Curative salting in Barneveld requires highly accurate ice forecasts
In the municipality of Barneveld, winter road management is the responsibility of the Public Space Management Department. Although it consists of seven teams, winter road management is an activity that transcends the remit of the individual teams. The department employs approximately 120 field staff and approximately 30 office staff. The winter road management service has 10 salting trucks at its disposal and three tractors, if necessary. The municipality of Barneveld uses 'curative salting' and relies on the accurate forecasts of MeteoGroup.
Three road authorities operate in the municipality of Barneveld: The Directorate General for Public Works and Water Management (Rijkswaterstaat) salts motorways, the province of Gelderland salts provincial roads, while the municipality salts its own roads. Each road authority is responsible for its own salting policy and decides whether or not to initiating salting. In some cases, one road authority will salt roads for another road authority, in situations where it would be logical for salting routes to connect up.
If icy road conditions are expected, surface conditions in sensitive locations are measured and other road authorities are contacted. The municipality uses the ice measurement system and information provided by MeteoGroup.
Gerard van der Bij, Winter Road Management Coordinator for the municipality of Barneveld: “We started working with MeteoGroup about 10 to 12 years ago. A lot has changed since then, in the way that data in apps are presented, for example, but also in terms of the speed of information availability (virtually real-time) and the accuracy of forecasts and models.”
“MeteoGroup is the ideal supplier for us, because of its service-oriented approach, the possibility of in-depth consultations with the winter-maintenance meteorologist on duty and its straightforward registration procedures. The various measurement data and weather forecasts are presented in a way that is both practical and easy to understand.”
“MeteoGroup always warns us of icy road conditions two hours in advance, which is ideal. It calls us when it sees something heading our way that could impact our road conditions. The level of ice present can also vary from one place to another. For example, roads in Barneveld might not be icy yet, but the situation could be very different in the Garderen area, because the roads there are higher lying. The type of substrate, road surface and location in relation to buildings and trees also determine how quickly a road will become icy. With this in mind, the municipality is now introducing an additional measuring point (bringing the total to two measuring points), which will enable us to respond better to height differences in the municipality as well. The sensors also make it possible to see whether salting has been done and whether enough salt is still in place. This is important when liability claims are brought following an emergency situation too. The road authority always has ultimate responsibility.”
“We operate two types of salting route in Barneveld, because of the extensive road network. The need to make choices is unavoidable. Salting route 1 covers the most important roads, streets and cycle paths – which are through roads, local access roads, bus routes and through cycle-paths, etc. They can be salted at any time, including the night time hours. Approximately 370 km of roads and cycle paths are treated on salting route 1.”
Salting route 2 covers the other roads, streets, squares and cycle paths. However, this route is only operated during standard working hours, when the roads that form part of the salting route 1 have been salted sufficiently. As such, salting route 2 will NOT be covered on Sundays or public holidays, for example.”
Curative salting requires accurate ice forecasts
“Our municipality has opted for curative salting. This means that it only starts salting when road conditions are icy, or if it is virtually certain that road conditions are going to deteriorate”, Van der Bij continues. “This is different to preventive salting, which involves salting at an early stage. The combination of a liquid (brine) with road salt ensures that the salt spread sticks to the road surface. Then, when the road freezes, the salt already present stops the road from becoming icy. Curative salting involves the use of road salt. Because no liquid is added, the salt, which has a low level of adhesion, disappears from a dry road surface faster. This is why curative salting is only initiated when road surfaces are moist and icy or are set to deteriorate soon.”
“Our approach goes very much against the national trend. Today, 80% of road authorities have opted for preventive salting. The biggest advantage of this approach is timing: it's much easier to do salting in 'your own time'. In principle, preventive salting keeps driving speeds up too, but our road network doesn't lend itself for this; we wouldn’t stand to gain anything. In theory, fewer vehicles are necessary for preventive salting, but this wouldn't work for us.”
“The simple reason for us to choose curative over preventive is that preventive salting is regularly found to be premature. In Barneveld, we salt roads approximately 25% less than similar municipalities do. This substantially reduces the manpower we need and drives costs down too. It's better for the environment as well. However, more monitoring and surveillance are necessary to ensure that the same level of safety is achieved.”
“So, it's important for us to be able to respond faster. The extra monitoring and surveillance required are primarily the responsibility of our partners at MeteoGroup. We rely on them to have someone in the weather room to watch the weather at all times. Fortunately, they have never let us down. We know each other very well and are always alerted in plenty of time, whether via our direct line with the weather room or our online systems (gladheid.nl and the RoadMaster app). Given the reactive nature of our approach, we also make sure that our residents are aware of the need to stay alert in the event of icy road conditions too.”
“Because our salting policy can be different to the salting policy pursued by our partners and neighboring municipalities where the timing of salting is concerned, we always make sure that salting activities are stopped at logical locations (a junction or roundabout, for example). This can even mean extending salting activities beyond the municipal boundary.”
The drivers and shovel driver are alerted as soon as salting becomes necessary. In the space of just one hour, the salting trucks are on the road and driving their designated salting routes. Depending on the type of ice expected, 24 to 35 tons of road salt are then spread onto the roads per salting round. The vehicles take 2.5 to 3.5 hours to get the job done. If icy conditions persist (in the event of snowfall, for example), salting will continue. However, if salt is spread on snow and roads are then not used, the salt will mix with the snow insufficiently, because of which the snow will disappear just gradually. Given this fact, it is more likely that a snow plough or angle broom will be needed to clear snow from cycle paths than from roads used by car traffic. Bicycle traffic alone will not be enough to ensure that the salt mixes with the snow and dissolves.
Van der Bij stresses that “even an ice detection system will not eliminate icy road conditions altogether". He observes that the use of an ice detection system in combination with a weather forecast makes it possible to work out whether and when road conditions could become icy. Armed with a system like this, we can also see how much road salt is still present on a road surface and whether it's enough to keep icy road conditions at bay. Ultimately, common sense is critical too, which is why we always communicate with residents about our salting program and the likelihood of icy road conditions in the municipality throughout the winter months (via Twitter, for example). It's vital for them to be alert at all times, regardless of how good our forecasts and winter road management are.”