**3. Results and discussion**

First, only environmental impacts associated with the operation of WRM vehicles in two alternative scenarios were evaluated. The results show that the production of road salt (rock salt respectively) required for gritting the road yields significantly higher environmental impacts than the operation of the WRM vehicle itself. Production of road salt contributes 90% or more to the total parameter value of all impacts categories, the only exception is the impact on ozone layer depletion potential, where salt contributes around 70% of the total parameter value. Operation of the WRM vehicle is associated with diesel fuel requirements and exhaust gas emissions due to fuel combustion. These kinds of environmental impacts are thus relatively minor compared to impacts associated with salt gritting. Those are even


#### **Table 3.**

*ReCiPe 2016 midpoint impact categories.*

underestimated in this LCA study, as impacts of salt flushed into water or terrestrial ecosystems are not possible to evaluate by means of LCA. The fate of road salt released in the environment is poorly understood and because of this reason, no characterization factors for leaching of salt into the natural environment have been introduced in LCA [5, 7, 9].

A comparison of two scenarios shows that the use of the Road-Weather Information System can significantly contribute to a reduction of environmental impacts related to the operation of winter road maintenance. This is a direct consequence of optimization in the consumption of salt for gritting the road. In this specific case study, the WRM agency reported that they saved 40% of road salt due to preventive winter road maintenance operations. Environmental impacts were reduced between 43% (in case of photochemical ozone creation potential—POCP) and 36% (in case of ozone layer depletion potential—ODP) compared to the baseline WRM operation scenario. In most of the impact categories, the impacts were reduced by 39% (including in the case of global warming potential—GWP, abiotic depletion of fossil fuels—ADP-f, and human toxicity potential—HTP). Optimization of the operation of winter road maintenance in terms of less operational activities of the vehicle (e.g., less fuel consumption due to a lower number of travels along road section and conducting only gritting, no plowing) yields relatively minor contribution to environmental improvement of preventive WRM operation scenario compared to baseline WRM operation scenario (**Figure 3**).

**Figure 3.**

*Global warming potential associated with the operation of WRM vehicle (salt gritting, fuel consumption, and related exhaust gases) in two benchmarked scenarios.*

In addition, two scenarios were compared by means of LCA holistically, accounting also environmental impacts caused by road traffic (passenger cars and trucks) passing the road section during a weather event. In such a case, the LCA results are greatly influenced by density of road traffic. Denser the traffic is, the higher is its contribution to the environmental impact of the studied system. It was assumed that road traffic in demanding winter conditions (due to snow accumulation on the road) consumes 10% of fuel more than in normal driving conditions (snow-free road). In case of baseline scenario, the traffic contributes around 80–90% of the total parameter values, depending on the impact category (the contribution is 84% in case of global warming potential—**Figure 4**). The rest of the influence is mostly affected by road salt, while the contribution of WRM vehicles is reasonably minor as already discussed. In a scenario with preventive WRM operation, environmental loads are reduced typically by 14% (GWP for example) compared to the baseline scenario. However, the impact on ionizing radiation is reduced even by 31%, due to less salt (anti-icing agent) consumption (**Figure 5**). Mining of rock salt is associated with electricity requirements. Taking into account that an important share of European electricity derives from nuclear power plants, such electricity yields a relatively high ionizing radiation footprint. This footprint is accounted also to resources (e.g., rock salt) for which exploitation requires electrical power. Moreover, an important share of electricity derives from thermal power plants. For this reason, mining of rock salt yields also relatively high impacts on fine particulate matter formation (PM 2.5), photochemical ozone formation (POCP), and acidification potential (AP). Because of less consumption of salt in preventive WRM operation scenarios, impacts on these three impact categories are also quite significantly reduced (PM 2.5 for 19%, POCP for 18%, and AP for 17%) (**Figure 5**).

*Pathway toward Sustainable Winter Road Maintenance (Case Study) DOI: http://dx.doi.org/10.5772/intechopen.110764*

#### **Figure 4.**

*Global warming potential of baseline WRM operation scenario versus preventive WRM operation scenario. Contributions of road salt, WRM vehicle (fuel consumption and associated exhaust emissions), and road traffic (fuel consumption and associated exhaust emissions) to GWP are shown in absolute and relative values.*

#### **Figure 5.**

*Relative comparison of two scenarios. Baseline WRM operation scenario is set as a reference.*
