Forecast-based gritting: from forecast to route and spreader

Falköping states that the function has been developed exclusively for, and is available together with, its own control system and Panel PC. Swedish trials have shown that the spreader can be controlled with control files, but according to a VTI report from 2021, the forecasts were not yet good enough for users to trust an automatic salt amount based on the forecast.

The chain from forecast to spreader

In the Swedish research project “Prognosstyrd dynamisk vinterväghållning”, the chain was described as follows, according to VTI resultat 2021:4. The link from forecast to salt amount in the control file was not completed, so the duty officer set the base amount themselves (see below):

• The forecast suppliers produce road weather forecasts in their decision support systems. In the project, these were Vaisala, Klimator and SMHI
• The control files are created from historical, recorded runs and contain, among other things, spreading width, position on the disc, coordinates for when the setting is to change, and the road section. They can be edited from the office
• At call-out, the duty officer selects a control file and enters the base amount. The system distributes width and amount along the route according to how the amount varied in the recorded run
• When the driver accepts the call-out and starts the app in the vehicle, the route and control file are downloaded automatically
• The spreader is connected to a box in the vehicle (BM SmartBox) with two-way communication. A tablet with the BM Combo app provides voice and map navigation and reports back how much salt has been spread

Tested, but the forecast part was postponed

The solution was approved in an acceptance test with one vehicle in Enköping in April 2020. The next step was to link the salt amount proposed by the forecast supplier to each road link in the control file. The evaluations showed that the forecast quality was not good enough for users to trust an automatic salt amount, and for the time being the users wanted the duty officer to decide the amounts. The project group chose to hold off on developing forecast-controlled salt amounts, because this could not be completed in the remaining project time.

What Falköping says

On its own page about the control system (friggeraker.se), Falköping writes that forecast-controlled spreading combines weather forecasts, real-time data and GPS control, and that automatic route control, needs-based spreading and full documentation provide decision support for both the driver and operations management. The category page for forecast-controlled spreading mentions, among other things, automatic adjustment of the spreading rate, digital reporting and integration with existing fleet management.

Falköping has been involved in the research. The manufacturer, Friggeråkers Verkstäder, carried out the pre-study for the automatic salt spreading together with BM System, and according to the project description on Vinnova's website, written by the project participants themselves, the two developed the handling of control files for salt spreaders. As early as 2018, the project described a collaboration with Friggeråkers on GPS-controlled spreading width based on historical data and automatic salt amounts from a decision support system.

Klimator, Vaisala and BM System

Klimator groups its products under the Saltera brand, and writes that compatible spreaders fetch the set points directly from RSI (Road Status Information) and use them automatically. On a campaign page, Saltera writes that larger spreader manufacturers such as Aebi Schmidt, Epoke and Falköping can be integrated. On the product page for the forecast-controlled solution, only Epoke is listed as ready to use, with a note that additional spreaders can be integrated on request. Falköping/Friggeråkers is listed as a partner for the road-condition-controlled solution, which is in a test and evaluation phase. More in Klimator and Saltera and the Ahead camera.

Vaisala writes that the MD30 mobile sensor can be built into systems for dynamic spreader control, which determine the spreading amount for each location based on real-time data from the MD30. The MDSS decision support system, which Svevia chose for its entire organisation, is set up to suggest routes and actions. More in Vaisala.

In 2023, Mesta started using Road Service System from BM System. According to TU, all Mesta's vehicles are getting screens with navigation support for optimised routes, and the winter maintenance is based on hyperlocal road weather forecasts, among other things. In Mesta's installation guide for the BM system, the check screen for spreader data shows data from a Falköping spreader. More in BM System and Smartbox.

The final report for phase 5 (2023) states that Svevia had held a first meeting with Vaisala, BM System and Friggeråkers about testing automated salt spreaders in Enköping in the winter of 2023/24. Vaisala was considered able to send a forecast amount via BM, which would add the spreading width from historical runs, to a connected Falköping spreader. A similar arrangement was planned with Mesta and Klimator in Norway. We have not found any report on whether the test was carried out, or how it went.

What research says about the effect

On the GPS-controlled part, VTI concludes that the salt can be distributed correctly across the carriageway without depending on the individual driver's skill, and that salt consumption falls because less salt ends up off the road. The figure the report cites, an average of around 8–10 per cent less salt, comes from spreader manufacturers and was not measured by VTI.

For forecast control itself, the picture is less certain. VTI writes that it is critical not to make the wrong decision, manually or automatically, as a result of the forecasts or the data behind them being wrong, and sums up that the opportunities are great, but that the challenges are also relatively great. The project participants still believe that winter maintenance costs can fall by 15–25 per cent with full implementation of the whole concept, in which high-resolution forecasts, automatic route optimisation and automatic salt spreading work together, but according to the final report from 2023, the pilot area came nowhere near this, probably because the sensor data requested was not available. The project estimates that 35 per cent of preventive salting operations are suitable for dynamic route optimisation.

The forecast is one of several inputs

Statens vegvesen (the Norwegian Public Roads Administration) states that it assesses the need for salting on the basis of observations from weather stations, inspections and weather forecasts, combined with local knowledge and past experience.

What you should clarify

Before you go ahead with forecast control:

• Which forecast service or decision support you use, and whether it can supply control files or amounts per road section
• Which fleet and data capture system the vehicles have, and whether it can exchange data with the spreader
• Whether the spreader has a Panel PC with GPS control and data collection
• Who sets the base amount at call-out, and who can override it

Ask us

Feel free to ask us about Falköping's control systems and data collection. You arrange the forecast service and the fleet system with their suppliers. How the GPS control itself works is explained in GPS-controlled gritting.