# Introduction of a New Index of Field Operations Efficiency
## 1 Introduction  
An operational system in agricultural field operation consists of tangible entities (i.e., a field), implementing entities (i.e., machines), and operating features (i.e., driving direction, fieldwork pattern, etc.). Field efficiency is a time-based measure for the productivity of an operational system, and it is defined as the ratio between the effective time and the total time (effective time plus non-productive time) used to execute an operation [1]. Field efficiency is directly connected with the economic performance of the operating system [2; 3; 4; 5; 6; 7].  
The non-productive time elements include: turning times; in-field preparations, maintenance, adjustments, breakdowns and repairs; in-field transport time; in-field loading/unloading time; and idle time of primary unit (i.e., a harvester) waiting for a service unit (transporting trailer). A large number of these factors, such as in-field preparations, adjustments, breakdowns etc. are factors that are not predictable and highly depended on the operator's abilities and experience, current field conditions, and on factors that are highly stochastic (e.g., breakdowns). This is the reason that the field efficiency is generally provided by average norms. Typical average values for field efficiency of agricultural operations ranged between 50-90% [1]. These norms are of limited value when a decision have to be made on the selection of the appropriate machinery system for a specific operational setup (i.e., fieldwork pattern, driving direction, operating width, machine maneuverability, and field shape), especially in the case of precision agriculture practices that requires specific and specialized operational configurations [8; 9; 10]. A number of studies have been dedicated to develop field indices for estimating operational efficiency [7; 11; 12; 13]. However, due to the variation of shape and size of fields, there are no general shape indices for estimating field efficiency of any types of fields so far. To this end, a measure of the field efficiency tailored to the specific operational system is needed.  
The driving distance during a field operation is a function of the above-mentioned operational specifications, i.e., field shape (tangible feature); operating width and agricultural vehicle maneuverability (implementing features) [14]; and field-work pattern and driving direction (operating features), meaning that if these specifications are quantified then the driving distance can be estimated. Furthermore, the driving distance is composed of the productive driving distance and the non-productive driving distance (i.e., headland turning distance, field entering/exiting travelled distance).  
In this paper we propose a new more objective and measurable index for the field efficiency based on the travelled distance of an agricultural machinery during a field operation, the field traversing efficiency (FTE), as a function of well-quantified operational specifications. For the purposes of calculating the FTE, a dedicated tool that generates a continuous field area coverage path was also developed to estimate the total travelled distance and the various distance elements (e.g., turnings) this path consists of, and also to categorize the path's various segments to productive and non-productive ones. The tool comprises three modules, the field representation module and the connectors' generator module, and the continuous path generator module. In the first module, all fixed distance elements (field-work tracks, headland passes) are identified by taking into account the field shape, the operating width, and the driving direction, while in the second module, all inter-connections between the fixed elements are generated by taking into account the machine maneuverability. In the third module a continuous path is generated based on an undirected graph converted from the field geometrical representation.