Article Operational Parameters of Logging Trucks Working in Mountainous Terrains of the Western Carpathians Michal Allman 1, Zuzana Dudáková 1,*, Martin Jankovský 2 and Ján Merganiˇc 1 1 Department of Forest Harvesting, Logistics and Ameliorations, Faculty of Forestry, Technical University in Zvolen, T.G. Masaryka 24, 960 01 Zvolen, Slovakia; [email protected] (M.A.); [email protected] (J.M.) 2 Department of Forestry Technology and Constructions, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 00 Prague 6–Suchdol, Czech Republic; jankovskym@fld.czu.cz * Correspondence: [email protected]; Tel.: +421-455-206-276 Abstract: Timber haulage is the last phase of the raw timber production process, necessary to transport timber to the customer. To improve the efficiency of logging truck operations, it is necessary to observe and assess several operational parameters through the electronic systems installed on the logging trucks. Measurements for this study were conducted for three logging truck types, which hauled 24,648 m3 of timber over 54,857 km and 1232 round trips. The RMC system was used for truck monitoring, equipped with a CAP04 capacitance sensor and a WGS 48 GPS module. The monitoring was continuous, lasting 27 to 74 weeks. Data acquired were evaluated via regression and correlation analyses and ANOVA. The results showed a moderately strong negative correlation between haulage productivity and haulage distance, ranging from r = −0.47 to r = −0.68. Simultaneously, a rather low efficiency of timber haulage was found for long-range haulage caused by legislation-based small utilization of the load-carrying capacity of the logging trucks. This showed in increased fuel consumption per production unit (2.01 Lm−3) as well as increased carbon emissions production −3 Citation: Allman, M.; Dudáková, Z.; (5.54 kg m ). Jankovský, M.; Merganiˇc,J. Operational Parameters of Logging Keywords: timber haulage; fuel consumption; logging truck; productivity Trucks Working in Mountainous Terrains of the Western Carpathians. Forests 2021, 12, 718. https:// doi.org/10.3390/f12060718 1. Introduction Timber haulage is an important link in the raw timber supply chain, with substantial Received: 27 April 2021 amounts of energy consumption and costs connected to it. Logging trucks, either equipped Accepted: 26 May 2021 with or without hydraulic manipulators, are the most abundant machines used in timber Published: 31 May 2021 haulage [1]. For example, in Finland, 75% of timber is transported to mills by trucks [2]. The rest, 25%, is transported to mills either by train (22%) or waterways (3%), though Publisher’s Note: MDPI stays neutral these, too, include roundwood trucking at the beginning of transportation chain (50 km on with regard to jurisdictional claims in average). A large majority of Sweden’s cargo is transported on the road and a special case published maps and institutional affil- of that is timber transports. The total fleet of timber trucks consists of over 1600 registered iations. trucks that transported 60 million tonnes of roundwood last year [3]. Furthermore, the State Forests National Forest Holding in Poland harvested over 42 million m3 of timber in 2018 and supplied it to several thousand recipients, which presented a major transportation challenge both in terms of logging operations and product transport. In most cases, approx- Copyright: © 2021 by the authors. imately 90% of the transport is conducted by vehicles using high-tonnage five- or six-axle Licensee MDPI, Basel, Switzerland. truck units [4]. This article is an open access article These trucks and their equipment are specifically designed for timber haulage and can distributed under the terms and be used to transport other goods only to a limited extent [5]. Other than their operation on conditions of the Creative Commons public roads, their design must enable their movement on the narrow, frequently unpaved, Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ forest roads [6]. Accounting for 40 to 60% of all transport costs, timber haulage is also 4.0/). the costliest transport operation [7]. In central Europe, timber haulage accounts for about Forests 2021, 12, 718. https://doi.org/10.3390/f12060718 https://www.mdpi.com/journal/forests Forests 2021, 12, 718 2 of 13 30% of the price of roundwood [8], whereas according to [9] it accounts for about 45% of the total operational costs of forest harvesting. A substantial portion of the costs is connected to fuel consumption, and [10] reports fuel costs are around 35% of the total operational costs of timber haulage in Sweden. Another substantial cost type in timber haulage is the investment cost. The whole investment cost of a low-bed truck consists of the price of the truck chassis and the platform, including mounting. The purchase price of a truck is between EUR 90,000 and EUR 110,000 (excluding value-added tax), with the purchase price level depending on the quality of the equipment installed and the number of axles (contractor interviews, 2005). The price of the trailer platform ranges from EUR 16,000 to EUR 21,000 (excluding the value-added tax) including installation costs [11]. Therefore, companies that operate logging trucks try to reduce their travel, thus increasing their efficiency and competitiveness [12]. According to [1], efficiency can be increased by optimizing routes, decreasing travel time, and increasing the cargo capacity, through fleet management systems. Furthermore, [13] and [14] state that reducing the variability of loads by their consistent maximization to the limits of the applicable public transport regulations are key to improving the efficiency of timber transport. In the USA, maintaining a uniform timber load weight can save approximately 4 to 14% of timber haulage operational costs [15]. Authors of [16] believe that between 5 and 10% of fuel can be saved by fitting wind deflectors and removing unnecessary accessories that can increase drag, such as signboards, extra air horns, extra lamps, among others. According to [17] and [18], timber transport contributes to environmental problems on various scales, ranging from local emissions to global climate change. In Sweden, [19] estimates that roundwood timber haulage accounts for an annual emission of 428,000 tons of CO2. The author of [20] argues that replacing 60 t vehicle combinations with 76 t vehicles could reduce the CO2 and NOx emissions by 32% and 41%, respectively, thus reducing the overall contribution of timber haulage to climate change. This study is focused on analysing the parameters of logging trucks used in different operational modes in mountainous terrains of the Western Carpathians. Based on the temporal analyses of particular operations, fuel consumption, and productivity, we aim to identify the main factors affecting these parameters in the various operational modes, thus enabling the improvement of timber haulage efficiency, productivity, and reduction of its CO2 emissions. 2. Materials and Methods Measurements were conducted on three types of logging trucks owned by the Univer- sity Forest Enterprise of the Technical University in Zvolen (UFE). The University Forest Enterprise managed forests in three geographic areas—the Kremnica mountains, Stiavnica mountains, and Javorie—covering 9724 ha of forest land. Natural conditions were variable, with altitudes ranging from 250 to 1025 m asl. The forest enterprise was organized into a headquarters (located in Zvolen, Slovakia), forest district (in Budˇca),and a conversion depot (in Lieskovec). Deciduous trees, mainly beeches, oaks, and hornbeams, accounted for approximately 82% of all trees in the forest stands; the remainder was composed of mainly spruces and firs. The annual volume of harvested timber was 36,991 m3 (2020), including broadleaves (28,307 m3) and coniferous (8684 m3). The forest road density at the UFE was about 47.5 m/ha−1. Almost 120,000 m of roads were suitable for timber haulage, either year- round (the so-called 1L-type roads) or seasonally (the so-called 2L-type roads). These were used by logging trucks owned by the UFE or by machines owned by companies contracted to perform timber haulage for the UFE. The University Forest Enterprise owned several logging trucks equipped for primary and secondary timber haulage. Stems and longwood (max. 12 m long) were hauled in primary haulage by stinger-steered log trailer trucks and fixed-length log trailer trucks owned by the UFE from roadside landings to the conversion depot, where the timber was converted into assortments. Secondary haulage of pulpwood (4 m long assortments) was secured by fixed-length log trailer trucks from the roadside Forests 2021, 12, 718 3 of 13 landings or the conversion depot to the paper mill in Ružomberok (approximately 70 km from the headquarters in Zvolen). The University Forest Enterprise operates 195 roadside landings with a minimal haulage distance of 6.4 km and maximal distance of 29.8 km from the conversion depot in Lieskovec. Observations of operational parameters were conducted on three different types of logging trucks employed in both primary and secondary haulage and were owned by the UFE: 1. SCANIA P450—made by Scania AB, Södertälje, Sweden (truck with stinger-steered trailer and a hydraulic manipulator) for primary haulage (P4), 2. SCANIA G500—made by Scania AB, Södertälje, Sweden (truck with a fixed-length log trailer and a hydraulic manipulator) for primary haulage and loading of logging trucks for secondary