for example, it is possible for heavy vehicles to produce significant spray. It must nevertheless be ensured that only the dimensions of the vehicle itself, and not the spray as well, are recorded. "In consultation with SICK, we were able to restrict the relevant measuring range from the upper edge of the vehicle to 80 centimeters above the road," says Paukerl.

This does not affect the likelihood of damage in the tunnel because transported objects can only cause damage if they are located on top of the truck. The lower area of the tunnel is wider and there is hardly anything there that a vehicle could damage. An illustrative example: boats. While boats are being transported to Italy in the spring, it is a common occurrence for a truck and its load to be too high or too wide. As no approvals for special transports of this kind are granted for the duration of the construction works, these vehicles need to be diverted via another route.

False triggerings not allowed

Red traffic lights for no reason on the A10 were, of course, a no-no, so incorrect measurements were not allowed. The project was also the first of its kind in Austria. Particular attention was therefore paid to ensure the precise calibration of the sensors. The lane width was first measured, then a reference object positioned centrally below the sensors in order to individually adjust the X, Y and Z axes of each sensor. After the calibration phase, the system was activated in September 2024 and several triggerings immediately occurred – correctly as it turns out. The load on the truck was too wide. After two weeks, however, the number of alert notifications began to decline – apparently the word had gotten around in the transport industry that "laser eyes" were now carefully monitoring, day and night, the width of the vehicles ahead of the tunnel.