# Application of the Clark-Wright Method to Improve the Sustainability of the Logistic Chain
## 6 Discussion  
Based on the results brought by the application of the Clark-Wright method for the optimization of waste collection processes in the Zilina region, several key aspects are revealed that have a significant impact on the efficiency and sustainability of the waste collection process. First, we compare the previous and new routes, focusing on changes in route length, fuel consumption, and the number of routes needed to cover the entire area. We evaluate these results in terms of cost effectiveness as well as in terms of environmental impact. This paper presents a proposal to change the way municipal waste is collected to optimize material flows in a selected region. The paper proposes the use of the Clark-Wright method to efficiently create new, effective routes for waste collection. The Clark-Wright method was chosen for its ability to minimize the number of vehicles and significantly reduce the distances required, thereby contributing to cost savings and reduced environmental impact. The aim of the paper was to achieve optimal routing of vehicles to shorten transport distances, which was achieved. The result is newly designed routes in the city of Zilina and its surroundings. Within the city of Zilina, a total of eleven new municipal waste collection routes were designed, which would serve 245 collection points out of a total of 303 points. The largest share of all the newly created routes obtained by calculation are the routes serving the surrounding settlements. A total of 39 new routes including only the surrounding area were calculated in this way, as part of the merging of two routes into one day, 19 of which were assigned to others, which resulted in only 20 new routes, one of which is formed by only one calculated route and the other routes by two calculated routes. The original distance traveled was obtained from the company's internal documents; with the current route, its value is 4896 km. The new value of the total mileage was determined from the above tabular overviews of the new proposed routes. The total mileage for all routes within one working week is 2447 km, which is almost half of the original distance. The savings in the distance traveled after the introduction of the new routing amounts to 2449 km. By reducing the distance traveled with the help of the new routing of waste collection routes, it is possible to save 1469.4 liters of fuel annually. In addition to the mentioned reduction in distances, the proposed solution also has an impact on the total number of routes required to service the entire territory. Specifically, there was a reduction from the original 65 routes per week to 45 routes. There are two main reasons for this savings. On the one hand, there was a saving in the distance traveled on all routes, which resulted in a smaller need for vehicles to serve the required routes. The second reason is due to one of the conditions of the used optimization method, which serves each point exactly once when constructing new routes. This prevents the random repetition of service of some collection points several times a week. In the current state, some containers are emptied several times a week, even though this is not necessarily due to their capacity. By removing this randomness of the service, the total length of all routes would be further reduced. The service time of the assigned circuit changes only depending on the indicated indicator, the total distance traveled. The fact that the new routing is calculated to minimize the total length of all routes also minimizes the total time needed to service them. This time savings was used in the proposal, e.g., when combining several routes into one day, which led to saving on the number of vehicles needed for service. By reducing the number of routes needed to serve the entire assigned territory, there was also a reduction in the number of vehicles needed to remove waste from the entire territory.