# A New Method for Haul Road Design in Open-Pit Mines to Support Efficient Truck Haulage Operations
## 1 Introduction  
Designing an efficient haul road for the movement of mining equipment in open-pit mines is of critical importance because the cost of transporting ore and waste can vary greatly depending on the road design results [1]. Many guides on road design in open-pit mines have been developed to date [1; 2; 3; 4; 5]. These guides describe the design of the width, slope, and curvature of haul roads to secure the safety of truck haulage operations, as well as road construction and maintenance procedures. However, one limitation of these guides is that they do not present a road design method capable of supporting efficient truck haulage operations over the entire lifecycle of an open-pit mine. In recent years, computer designs have become generalized, and many software applications such as Autodes's AutoCAD Civil 3D (2017, San Rafael, CA, USA) [6], Dassault System's GEMS (2017, Paris, France) [7], Carlson's Civil and Mining Suites (2017, Maysville, KY, USA) [8], and Maptek's Vulcan (2017, Golden, CO, USA) [9] have been developed for the mining industry and are used for the design of open-pit mines. These applications provide features related to road design in open-pit mines. For example, AutoCAD Civil 3D can automatically design a road when design parameter values such as the topographic data of an open-pit mine, the road layout, the road width and slope, and the cut and fill slope are specified [10] (see Figure 1). GEMS enables the user to set the road slope, the horizontal and vertical distances, and the direction of progress (that is, in a direction to the left or right based on the selected bench) via the user interface, upon which the application designs the haulroad segment interconnecting the top and bottom benches and presents the results in combination with three-dimensional (3D) topography [11]. Therefore, these software applications allow the haul road design of an open-pit mine to be performed more effectively and efficiently by applying the criteria suggested in existing guides. However, even when an open-pit mine is designed using these software applications, the user must determine the overall road layout, which is used as input data, by performing a separate analysis (see Figure 1). Since the mining software applications do not provide a feature for optimizing the road layout in open-pit mines to support efficient truck haulage operations, these tasks are mostly carried out by relying on the empirical and subjective judgment of mining engineers. The determination of the appropriate road layout in open-pit mines to support efficient truck haulage operations requires the application of a spatial optimization technique [12]. In this regard, raster-based least-cost path analysis (LCPA) is a representative spatial optimization technique used in a variety of fields [13]. This technique is useful for analyzing the optimum travel path that can minimize the cost (time, distance, resistance, fuel consumption, etc.) in an area with no travel path network such as roads and railroads [14; 15]. The LCPA method consists of two steps [14]. First, the cost of passing every cell from the origin is calculated based on the cost surface data, which contains the cost of passing each cell, and these values are recorded in every cell [16]. Next, the least-cost path is derived using the back-link mechanism based on the calculation results of the accumulated travel cost recorded in all cells [17]. A detailed explanation of the raster-based LCPA method was published by [PERSON] [18]. The raster-based LCPA method has mainly been used to analyze and determine the optimum path at the local scale such as paths for a pipeline [19], mountain climbing [20], a temporary haulage road interconnecting a mine and a port [21], a power line [22], material transportation at a construction site [23], and an expressway [24]. Recently, studies were conducted to optimize truck haulage paths by applying the raster-based LCPA to open-pit mines. [PERSON] et al.