Patent Publication Number: US-2012036140-A1

Title: Methods and apparatus for analyzing locate and marking operations by comparing filtered locate and/or marking information

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims a priority benefit, under 35 U.S.C. §119(a), to Canadian Application Serial No. (not yet assigned) entitled “Methods and Apparatus for Analyzing Locate and Marking Operations by Comparing Filtered Locate and/or Marking Information, filed on Aug. 4, 2010 under attorney docket no. PAT 71776-1 CA which application is incorporated by reference herein in its entirety. 
     BACKGROUND 
     Field service operations may be any operation in which companies dispatch technicians and/or other staff to perform certain activities, for example, installations, services and/or repairs. Field service operations may exist in various industries, examples of which include, but are not limited to, network installations, utility installations, security systems, construction, medical equipment, heating, ventilating and air conditioning (HVAC) and the like. 
     An example of a field service operation in the construction industry is a so-called “locate and marking operation,” also commonly referred to more simply as a “locate operation” (or sometimes merely as “a locate”). In a typical locate operation, a locate technician visits a work site in which there is a plan to disturb the ground (e.g., excavate, dig one or more holes and/or trenches, bore, etc.) so as to determine a presence or an absence of one or more underground facilities (such as various types of utility cables and pipes) in a dig area to be excavated or disturbed at the work site. In some instances, a locate operation may be requested for a “design” project, in which there may be no immediate plan to excavate or otherwise disturb the ground, but nonetheless information about a presence or absence of one or more underground facilities at a work site may be valuable to inform a planning, permitting and/or engineering design phase of a future construction project. 
     In many states, an excavator who plans to disturb ground at a work site is required by law to notify any potentially affected underground facility owners prior to undertaking an excavation activity. Advanced notice of excavation activities may be provided by an excavator (or another party) by contacting a “one-call center.” One-call centers typically are operated by a consortium of underground facility owners for the purposes of receiving excavation notices and in turn notifying facility owners and/or their agents of a plan to excavate. As part of an advanced notification, excavators typically provide to the one-call center various information relating to the planned activity, including a location (e.g., address) of the work site and a description of the dig area to be excavated or otherwise disturbed at the work site. 
       FIG. 1  illustrates an example in which a locate operation is initiated as a result of an excavator  110  providing an excavation notice to a one-call center  120 . An excavation notice also is commonly referred to as a “locate request,” and may be provided by the excavator to the one-call center via an electronic mail message, information entry via a web site maintained by the one-call center, or a telephone conversation between the excavator and a human operator at the one-call center. The locate request may include an address or some other location-related information describing the geographic location of a work site at which the excavation is to be performed, as well as a description of the dig area (e.g., a text description), such as its location relative to certain landmarks and/or its approximate dimensions, within which there is a plan to disturb the ground at the work site. One-call centers similarly may receive locate requests for design projects (for which, as discussed above, there may be no immediate plan to excavate or otherwise disturb the ground). 
     Using the information provided in a locate request for planned excavation or design projects, the one-call center identifies certain underground facilities that may be present at the indicated work site. For this purpose, many one-call centers typically maintain a collection “polygon maps” which indicate, within a given geographic area over which the one-call center has jurisdiction, generally where underground facilities may be found relative to some geographic reference frame or coordinate system. 
     Polygon maps typically are provided to the one-call centers by underground facilities owners within the jurisdiction of the one call center (“members” of the one-call center). A one-call center first provides the facility owner/member with one or more maps (e.g., street or property maps) within the jurisdiction, on which are superimposed some type of grid or coordinate system employed by the one-call center as a geographic frame of reference. Using the maps provided by the one-call center, the respective facilities owners/members draw one or more polygons on each map to indicate an area within which their facilities generally are disposed underground (without indicating the facilities themselves). These polygons themselves do not precisely indicate geographic locations of respective underground facilities; rather, the area enclosed by a given polygon generally provides an over-inclusive indication of where a given facilities owner&#39;s underground facilities are disposed. Different facilities owners/members may draw polygons of different sizes around areas including their underground facilities, and in some instances such polygons can cover appreciably large geographic regions (e.g., an entire subdivision of a residential area), which may further obfuscate the actual/precise location of respective underground facilities. 
     Based on the polygon maps collected from the facilities owners/members, the one-call center may in some instances create composite polygon maps to show polygons of multiple different members on a single map. Whether using single member or composite polygon maps, the one-call center examines the address or location information provided in the locate request and identifies a significant buffer zone around an identified work site so as to make an over-inclusive identification of facilities owners/members that may have underground facilities present (e.g., to err on the side of caution). In particular, based on this generally over-inclusive buffer zone around the identified work site (and in some instances significantly over-inclusive buffer zone), the one-call center consults the polygon maps to identify which member polygons intersect with all or a portion of the buffer zone so as to notify these underground facility owners/members and/or their agents of the proposed excavation or design project. Again, it should be appreciated that the buffer zones around an indicated work site utilized by one-call centers for this purpose typically embrace a geographic area that includes but goes well beyond the actual work site, and in many cases the geographic area enclosed by a buffer zone is significantly larger than the actual dig area in which excavation or other similar activities are planned. Similarly, as noted above, the area enclosed by a given member polygon generally does not provide a precise indication of where one or more underground facilities may in fact be found. 
     In some instances, one-call centers may also or alternatively have access to various existing maps of underground facilities in their jurisdiction, referred to as “facilities maps.” Facilities maps typically are maintained by facilities owners/members within the jurisdiction and show, for respective different utility types, where underground facilities purportedly may be found relative to some geographic reference frame or coordinate system (e.g., a grid, a street or property map, GPS latitude and longitude coordinates, etc.). Facilities maps generally provide somewhat more detail than polygon maps provided by facilities owners/members; however, in some instances the information contained in facilities maps may not be accurate and/or complete. For at least this reason, whether using polygon maps or facilities maps, as noted above the one-call center utilizes a significant buffer zone around an identified work site so as to make an over-inclusive identification of facilities owners/members that may have underground facilities present. 
     Once facilities implicated by the locate request are identified by a one-call center (e.g., via the polygon map/buffer zone process), the one-call center generates a “locate request ticket” (also known as a “locate ticket,” or simply a “ticket”). The locate request ticket essentially constitutes an instruction to inspect a work site and typically identifies the work site of the proposed excavation or design and a description of the dig area, typically lists on the ticket all of the underground facilities that may be present at the work site (e.g., by providing a member code for the facility owner whose polygon falls within a given buffer zone), and may also include various other information relevant to the proposed excavation or design (e.g., the name of the excavation company, a name of a property owner or party contracting the excavation company to perform the excavation, etc.). The one-call center sends the ticket to one or more underground facility owners  140  and/or one or more locate service providers  130  (who may be acting as contracted agents of the facility owners) so that they can conduct a locate and marking operation to verify a presence or absence of the underground facilities in the dig area. For example, in some instances, a given underground facility owner  140  may operate its own fleet of locate technicians (e.g., locate technician  145 ), in which case the one-call center  120  may send the ticket to the underground facility owner  140 . In other instances, a given facility owner may contract with a locate service provider to receive locate request tickets and perform a locate and/or marking operation in response to received tickets on their behalf. 
     Upon receiving the locate ticket, a locate service provider or a facility owner (hereafter referred to as a “ticket recipient”) may dispatch a locate technician to the work site of planned excavation to determine a presence or absence of one or more underground facilities in the dig area to be excavated or otherwise disturbed. A typical first step for the locate technician includes utilizing an underground facility “locate device,” which is an instrument or set of instruments (also referred to commonly as a “locate set”) for detecting facilities that are concealed in some manner, such as cables and pipes that are located underground. The locate device is employed by the technician to verify the presence or absence of underground facilities indicated in the locate request ticket as potentially present in the dig area (e.g., via the facility owner member codes listed in the ticket). This process is often referred to as a “locate operation.” 
     In one example of a locate operation, an underground facility locate device is used to detect electromagnetic fields that are generated by an applied signal provided along a length of a target facility to be identified. In this example, a locate device may include both a signal transmitter to provide the applied signal (e.g., which is coupled by the locate technician to a tracer wire disposed along a length of a facility), and a signal receiver which is generally a hand-held apparatus carried by the locate technician as the technician walks around the dig area to search for underground facilities. The transmitter is connected via a connection point to a target object (in this example, underground facility) located in the ground, and generates the applied signal coupled to the underground facility via the connection point (e.g., to a tracer wire along the facility), resulting in the generation of a magnetic field. The magnetic field in turn is detected by the locate receiver, which itself may include one or more detection antenna. The locate receiver indicates a presence of a facility when it detects electromagnetic fields arising from the applied signal. Conversely, the absence of a signal detected by the locate receiver generally indicates the absence of the target facility. 
     In yet another example, a locate device employed for a locate operation may include a single instrument, similar in some respects to a conventional metal detector. In particular, such an instrument may include an oscillator to generate an alternating current that passes through a coil, which in turn produces a first magnetic field. If a piece of electrically conductive metal is in close proximity to the coil (e.g., if an underground facility having a metal component is below/near the coil of the instrument), eddy currents are induced in the metal and the metal produces its own magnetic field, which in turn affects the first magnetic field. The instrument may include a second coil to measure changes to the first magnetic field, thereby facilitating detection of metallic objects. 
     In addition to the locate operation, the locate technician also generally performs a “marking operation,” in which the technician marks the presence (and in some cases the absence) of a given underground facility in the dig area based on the various signals detected (or not detected) during the locate operation. For this purpose, the locate technician conventionally utilizes a “marking device” to dispense a marking material on, for example, the ground, pavement, or other surface along a detected underground facility. Marking material may be any material, substance, compound, and/or element, used or which may be used separately or in combination to mark, signify, and/or indicate. Examples of marking materials may include, but are not limited to, paint, chalk, dye, and/or iron. Marking devices, such as paint marking wands and/or paint marking wheels, provide a convenient method of dispensing marking materials onto surfaces, such as onto the surface of the ground or pavement. 
     In some environments, arrows, flags, darts, or other types of physical marks may be used to mark the presence or absence of an underground facility in a dig area, in addition to or as an alternative to a material applied to the ground (such as paint, chalk, dye, tape) along the path of a detected utility. The marks resulting from any of a wide variety of materials and/or objects used to indicate a presence or absence of underground facilities generally are referred to as “locate marks.” Often, different color materials and/or physical objects may be used for locate marks, wherein different colors correspond to different utility types. For example, the American Public Works Association (APWA) has established a standardized color-coding system for utility identification for use by public agencies, utilities, contractors and various groups involved in ground excavation (e.g., red=electric power lines and cables; blue=potable water; orange=telecommunication lines; yellow=gas, oil, steam). In some cases, the technician also may provide one or more marks to indicate that no facility was found in the dig area (sometimes referred to as a “clear”). 
     As mentioned above, the foregoing activity of identifying and marking a presence or absence of one or more underground facilities generally is referred to for completeness as a “locate and marking operation.” However, in light of common parlance adopted in the construction industry, and/or for the sake of brevity, one or both of the respective locate and marking functions may be referred to in some instances simply as a “locate operation” or a “locate” (i.e., without making any specific reference to the marking function). Accordingly, it should be appreciated that any reference in the relevant arts to the task of a locate technician simply as a “locate operation” or a “locate” does not necessarily exclude or include the marking portion of the overall process. At the same time, in some contexts a locate operation is identified separately from a marking operation, wherein the former relates more specifically to detection-related activities and the latter relates more specifically to marking-related activities. 
     Inaccurate locating and/or marking of underground facilities can result in physical damage to the facilities, property damage, and/or personal injury during the excavation process that, in turn, can expose a facility owner or contractor to significant legal liability. When underground facilities are damaged and/or when property damage or personal injury results from damaging an underground facility during an excavation, the excavator may assert that the facility was not accurately located and/or marked by a locate technician, while the locate contractor who dispatched the technician may in turn assert that the facility was indeed properly located and marked. Proving whether the underground facility was properly located and marked can be difficult after the excavation (or after some damage, e.g., a gas explosion), because in many cases the physical locate marks (e.g., the marking material or other physical marks used to mark the facility on the surface of the dig area) will have been disturbed or destroyed during the excavation process (and/or damage resulting from excavation). 
     SUMMARY 
     As discussed above, in various field service operations, a number of field technicians typically are dispatched to perform field operations at any given time, and over any given time period each technician may be assigned numerous work orders, or “tickets” specifying aspects of the field operations to be performed. The volume of tickets per technician may be particularly high in the construction industry, especially in connection with locate and marking operations. The inventors have recognized and appreciated that implementing and performing meaningful oversight and quality control activities in a timely fashion for several field technicians each performing several field operations in a given time period may present challenges, and that failure to perform meaningful oversight and quality control activities may adversely affect customer satisfaction. 
     Additionally, the inventors have appreciated that the time, effort, and cost that is associated with re-performing work in the field, or with correcting and/or improving poorly performed field calls, may be unacceptable. Consequently, the inventors have realized that a need exists for methods of providing oversight and quality control in field service operations in order to improve customer satisfaction, to identify and reduce the number of poorly performed tickets, and to improve visibility into distributed workforce operations. 
     In view of the foregoing, various inventive embodiments disclosed herein relate generally to methods, apparatus and systems for computer-aided determination of quality assessment for locate and/or marking operations. In some embodiments, a quality assessment decision may be solely under the discretion of a human reviewer, albeit facilitated in some respects by computer-aided display of information, and electronic record-keeping and communication functions associated with the quality assessment result(s). In other embodiments, information related to a locate and marking operation is electronically analyzed such that a quality assessment is not based solely on human discretion, but rather based at least in part on some predetermined criteria and/or metrics that facilitate an automated determination of quality assessment. 
     More specifically, in some embodiments, methods, apparatus and systems according to the present disclosure relate to at least partially automating oversight and quality assessment in underground facility locate and/or marking operations. For example, in some embodiments, an automated quality assessment system may receive information related to a locate and/or marking operation from one or more sources of electronic data (also referred to herein as “field information” or “field data”), analyze the contents of the received electronic data, and automatically assess the quality of the locate and/or marking operation based at least in part on the analysis. In other embodiments, automated analysis of at least some of the received electronic data relating to the locate and/or marking operation facilitates further analysis and/or quality assessment by a human, in which the quality assessment is not based solely on the discretion of the human, but is significantly informed in some manner by automated analysis of data. 
     In some exemplary implementations in which a quality of a locate and/or marking operation is assessed via an at least partially automated process, some or all of the available field information (e.g., which in some instances is derived from data contained in one or more electronic records of the locate and/or marking operation) is compared to “reference information” or “reference data” (which in some instances is derived from data contained in one or more “reference” electronic records). Examples of types of reference information/data used in a quality assessment process according to various embodiments discussed herein may include, but are not limited to: 1) information/data derived from or relating to one or more facilities maps that illustrate the presumed locations of underground facilities purportedly present in a geographic area proximate to or surrounding and subsuming the work site; 2) information/data derived from or relating to one or more previous locate and/or marking operations at or near the work site (referred to herein as “historical tickets” or “historical data”); 3) information/data relating to one or more environmental landmarks present in a geographic area proximate to or surrounding and subsuming the dig area (e.g., the work site and its environs), or within the dig area itself (referred to herein as “landmark information,” which may be available, for example, from facilities maps, historical tickets, and/or field data collected at or around the time of the locate and/or marking operation being assessed); and/or 4) another type of field information (e.g., first field information may be compared with reference information in the form of second field information different from the first field information). 
     More specifically, in some embodiments, different types of field information may be compared to each other. For example, in some embodiments discussed in detail herein, first field information relating to a marking operation (“marking information”) may be compared with reference information in the form of second field information relating to a locate operation (“locate information”). It should be appreciated that in embodiments in which different types of field information are compared with each other, the distinction between “field information” and “reference information” may not have any practical effect; however, for various reasons, in some implementations it may be desirable to designate one type of the field information as the “reference information” for purposes of comparison (e.g., it may be presumed a priori that a first type of field information is generally more reliable than a second type of field information, and that hence the first type of field information is taken as the “reference information” for purposes of comparative analysis). 
     In one aspect of embodiments in which marking information and locate information are compared with each other, the marking information and the locate information may pertain to the same work site/dig area and represent corresponding locate and marking operations both performed in response to the same locate request ticket (such that the marking information and locate information essentially are obtained concurrently). In another aspect, the marking information and the locate information may pertain to the same work site/dig area, but one of the marking information and the locate information may have been acquired in connection with performance of a different locate request ticket (e.g., one of the marking information and the locate information may be obtained from a “historical ticket”). With respect to one of the marking information and the locate information being obtained from a historical ticket, it should be appreciated that the same technician may or may not have been responsible for obtaining the respective marking information and locate information forming the basis of the comparative analysis. 
     In other aspects, the quality assessment of a locate and/or marking operation may be performed, in whole or in part, by one or more analysis components (e.g., one or more processors executing instructions) separate and/or remote from the locate and/or marking device used in connection with a locate and/or marking operation. Alternatively, the assessment may be performed, in whole or in part, by one or more analysis components incorporated within or otherwise coupled to a locate device, a marking device, and/or a combined locate and marking device. Depending on the nature of the assessment, it may be performed substantially in real time with respect to the generation of field information/data used in connection with the assessment (e.g., one or more of locate information, marking information and landmark information contained in electronic records of a locate and marking operation and/or an electronic manifest of same), otherwise during a locate and/or marking operation, or after completion of a locate and/or marking operation. 
     In some embodiments described herein, a notification may be generated based on the quality assessment performed. The notification may provide one or more indications of the quality of the locate and/or marking operation as a whole, or of some aspect thereof. For example, the notification may provide an indication of a degree of correspondence or discrepancy between different types of field data contained in one or more electronic records of the locate and/or marking operation (e.g., marking information compared with locate information), and/or between field data and reference data contained in one or more reference electronic records. Likewise, the notification may provide an indication that the locate and/or marking operation is or is not approved based on the comparison of different types of filed data, and/or the comparison of field data to selected reference data. The notification may be transmitted electronically or otherwise conveyed, for example, to one or more parties associated with one or more underground facilities within the dig area or in a geographic area proximate to or surrounding and subsuming the work site, one or more parties associated with the performance or oversight of the locate and/or marking operation, and/or one or more parties associated with excavation of the dig area, for example. 
     In some embodiments, a first electronic representation of first field information relating to a locate and/or marking operation (e.g., data in one or more electronic records, an electronic manifest, etc.), as well as a second electronic representation of either second field information or reference information (e.g., data in a reference electronic record from any of a variety of sources) to which the first electronic representation is compared, may be visually rendered (e.g., via a computer-generated visual representation in a display field) such that the electronic representations are overlaid to provide a visual aid to an automated assessment process. In some implementations, the visual aid may be viewed by a human to assess the quality of the locate and/or marking operation. In one exemplary implementation discussed in detail herein, a first electronic representation of first field information including marking information, and a second electronic representation of second field information including locate information, are visually rendered in a display field to facilitate comparative viewing of the marking information and the locate information. 
     In sum, one embodiment of the present invention is directed to a method, executed in a computer comprising at least one hardware processor, at least one tangible storage medium, and at least one input/output (I/O) interface, for evaluating a quality of a locate operation and/or a marking operation to identify a presence or an absence of at least one underground facility at a work site. The method comprises: A) comparing marking information relating to the marking operation to locate information relating to the locate operation; B) automatically generating, based on A), at least one indication of a quality assessment of the locate and/or marking operation; and C) electronically storing on the at least one tangible storage medium, and/or electronically transmitting via the at least one I/O interface, the at least one indication of the quality assessment so as to provide an electronic record of the quality assessment. 
     Another embodiment is directed to an apparatus for evaluating a quality of a locate and/or marking operation to identify a presence or an absence of at least one underground facility at a work site. The apparatus comprises: at least one input/output (I/O) interface; at least one memory storing processor-executable instructions; and a processor coupled to the memory and the at least one I/O interface, wherein upon execution of the processor-executable instructions by the processor, the processor: A) compares marking information relating to the marking operation to locate information relating to the locate operation; B) automatically generates, based on A), at least one indication of a quality assessment of the locate and/or marking operation; and C) controls the at least one memory so as to electronically store, and/or controls the at least one I/O interface so as to electronically transmit, the at least one indication of the quality assessment so as to provide an electronic record of the quality assessment. 
     Another embodiment is directed to at least one computer-readable storage medium encoded with instructions that, when executed by a processor in a computer comprising at least one input/output (I/O) interface, perform a method for evaluating a quality of a locate and/or marking operation to identify a presence or an absence of at least one underground facility within a work site. The method comprises: A) comparing marking information relating to the marking operation to locate information relating to the locate operation; B) automatically generating, based on A), at least one indication of a quality assessment of the locate and marking operation; and C) electronically storing on the at least one computer-readable storage medium, and/or electronically transmitting via the at least one I/O interface, the at least one indication of the quality assessment so as to provide an electronic record of the quality assessment. 
     Another embodiment is directed to an apparatus for automatically assessing a quality of a locate and/or marking operation. The apparatus comprises: a memory storing processor-executable instructions; at least one I/O interface; and a processor coupled to the memory and the at least one I/O interface, wherein upon execution of the processor-executable instructions, the processor: A) identifies at least one first geographic location at which at least one facility line of at least one underground facility was marked during the marking operation; B) obtains marking geo-location data based on A); C) identifies at least one first geographic location at which at least one facility line of at least one underground facility was detected during the locate operation; D) obtains locate geo-location data based C); E) determines a measure of distances between the marking geo-location data and the locate geo-location data; F) assesses the quality of the locate and/or marking operation based at least in part on E); and G) generates at least one indication of a quality assessment based on F). 
     Another embodiment is directed to a method, performed in a computer comprising at least one hardware processor, at least one tangible storage medium, and at least one input/output (I/O) interface, for assessing a locate operation and/or a marking operation to identify a presence or an absence of at least one underground facility at a work site. The method comprises: A) filtering at least one of marking information relating to the marking operation and locate information relating to the locate operation so as to provide filtered information; and B) comparing the marking information to the locate information, wherein at least one of the marking information and the locate information includes the filtered information. 
     Another embodiment is directed to an apparatus for assessing a locate and/or marking operation to identify a presence or an absence of at least one underground facility at a work site. The apparatus comprises: at least one input/output (I/O) interface; at least one memory storing processor-executable instructions; and a processor coupled to the memory and the at least one I/O interface. Upon execution of the processor-executable instructions by the processor, the processor: A) filters at least one of marking information relating to the marking operation and locate information relating to the locate operation so as to provide filtered information; and B) compares the marking information to the locate information, wherein at least one of the marking information and the locate information includes the filtered information. 
     Another embodiment is directed to at least one computer-readable storage medium encoded with instructions that, when executed by a processor in a computer comprising at least one input/output (I/O) interface, perform a method for assessing a locate and/or marking operation to identify a presence or an absence of at least one underground facility within a work site. The method comprises: A) filtering at least one of marking information relating to the marking operation and locate information relating to the locate operation so as to provide filtered information; and B) comparing the marking information to the locate information, wherein at least one of the marking information and the locate information includes the filtered information. 
     Another embodiment is directed to an apparatus for automatically assessing a quality of a locate and/or marking operation. The apparatus comprises: a memory storing processor-executable instructions; at least one I/O interface; and a processor coupled to the memory and the at least one I/O interface. Upon execution of the processor-executable instructions, the processor: A) identifies at least one first geographic location at which at least one facility line of at least one underground facility was marked during the marking operation; B) obtains marking geo-location data based on A); C) identifies at least one first geographic location at which at least one facility line of at least one underground facility was detected during the locate operation; D) obtains locate geo-location data based C); E) filters the locate geo-location data obtained in D); F) determines a measure of distances between the marking geo-location data and the filtered locate geo-location data; G) assesses the quality of the locate and/or marking operation based at least in part on F); and H) generates at least one indication of a quality assessment based on G). 
     For purposes of the present disclosure, the term “dig area” refers to a specified area of a work site within which there is a plan to disturb the ground (e.g., excavate, dig holes and/or trenches, bore, etc.), and beyond which there is no plan to excavate in the immediate surroundings. Thus, the metes and bounds of a dig area are intended to provide specificity as to where some disturbance to the ground is planned at a given work site. It should be appreciated that a given work site may include multiple dig areas. 
     The term “facility” refers to one or more lines, cables, fibers, conduits, transmitters, receivers, or other physical objects or structures capable of or used for carrying, transmitting, receiving, storing, and providing utilities, energy, data, substances, and/or services, and/or any combination thereof. The term “underground facility” means any facility beneath the surface of the ground. Examples of facilities include, but are not limited to, oil, gas, water, sewer, power, telephone, data transmission, cable television (TV), and/or internet services. 
     The term “locate device” refers to any apparatus and/or device, used alone or in combination with any other device, for detecting and/or inferring the presence or absence of any facility, including without limitation, any underground facility. In various examples, a locate device often includes both a locate transmitter and a locate receiver (which in some instances may also be referred to collectively as a “locate instrument set,” or simply “locate set”). 
     The term “marking device” refers to any apparatus, mechanism, or other device that employs a marking dispenser for causing a marking material and/or marking object to be dispensed, or any apparatus, mechanism, or other device for electronically indicating (e.g., logging in memory) a location, such as a location of an underground facility. Additionally, the term “marking dispenser” refers to any apparatus, mechanism, or other device for dispensing and/or otherwise using, separately or in combination, a marking material and/or a marking object. An example of a marking dispenser may include, but is not limited to, a pressurized can of marking paint. The term “marking material” means any material, substance, compound, and/or element, used or which may be used separately or in combination to mark, signify, and/or indicate. Examples of marking materials may include, but are not limited to, paint, chalk, dye, and/or iron. The term “marking object” means any object and/or objects used or which may be used separately or in combination to mark, signify, and/or indicate. Examples of marking objects may include, but are not limited to, a flag, a dart, and arrow, and/or an RFID marking ball. It is contemplated that marking material may include marking objects. It is further contemplated that the terms “marking materials” or “marking objects” may be used interchangeably in accordance with the present disclosure. 
     The term “locate mark” means any mark, sign, and/or object employed to indicate the presence or absence of any underground facility. Examples of locate marks may include, but are not limited to, marks made with marking materials, marking objects, global positioning or other information, and/or any other means. Locate marks may be represented in any form including, without limitation, physical, visible, electronic, and/or any combination thereof. 
     The terms “actuate” or “trigger” (verb form) are used interchangeably to refer to starting or causing any device, program, system, and/or any combination thereof to work, operate, and/or function in response to some type of signal or stimulus. Examples of actuation signals or stimuli may include, but are not limited to, any local or remote, physical, audible, inaudible, visual, non-visual, electronic, mechanical, electromechanical, biomechanical, biosensing or other signal, instruction, or event. The terms “actuator” or “trigger” (noun form) are used interchangeably to refer to any method or device used to generate one or more signals or stimuli to cause or causing actuation. Examples of an actuator/trigger may include, but are not limited to, any form or combination of a lever, switch, program, processor, screen, microphone for capturing audible commands, and/or other device or method. An actuator/trigger may also include, but is not limited to, a device, software, or program that responds to any movement and/or condition of a user, such as, but not limited to, eye movement, brain activity, heart rate, other data, and/or the like, and generates one or more signals or stimuli in response thereto. In the case of a marking device or other marking mechanism (e.g., to physically or electronically mark a facility or other feature), actuation may cause marking material to be dispensed, as well as various data relating to the marking operation (e.g., geographic location, time stamps, characteristics of material dispensed, etc.) to be logged in an electronic file stored in memory. In the case of a locate device or other locate mechanism (e.g., to physically locate a facility or other feature), actuation may cause a detected signal strength, signal frequency, depth, or other information relating to the locate operation to be logged in an electronic file stored in memory. 
     The terms “locate and marking operation,” “locate operation,” and “locate” generally are used interchangeably and refer to any activity to detect, infer, and/or mark the presence or absence of an underground facility. In some contexts, the term “locate operation” is used to more specifically refer to detection of one or more underground facilities, and the term “marking operation” is used to more specifically refer to using a marking device, marking material and/or one or more marking objects to mark a presence or an absence of one or more underground facilities. The term “locate technician” refers to an individual performing a locate operation. A locate and marking operation often is specified in connection with a dig area, at least a portion of which may be excavated or otherwise disturbed during excavation activities. 
     The term “user” refers to an individual utilizing a locate device and/or a marking device and may include, but is not limited to, land surveyors, locate technicians, and support personnel. 
     The terms “locate request” and “excavation notice” are used interchangeably to refer to any communication to request a locate and/or marking operation. The term “locate request ticket” (or simply “ticket”) refers to any communication or instruction to perform a locate operation. A ticket might specify, for example, the address or description of a dig area to be marked, the day and/or time that the dig area is to be marked, and/or whether the user is to mark the excavation area for certain gas, water, sewer, power, telephone, cable television, and/or some other underground facility. The term “historical ticket” refers to past tickets that have been completed. 
     The term “complex event processing (CEP)” refers to a software and/or hardware-implemented (e.g., facilitated by a computer system, distributed computer system, computational analysis coded in software, and/or a combination thereof) technique relating to recognizing one or more events, patterns of events, or the absence of an event or pattern of events, within one or more input streams of information and performing one or more actions and/or computations in response to such recognition, in accordance with specified rules, criteria, algorithms, or logic. CEP generally involves detection of relationships between information contained in input streams (which input streams may include indications of previously recognized events), such as causality, membership, timing, event-driven processes, detection of complex patterns of one or more events, event streams processing, event correlation and abstraction, and/or event hierarchies. CEP may complement and contribute to technologies such as, but not limited to, service oriented architecture (SOA), event driven architecture (EDA), and/or business process management (BPM). CEP allows the information contained in the events flowing through all of the layers of a service business, an enterprise information technology infrastructure and/or management operation to be discovered, analyzed, and understood in terms of its impact on management goals and business processes, and acted upon in real time or as a management process. 
     The following U.S. published application are hereby incorporated herein by reference: 
     U.S. Pat. No. 7,640,105, issued Dec. 29, 2009, filed Mar. 13, 2007, and entitled “Marking System and Method With Location and/or Time Tracking;” 
     U.S. publication no. 2010-0094553-A1, published Apr. 15, 2010, filed Dec. 16, 2009, and entitled “Systems and Methods for Using Location Data and/or Time Data to Electronically Display Dispensing of Markers by A Marking System or Marking Tool;” 
     U.S. publication no. 2008-0245299-A1, published Oct. 9, 2008, filed Apr. 4, 2007, and entitled “Marking System and Method;” 
     U.S. publication no. 2009-0013928-A1, published Jan. 15, 2009, filed Sep. 24, 2008, and entitled “Marking System and Method;” 
     U.S. publication no. 2010-0090858-A1, published Apr. 15, 2010, filed Dec. 16, 2009, and entitled “Systems and Methods for Using Marking Information to Electronically Display Dispensing of Markers by a Marking System or Marking Tool;” 
     U.S. publication no. 2009-0238414-A1, published Sep. 24, 2009, filed Mar. 18, 2008, and entitled “Virtual White Lines for Delimiting Planned Excavation Sites;” 
     U.S. publication no. 2009-0241045-A1, published Sep. 24, 2009, filed Sep. 26, 2008, and entitled “Virtual White Lines for Delimiting Planned Excavation Sites;” 
     U.S. publication no. 2009-0238415-A1, published Sep. 24, 2009, filed Sep. 26, 2008, and entitled “Virtual White Lines for Delimiting Planned Excavation Sites;” 
     U.S. publication no. 2009-0241046-A1, published Sep. 24, 2009, filed Jan. 16, 2009, and entitled “Virtual White Lines for Delimiting Planned Excavation Sites;” 
     U.S. publication no. 2009-0238416-A1, published Sep. 24, 2009, filed Jan. 16, 2009, and entitled “Virtual White Lines for Delimiting Planned Excavation Sites;” 
     U.S. publication no. 2009-0237408-A1, published Sep. 24, 2009, filed Jan. 16, 2009, and entitled “Virtual White Lines for Delimiting Planned Excavation Sites;” 
     U.S. publication no. 2009-0202101-A1, published Aug. 13, 2009, filed Feb. 12, 2008, and entitled “Electronic Manifest of Underground Facility Locate Marks;” 
     U.S. publication no. 2009-0202110-A1, published Aug. 13, 2009, filed Sep. 11, 2008, and entitled “Electronic Manifest of Underground Facility Locate Marks;” 
     U.S. publication no. 2009-0201311-A1, published Aug. 13, 2009, filed Jan. 30, 2009, and entitled “Electronic Manifest of Underground Facility Locate Marks;” 
     U.S. publication no. 2009-0202111-A1, published Aug. 13, 2009, filed Jan. 30, 2009, and entitled “Electronic Manifest of Underground Facility Locate Marks;” 
     U.S. publication no. 2009-0204625-A1, published Aug. 13, 2009, filed Feb. 5, 2009, and entitled “Electronic Manifest of Underground Facility Locate Operation;” 
     U.S. publication no. 2009-0204466-A1, published Aug. 13, 2009, filed Sep. 4, 2008, and entitled “Ticket Approval System For and Method of Performing Quality Control In Field Service Applications;” 
     U.S. publication no. 2009-0207019-A1, published Aug. 20, 2009, filed Apr. 30, 2009, and entitled “Ticket Approval System For and Method of Performing Quality Control In Field Service Applications;” 
     U.S. publication no. 2009-0210284-A1, published Aug. 20, 2009, filed Apr. 30, 2009, and entitled “Ticket Approval System For and Method of Performing Quality Control In Field Service Applications;” 
     U.S. publication no. 2009-0210297-A1, published Aug. 20, 2009, filed Apr. 30, 2009, and entitled “Ticket Approval System For and Method of Performing Quality Control In Field Service Applications;” 
     U.S. publication no. 2009-0210298-A1, published Aug. 20, 2009, filed Apr. 30, 2009, and entitled “Ticket Approval System For and Method of Performing Quality Control In Field Service Applications;” 
     U.S. publication no. 2009-0210285-A1, published Aug. 20, 2009, filed Apr. 30, 2009, and entitled “Ticket Approval System For and Method of Performing Quality Control In Field Service Applications;” 
     U.S. publication no. 2009-0324815-A1, published Dec. 31, 2009, filed Apr. 24, 2009, and entitled “Marking Apparatus and Marking Methods Using Marking Dispenser with Machine-Readable ID Mechanism;” 
     U.S. publication no. 2010-0006667-A1, published Jan. 14, 2010, filed Apr. 24, 2009, and entitled, “Marker Detection Mechanisms for use in Marking Devices And Methods of Using Same;” 
     U.S. publication no. 2010-0085694 A1, published Apr. 8, 2010, filed Sep. 30, 2009, and entitled, “Marking Device Docking Stations and Methods of Using Same;” 
     U.S. publication no. 2010-0085701 A1, published Apr. 8, 2010, filed Sep. 30, 2009, and entitled, “Marking Device Docking Stations Having Security Features and Methods of Using Same;” 
     U.S. publication no. 2010-0084532 A1, published Apr. 8, 2010, filed Sep. 30, 2009, and entitled, “Marking Device Docking Stations Having Mechanical Docking and Methods of Using Same;” 
     U.S. publication no. 2010-0088032-A1, published Apr. 8, 2010, filed Sep. 29, 2009, and entitled, “Methods, Apparatus and Systems for Generating Electronic Records of Locate And Marking Operations, and Combined Locate and Marking Apparatus for Same;” 
     U.S. publication no. 2010-0117654 A1, published May 13, 2010, filed Dec. 30, 2009, and entitled, “Methods and Apparatus for Displaying an Electronic Rendering of a Locate and/or Marking Operation Using Display Layers;” 
     U.S. publication no. 2010-0086677 A1, published Apr. 8, 2010, filed Aug. 11, 2009, and entitled, “Methods and Apparatus for Generating an Electronic Record of a Marking Operation Including Service-Related Information and Ticket Information;” 
     U.S. publication no. 2010-0086671 A1, published Apr. 8, 2010, filed Nov. 20, 2009, and entitled, “Methods and Apparatus for Generating an Electronic Record of A Marking Operation Including Service-Related Information and Ticket Information;” 
     U.S. publication no. 2010-0085376 A1, published Apr. 8, 2010, filed Oct. 28, 2009,and entitled, “Methods and Apparatus for Displaying an Electronic Rendering of a Marking Operation Based on an Electronic Record of Marking Information;” 
     U.S. publication no. 2010-0088164-A1, published Apr. 8, 2010, filed Sep. 30, 2009, and entitled, “Methods and Apparatus for Analyzing Locate and Marking Operations with Respect to Facilities Maps;” 
     U.S. publication no. 2010-0088134 A1, published Apr. 8, 2010, filed Oct. 1, 2009, and entitled, “Methods and Apparatus for Analyzing Locate and Marking Operations with Respect to Historical Information;” 
     U.S. publication no. 2010-0088031 A1, published Apr. 8, 2010, filed Sep. 28, 2009, and entitled, “Methods and Apparatus for Generating an Electronic Record of Environmental Landmarks Based on Marking Device Actuations;” 
     U.S. publication no. 2010-0188407 A1, published Jul. 29, 2010, filed Feb. 5, 2010, and entitled “Methods and Apparatus for Displaying and Processing Facilities Map Information and/or Other Image Information on a Marking Device;” 
     U.S. publication no. 2010-0188215 A1, published Jul. 29, 2010, filed Feb. 5, 2010, and entitled “Methods and Apparatus for Generating Alerts on a Marking Device, Based on Comparing Electronic Marking Information to Facilities Map Information and/or Other Image Information;” 
     U.S. publication no. 2010-0188088 A1, published Jul. 29, 2010, filed Feb. 5, 2010, and entitled “Methods and Apparatus for Displaying and Processing Facilities Map Information and/or Other Image Information on a Locate Device;” 
     U.S. publication no. 2010-0189312 A1, published Jul. 29, 2010, filed Feb. 5, 2010, and entitled “Methods and Apparatus for Overlaying Electronic Locate Information on Facilities Map Information and/or Other Image Information Displayed on a Locate Device;” 
     U.S. publication no. 2010-0188216 A1, published Jul. 29, 2010, filed Feb. 5, 2010, and entitled “Methods and Apparatus for Generating Alerts on a Locate Device, Based ON Comparing Electronic Locate Information TO Facilities Map Information and/or Other Image Information;” 
     U.S. publication no. 2010-0189887 A1, published Jul. 29, 2010, filed Feb. 11, 2010, and entitled “Marking Apparatus Having Enhanced Features for Underground Facility Marking Operations, and Associated Methods and Systems;” 
     U.S. publication no. 2010-0188245 A1, published Jul. 29, 2010, filed Feb. 11, 2010, and entitled “Locate Apparatus Having Enhanced Features for Underground Facility Locate Operations, and Associated Methods and Systems;” 
     U.S. publication no. 2009-0204238-A1, published Aug. 13, 2009, filed Feb. 2, 2009, and entitled “Electronically Controlled Marking Apparatus and Methods;” 
     U.S. publication no. 2009-0208642-A1, published Aug. 20, 2009, filed Feb. 2, 2009, and entitled “Marking Apparatus and Methods For Creating an Electronic Record of Marking Operations;” 
     U.S. publication no. 2009-0210098-A1, published Aug. 20, 2009, filed Feb. 2, 2009, and entitled “Marking Apparatus and Methods For Creating an Electronic Record of Marking Apparatus Operations;” 
     U.S. publication no. 2009-0201178-A1, published Aug. 13, 2009, filed Feb. 2, 2009, and entitled “Methods For Evaluating Operation of Marking Apparatus;” 
     U.S. publication no. 2009-0238417-A1, published Sep. 24, 2009, filed Feb. 6, 2009, and entitled “Virtual White Lines for Indicating Planned Excavation Sites on Electronic Images;” 
     U.S. publication no. 2009-0202112-A1, published Aug. 13, 2009, filed Feb. 11, 2009, and entitled “Searchable Electronic Records of Underground Facility Locate Marking Operations;” 
     U.S. publication no. 2009-0204614-A1, published Aug. 13, 2009, filed Feb. 11, 2009, and entitled “Searchable Electronic Records of Underground Facility Locate Marking Operations;” 
     U.S. publication no. 2009-0327024-A1, published Dec. 31, 2009, filed Jun. 26, 2009, and entitled “Methods and Apparatus for Quality Assessment of a Field Service Operation;” 
     U.S. publication no. 2010-0010862-A1, published Jan. 14, 2010, filed Aug. 7, 2009, and entitled, “Methods and Apparatus for Quality Assessment of a Field Service Operation Based on Geographic Information;” 
     U.S. publication No. 2010-0010863-A1, published Jan. 14, 2010, filed Aug. 7, 2009, and entitled, “Methods and Apparatus for Quality Assessment of a Field Service Operation Based on Multiple Scoring Categories;” 
     U.S. publication no. 2010-0010882-A1, published Jan. 14, 2010, filed Aug. 7, 2009, and entitled, “Methods and Apparatus for Quality Assessment of a Field Service Operation Based on Dynamic Assessment Parameters;” 
     U.S. publication no. 2010-0010883-A1, published Jan. 14, 2010, filed Aug. 7, 2009, and entitled, “Methods and Apparatus for Quality Assessment of a Field Service Operation Based on Multiple Quality Assessment Criteria;” 
     U.S. publication no. 2010-0088135 A1, published Apr. 8, 2010, filed Oct. 1, 2009, and entitled, “Methods and Apparatus for Analyzing Locate and Marking Operations with Respect to Environmental Landmarks;” 
     U.S. publication no. 2010-0085185 A1, published Apr. 8, 2010, filed Sep. 30, 2009, and entitled, “Methods and Apparatus for Generating Electronic Records of Locate Operations;” 
     U.S. publication no. 2010-0090700-A1, published Apr. 15, 2010, filed Oct. 30, 2009, and entitled “Methods and Apparatus for Displaying an Electronic Rendering of a Locate Operation Based on an Electronic Record of Locate Information;” and 
     U.S. publication no. 2010-0085054 A1, published Apr. 8, 2010, filed Sep. 30, 2009, and entitled, “Systems and Methods for Generating Electronic Records of Locate And Marking Operations.” 
     It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. It should also be appreciated that terminology explicitly employed herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. 
         FIG. 1  shows an example in which a locate and marking operation is initiated as a result of an excavator providing an excavation notice to a one-call center. 
         FIG. 2  illustrates a block diagram of an automated quality assessment system for assessing the quality of a field service operation, in accordance with some embodiments of the present disclosure. 
         FIG. 3  illustrates a flow diagram of an example of a process for automatically assessing the quality of a field service operation, in accordance with some embodiments of the present disclosure. 
         FIG. 4  illustrates a functional block diagram of an example of an automated quality assessment application and various data sources for automatically performing quality control in connection with underground facility locate and/or marking operations, in accordance with some embodiments of the present disclosure. 
         FIG. 5  illustrates an electronic manifest comprising both image data and non-image data relating to a locate and/or marking operation, in accordance with some embodiments of the present disclosure. 
         FIG. 6  illustrates a data set that may be associated with an electronic manifest from which information may be obtained for a quality assessment, in accordance with some embodiments of the present disclosure. 
         FIG. 7  is an example of a facilities map from which information may be obtained for a quality assessment, in accordance with some embodiments of the present disclosure. 
         FIG. 8  illustrates a flow diagram of an exemplary method for automatically performing a quality assessment regarding an underground facility locate and/or marking operation using the automated quality assessment system shown in  FIG. 2 , in accordance with some embodiments of the present disclosure. 
         FIG. 9  illustrates a flow diagram of an exemplary method for performing a quality assessment based on a comparison of marking information and locate information, in accordance with some embodiments of the present disclosure. 
         FIG. 10  illustrates flow diagram outlining a process for determining a distance between two sets of geographical points, in accordance with some embodiments of the present disclosure. 
         FIG. 11  illustrates exemplary sets of geographical data points for comparison respectively corresponding to a locate operation and an associated marking operation, in accordance with some embodiments of the present invention. 
         FIG. 12  is an example of a computer-aided visual rendering illustrating an overlay of marking information and locate information, in accordance with some embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Following below are more detailed descriptions of various concepts related to, and embodiments of, inventive systems, methods and apparatus for analyzing and assessing the quality of locate and/or marking operations. It should be appreciated that various concepts introduced above and discussed in greater detail below may be implemented in any of numerous ways, as the disclosed concepts are not limited to any particular manner of implementation. Examples of specific implementations and applications are provided primarily for illustrative purposes. 
     I. Overview 
     Various inventive embodiments disclosed herein relate to methods, apparatus and systems for performing oversight and quality control in field service operations, such as locate and marking operations. In general, approvers and/or managers may review the quality of these locate and marking operations in real time and/or within a certain amount of time (e.g., within one day) of completion of the operation. The review of a locate and marking operation by a human (e.g., an approver or manager) and the determination of a quality assessment for the operation based solely on the discretion of the human is referred to herein as a “manual quality assessment.” 
     Some embodiments described herein are related to methods, apparatus and systems for at least partially automating oversight and quality assessment in underground facility locate and marking operations and/or other field service operations. For example, in some embodiments, an automated quality assessment system may receive “field information” (also referred to as “field data”) related to a locate and/or marking operation from one or more sources of electronic data (e.g., electronic records of locate and/or marking operations generated by various locate equipment, an electronic manifest for same, ticket information, service-related information, etc.), electronically analyze the contents of the field information/data by comparing locate and/or marking information (e.g., locate device data, marking device data) to “reference information” (also referred to as “reference data”), and automatically assess the quality of the operation based at least in part on the analysis (e.g., according to predetermined criteria on which the comparison is based and metrics for the criteria). 
     In some embodiments, the reference information itself may include field information; for example, in some implementations, different types of field information may be compared to each other. In one example, first field information relating to a marking operation (“marking information”) may be compared with reference information in the form of second field information relating to a locate operation (“locate information”). It should be appreciated that in embodiments in which different types of field information are compared with each other, the distinction between “field information” and “reference information” may not have any practical effect; however, for various reasons, in some implementations it may be desirable to designate one type of the field information as the “reference information” for purposes of comparison (e.g., it may be presumed a priori that a first type of field information is generally more reliable than a second type of field information, and that hence the first type of field information is taken as the “reference information” for purposes of comparative analysis). Accordingly, in examples of these embodiments, either one of the marking information and locate information may serve as the reference information in various scenarios. 
     In other embodiments, automated analysis of field information/data facilitates further analysis and/or quality assessment by a human, in which the quality assessment is not based solely on the discretion of the human, but is significantly informed in some manner by automated analysis of data. As contrasted with the above-discussed “manual quality assessment” of a locate and marking operation by a human, this type of assessment (e.g., based on some degree of electronic analysis of data relating to a locate and/or marking operation) is referred to herein as “automated quality assessment.” 
     In some embodiments, methods, apparatus and systems according to the present invention may automatically output one or more of a variety of indications of the assessed quality of a locate and/or marking operation. In one aspect, the indication of the assessed quality of a locate and/or marking operation may be categorized into one or more of a plurality of quality categories. Any suitable number and type of categories may be used, as the invention is not limited in this respect. For example, in some embodiments, a locate and/or marking operation may be automatically categorized as either, (a) approved—no further action needed; (b) satisfactory, but the locate technician needs coaching or training; (c) unsatisfactory—the ticket needs quality control (QC) action; or (d) real-time prompt—an aspect of the assessment may be suitable for prompting the locate technician in real time with respect to, for example, performing an immediate verification and/or corrective action. In other implementations, a score, grade, or other graduated indication (e.g., based on some maximum range or scale) may be provided as an indication of quality assessment in connection with a locate and/or marking operation. 
     II. Automated Quality Assessment 
       FIG. 2  is a block diagram of an automated quality assessment system  1800 . Automated quality assessment system  1800  may be, for example, a computer system having at least one hardware processor  1803 , a memory  1805  that comprises at least one tangible storage medium (e.g., RAM, ROM, Flash memory, one or more magnetic storage devices, one or more optical storage devices, or any other type of tangible storage medium), and at least one communications interface  1801 . Memory  1805  may store computer-readable (processor-executable) instructions of an automated quality assessment application  1200 , which may be executed by processor  1803 . When executed by processor  1803 , automated quality assessment application  1200  may obtain information associated with a field service operation (e.g., a locate and/or marking operation) from data sources  1216  via communication interface  1801 , analyze the data to assess the quality of the field service operation and may output (e.g., via communication interface  1801 ) one or more indications of the quality assessment of the field service operation. In some implementations, one or more indications of the quality assessment may be stored in the memory and/or transmitted via the communication interface to provide an electronic record of the quality assessment. The communication interface  1801  may be coupled to a wired or wireless network, bus, or other communication means and may therefore allow the system  1800  to transmit communications to and/or receive communications from other devices. 
     The computer system of  FIG. 2  serving as an automated quality assessment system  1800  may further comprise one or more user interfaces  1802 , which may include one or more display units (not shown) The display unit(s) may be provided, for example, to allow a user to view various information in connection with execution of the instructions and/or the indication(s) of quality assessment. In general, the user interface allows a user to communicate with the processor  1803 , make manual adjustments, make selections, enter data or various other information, receive information, and/or interact in any of a variety of manners with the processor during execution of the instructions. 
       FIG. 3  is a flow chart of process  1900  that may be performed by quality assessment application  1200  to automatically assess the quality of a field service operation, such as, for example, a locate and/or marking operation. Process  1900  begins at act  1901 , where the automated quality assessment application receives electronic information associated with a field service operation. The process next continues to act  1903 , where the automated quality assessment application analyzes at least some of the received information to automatically generate a quality assessment of the field service operation. The process next continues to act  1905 , where the automated quality assessment application outputs an indication of the quality of the field service operation that is based on the assessment generated in the act  1903 . 
     Referring to  FIG. 4 , a more detailed block diagram of automated quality assessment application  1200  and data sources  1216  is presented. Automated quality assessment application  1200  may be, for example, a rules-based computer software application that includes, for example, an information processing component  1210 , quality assessment outcomes  1212  (e.g., one or more indications of the quality assessment), and a feedback component  1214 . Automated quality assessment application  1200  may be fed by any number of data sources  1216 , which may include various types of electronic information and/or records of data associated with locate and/or marking operations performed in the field (e.g., both “field information/data” and “reference information/data”). 
     For example, the automated quality assessment application  1200  of the present disclosure may automatically review a variety of field information, which may include “closed” or completed tickets (i.e., tickets pursuant to which a locate and/or marking operation has been performed) and their associated manifests (which may or may not include digital images relating to the locate operation), and/or any information relating thereto, in essentially real time and/or within a specified amount of time, such as within one day, from the ticket being closed. In some embodiments discussed in further detail below, closed tickets may be reviewed by automatically interrogating received data associated with a locate and/or marking operation, and comparing selected received data against various metrics, such as reference information/data. 
     In some embodiments, information processing component  1210  of automated quality assessment application  1200  may be, for example, a rules-based software component for analyzing the contents of any information that is available in data sources  1216  and then automatically performing an assessment with respect to the quality of a locate and/or marking operation that is performed in the field. For each locate and/or marking operation that is assessed, information processing component  1210  may automatically generate a quality assessment outcome  1212  that corresponds to the results of the automatic quality assessment. 
     Any suitable type of outcome may be generated. For example, in some embodiments, the outcome generated may be a categorization of the locate operation into one of a plurality of quality categories (also referred to herein as “scoring” categories or “grading” categories). For example, based on the automatic quality assessment, a locate and/or marking operation may be categorized as:
         APPROVED—the locate and/or marking operation is approved, no further action needed;   SATISFACTORY—the locate and/or marking operation is approved, but the locate technician needs coaching or training;   UNSATISFACTORY—the locate and/or marking operation is not approved, the ticket needs QC action; or   PROMPT—an aspect of the locate and/or marking operation assessment may be suitable for transmitting a real-time prompt to the locate technician with respect to, for example, performing a substantially immediate verification and/or corrective action.       

     Other examples of possible outcomes generated by automated ticket application 1200 include, but are not limited to, a numerical score (e.g., a score of 0-100%), a grade (e.g., a grade of A-F), or other graduated indicator, based on some range, scale and/or resolution (granularity), that is indicative of the quality of the assessed locate operation. 
     Feedback component  1214  of automated quality assessment application  1200  generates the real-time prompts. For example, once the nature of the real-time prompt is determined, feedback component  1214  queries the ticket information in order to ensure that the prompt is directed to the proper originating locate technician. Additional details of the operation of automated quality assessment application  1200  are described with reference to the method of  FIG. 6 . 
     III. Exemplary Data Sources for Use in Quality Assessment 
     Examples of data sources  1216  that may be processed by information processing component  1210  of automated quality assessment application  100  may include, but are not limited to, one or more tickets  1220 , a virtual white lines (VWL) application  1230 , a ticket assessment application  1240 , locating equipment data  1250 , an electronic manifest (EM) application  1260 , one or more facilities maps  1280 , an archive of historical tickets  1290 , and any other electronic information and/or records  1295 . In exemplary implementations, the various data sources  1216  may be supplied by multiple entities (not shown) and accessible to automated quality assessment application  1200  via, for example, a networked computing system for supporting locate and/or marking operations, an example of which is depicted in  FIG. 1 . 
     In various embodiments of automated quality assessment based on information/data derived from the data sources  1216 , it should be appreciated that some of this information/data may be treated as “field information/data” and some of this information/data may be treated as “reference information/data” to which the field information/data is compared during the assessment process. Additionally, it should be appreciated that some of the information/data available from the data sources  1216  may be used to “pre-process” or filter one or both of the field information/data and the reference information/data prior to comparison for some types of assessments. 
     A. Tickets 
     Tickets  1220  of data sources  1216  are locate request tickets that may be submitted by excavators and processed by one-call centers. Tickets  1220  may include textual ticket information  1222  that comprises instructions with respect to performing a locate and/or marking operation, such as, but not limited to, a ticket and/or work order number, date information, geographic location information (e.g., address information), excavation information, excavator information, site information (e.g., a description of the dig area, which may include a description of one or more environmental landmarks in or near the dig area/work site), locate operations instructions information, caller information, remarks information, task information, and any combinations thereof. 
     Historical tickets  1290  of data sources  1216  may include any records of prior locate and/or marking operations performed pursuant to previous locate request tickets. These historical records may relate in some instances, but not necessarily, to locate and/or marking operations performed in the past for the same work site/dig area specified in the present ticket  1220  subject to quality assessment. In the process of performing the automatic quality assessment of a present ticket  1220 , information processing component  1210  may aggregate the information that is contained in one or more historical tickets  1290  (which in some cases may relate to the same work site/dig area) in order to determine the facilities that have been located and/or marked during past locate operations at that site, and/or the presence of one or more environmental landmarks. Some of the information types discussed in further detail below may form part of a historical ticket and may be derived from records associated with such tickets for purposes of an assessment. For example, records associated with historical tickets may include digital images having one or more of dig area indicators, electronic locate marks and symbols or icons for environmental landmarks overlaid thereon; additionally, or alternatively, such records may include a variety of data provided by one or more pieces of locating and/or marking equipment used to perform the locate and/or marking operation (see sections B, C, and D below). 
     B. Dig Area Indicators and Associated Information 
     VWL application  1230  of data sources  1216  is a computer software application that provides an electronic drawing tool that may be used by excavators for electronically marking up, for example, a digital aerial image of the dig area. In this manner, instead of (or in addition to) physically visiting the site of the dig area and marking white lines on the ground at that site, an excavator may electronically draw markings (e.g., white lines) on an aerial image of the site, indicating where digging is planned. These marked up digital images may be saved as, for example, VWL images  1232 , which may include accompanied with metadata pertaining to various information in the images. One or more VWL images  1232  in turn may be associated with, for example, tickets  1220  and transmitted to locate companies. 
     VWL application  1230  may be implemented, for example, as described in U.S. patent application Ser. No. 12/366,853 filed Feb. 6, 2009, entitled “Virtual white lines for delimiting planned excavation sites;” U.S. patent application Ser. No. 12/475,905 filed Jun. 1, 2009, entitled “Virtual white lines for delimiting planned excavation sites of staged excavation projects;” U.S. patent application Ser. No. 12/422,364 filed Apr. 13, 2009, entitled “Virtual white lines (VWL) application for indicating a planned excavation or locate path.” Each of these patent applications is hereby incorporated by reference herein in its entirety. 
     In one example, the dig area indicators in a VWL image may include two-dimensional (2D) drawing shapes, shades, points, symbols, coordinates, data sets, or other indicators to indicate on a digital image the dig area in which excavation is to occur. To generate the electronic image having dig area indicators, an image (e.g., an aerial image) of the work site may be sent to an excavator via a network, the excavator may use a computing device executing the VWL application  1230  to create a VWL image by marking up the image to include one or more dig area indicators precisely delimiting one or more dig areas within the work site and, in response, the marked-up VWL image may be received from the excavator via the network. 
     As noted above, a VWL image  1232  may include metadata corresponding to any markings or content in the image; in particular, geographic information including geographic coordinates (e.g., latitude and longitude values) for any dig area indicators marked on the image may accompany or be included in an image file as metadata, and these geographic coordinates may be employed in some manner as part of a quality assessment process. For example, as discussed further below, in one embodiment geographic information derived from a virtual white lines (VWL) application  1230  (e.g., geographic coordinates associated with one or more dig area indicators contained in a VLW image  1232 ) may be used by automated quality assessment application  1200  to filter or limit the contents of either field data or reference data prior to analysis/comparison of data for quality assessment. 
     In particular, in one exemplary implementation, geographic coordinates associated with a dig area indicator may be used to select contents that relate only to a geographic area including the geographic coordinates for the dig area indicator, or contents that fall within a predetermined radius of the geographic coordinates for the dig area indicator or a polygon-shaped buffer zone around the geographic coordinates for the dig area indicator. In yet another example, geographic coordinates associated with a dig area indicator may be used to filter out some contents that do not relate to a specifically delimited dig area within a work site as defined by the VWL application (e.g., first geographic information or another portion of information may be selected from the field data, and/or second geographic information or another portion of information may be selected from the reference data, that relates only to a geographic area delimited by the VWL geographic information). Accordingly, it should be appreciated that in some embodiments, the dig area indicator coordinates may identify a plurality of points along a perimeter of the delimited dig area, and these coordinates may be used to select specific geographic information (e.g., filter out geographic information outside of the delimited dig area). In other embodiments, the dig area indicator coordinates may identify a single point, in which case the coordinates may be used to select particular information based at least in part on the coordinates for the single point. 
     C. Locating Equipment Data 
     With respect to locating equipment data  1250 , as noted above, a locate technician may use locating equipment, such as a locate instrument set (including a locate receiver device), a marking device, or a combined locate and marking device, so as to perform a locate and marking operation. Locating equipment data  1250  of data sources  1216  may be any information that is collected and/or generated (e.g., one or more electronic records) by any type of locating and/or marking equipment equipped with components that are capable of collecting electronic information and/or creating electronic records about locate and/or marking operations that are performed in the field. 
     In some examples, locating equipment data  1250  is constituted by “marking information” or marking device data  1252  that is associated generally with the marking functionality of a locate and marking operation. Examples of marking information relating to a marking operation that may be logged into an electronic record may include, but are not limited to:
         timing information (e.g., one or more time stamps) associated with one or more actuations of the marking device and/or one or more events occurring during a given actuation;   geographic information (e.g., one or more geographic coordinates) associated with one or more actuations of the marking device (in some instances, the geographic information may be accompanied by timing information, such as a time stamp, for each acquisition of geographic information); and/or geographic diagnostics information (e.g., GPS diagnostics information, such as, but not limited to, the quality of a GPS signal, the number of satellites in view of the GPS receiver, etc.);   marking material information: one or more aspects/characteristics of a marking material (e.g., a color, brand, type, serial number, UPC code, weight, inventory information, etc. associated with the marking material) dispensed in response to one or more actuations of the marking device;   service-related information: one or more identifiers for the locate technician performing the marking operation, the marking device itself (e.g., a serial number of the marking device), and/or the locate contractor dispatching the locate technician;   ticket information: information relating to one or more facilities to be marked, location information (e.g., an address, geo-coordinates, and/or text description) relating to the work site and/or dig area in which the locate and marking operation is performed, ground type information (e.g., a description of the ground at which marking material is dispensed), excavator information, other text-based information, etc.;   environmental information: information derived from one or more environmental sensors associated with the marking device, examples of which sensors include, but are not limited to, temperature sensors, humidity sensors, light sensors, altitude sensors, image capture devices and audio recorders;   operational information: information derived from one or more operational sensors associated with the marking device, examples of which sensors include, but are not limited to, operational temperature sensors, a compass, an inclinometer, an accelerometer, a yaw rate sensor, a proximity sensor, a pressure sensor, one or more device health sensors, image capture devices, and audio devices; and   device health information: information about the status of one or more components of a locate device, such as battery status, WiFi connectivity status, GPS receiver status (e.g., GPS signal strength/quality, number of satellites in view), etc.       

     Marking information including any or all of the foregoing types of information may be logged/stored in local memory of a marking device, formatted in various manners, processed and/or analyzed at the marking device itself, and/or transmitted to another device (e.g., a remote computer/server) for storage, processing and/or analysis. 
     Similarly, locating equipment data  1250  may include “locate information” or locate receiver data  1254  that is associated generally with the locating/detection functionality of a locate and marking operation. Examples of locate information relating to the locate operation that may be logged into an electronic record may include, but are not limited to, any of the following types of information or any suitable combinations of such information:
         timing information (e.g., one or more time stamps) associated with one or more events occurring during a given locate operation;   geographic information (e.g., one or more geographic coordinates) associated with one or more events of a locate operation (in some instances, the geographic information may be accompanied by timing information, such as a time stamp, for each acquisition of geographic information); and/or geographic diagnostics information (e.g., GPS diagnostics information, such as, but not limited to, the quality of a GPS signal, the number of satellites in view of the GPS receiver, etc.);   service-related information: one or more identifiers for the locate technician performing the locate operation, the locate contractor (service provider) dispatching the locate technician, and/or the party requesting the locate operation;   ticket information: information relating to one or more facilities to be located, location information (e.g., an address, geo-coordinates, and/or text description) relating to the work site and/or dig area in which the locate and marking operation is performed, ground type information (e.g., a description of the ground at which the locate is performed), excavator information, other text-based information, etc.   target object information: information about the target object (e.g., facility) to be located, such as the type of object, expected depth of object, etc.;   locate signal information: information entered, detected and/or sensed as part of performing the locate operation relating to one or more signals representing a presence or absence of one or more underground facilities, such as magnetic field strength and frequency, electric current magnitude, depth of the located object, the mode of operation of the locate receiver (e.g., peak v. null detection modes), the gain of the locate receiver, etc. With respect to locate receivers, the “gain” is typically a measure of the degree of sensitivity of a locate receiver antenna that is picking up a signal emanating from along an underground facility (alternatively, “gain” may be viewed as a degree of amplification being applied to a received signal). Gain may be expressed in terms of any scale (e.g., 0-100), as a numeric value or percentage. “Signal strength” (or “magnetic field strength”) refers to the strength of a received signal at a given gain value; signal strength similarly may be expressed in terms of any scale, as a numeric value or percentage. Generally speaking, higher signal strengths at lower gains typically indicate more reliable information from a locate receiver, but this may not necessarily be the case for all locate operations;   locate receiver information: information about the locate receiver, such as identification of the locate receiver (e.g., serial number), make and model of the locate receiver, mode of operation (e.g., passive or active, and peak or null), battery level, etc.;   transmitter information: information about any transmitter and transmitter signal (also referred to herein as an applied signal) utilized for the locate operation, such as transmitter type, identification of the transmitter (e.g., serial number), make and model of the transmitter, mode of operation (e.g., inductive and conductive), battery level, connection type, electrical ground type, electrical ground position, moisture content of physical ground to which electrical ground contact is made, pH of physical ground, applied signal frequency, available signal frequencies, transmitter power, whether a continuity indication is provided for the applied signal, etc.;   tracer wire information: information about a tracer wire provided along the underground facility, such as tracer wire material (e.g., aluminum, tin/steel, copper/stainless steel, etc.), gauge of the tracer wire, condition of the tracer wire (e.g., whether intact, broken, corroded, etc.), etc.;   environmental information: information derived from one or more environmental sensors associated with the locate device, examples of which sensors include, but are not limited to, temperature sensors, humidity sensors, light sensors, altitude sensors, image capture devices and audio recorders, as well as information that may be manually entered (e.g., by a technician) relating to environmental conditions (e.g., ground type in the area of the locate operation, which could also or alternatively be indicated in ticket information);   operational information: information derived from one or more operational sensors associated with the locate device, examples of which sensors include, but are not limited to, operational temperature sensors, a compass, an inclinometer, one or more accelerometers, a yaw rate sensor, a proximity sensor, a pressure sensor, one or more device health sensors, image capture devices, and audio devices; and   Device health information: information about the status of one or more components of a locate device, such as battery status, WiFi connectivity status, GPS receiver status (e.g., GPS signal strength/quality, number of satellites in view), etc.       

     Locate information including any or all of the foregoing types of information may be logged/stored in local memory of a locate device, formatted in various manners, processed and/or analyzed at the locate device itself, and/or transmitted to another device (e.g., a remote computer/server) for storage, processing and/or analysis. 
     Locating equipment data  1250  also may include “landmark information” that may be acquired by suitably configured locating equipment (e.g., a marking device, a locate device, or a combined locate and marking device capable of operating in a “landmark mode”), which information may be acquired either independently or as part of (e.g., during or proximate in time to) a locate and/or marking operation. 
     In one example, marking device data  1252  of locating equipment data  1250  may be electronic information and/or one or more electronic records of data that is provided by electronic marking devices and/or marking systems. Examples of electronic marking devices and/or marking systems that may provide marking device data  1252  may include, but are not limited, to those described in reference to U.S. patent application Ser. No. 11/696,606, filed Apr. 4, 2007 and published Oct. 9, 2008, entitled “Marking system and method;” U.S. patent application Ser. No. 11/685,602, filed Mar. 13, 2007 and published Sep. 18, 2008, entitled “Marking system and method;” U.S. Non-provisional application Ser. No. 12/568,087, filed on September 28, entitled “Methods and Apparatus for Generating an Electronic Record of Environmental Landmarks Based on Marking Device Actuations;” U.S. Non-provisional application Ser. No. 12/539,497, filed on Aug. 11, 2009, entitled “Methods and Apparatus for Generating an Electronic Record of a Marking Operation based on Marking Device Actuations;” U.S. Provisional Patent Application Ser. No. 61/102,151 filed Oct. 2, 2008, entitled “Data acquisition system for and methods of analyzing locate activities based on marking device actuations;” and U.S. Non-provisional patent application Ser. No. 12/703,958, entitled “Marking Apparatus Having Enhanced Features for Underground Facility Marking Operations, and Associated Methods and Systems,” filed Feb. 11, 2010. Each of these applications is incorporated herein by reference in its entirety. 
     Table 1 shows one example of a sample of marking device data  1252  of locating equipment data  1250  that may be captured as the result of, for example, an actuation of a marking device. In some exemplary implementations, an electronic record of a marking operation may include multiple data entries as shown in the example of Table 1 for respective actuations of a marking device to dispense a marking material (e.g., in some cases there may be one set of data as shown in Table 1 for each actuation). In this manner, each time a marker is dispensed (so as to indicate a presence or absence of a given underground facility), data is collected relating to the geographic location of the dispensed marker (e.g., geo-location data). Additionally, data relating to a characteristic of the dispensed marker (e.g., color and/or brand) may be included in the data entries of the electronic record, as well as other data germane to the marking operation. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Example marking device data 1252 
               
               
                 of locating equipment data 1250 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Service provider ID 
                 0482 
               
               
                   
                 Locate technician ID 
                 4815 
               
               
                   
                 Marking Device ID 
                 7362 
               
               
                   
                 Timestamp data 
                 12-Jul-2008; 09:35:15.2 
               
               
                   
                 Geo-location data 
                 N35°43.57518, W078°49.78314 
               
               
                   
                   
                 (deg. and dec. min.) 
               
               
                   
                 Marking material data 
                 Color = Red, Brand = ABC 
               
               
                   
                 Temperature data 
                 73 degrees F. 
               
               
                   
                 Humidity data 
                 30% 
               
               
                   
                 Light data 
                 4.3 volts 
               
               
                   
                 Compass data 
                 213 degrees 
               
               
                   
                 Inclinometer data 
                 −40 
               
               
                   
                 Accelerometer data 
                 0.275 g 
               
               
                   
                 Battery strength data 
                 73% 
               
               
                   
                   
               
            
           
         
       
     
     Table 2 below shows another example of marking device data  1252  of locating equipment data  1250  that may be captured as the result of, for example, one or more actuations of a marking device. Specifically, Table 2 illustrates multiple “actuation data sets” of an electronic record of a marking operation as generated by a marking device, in which each actuation data set includes information associated with multiple actuation event entries logged during a corresponding actuation and dispensing of a locate mark. Table 2 shows three actuation data sets of an electronic record, corresponding to three actuations of the marking device (e.g., act-1, act-2, and act-3). As may be appreciated from the information shown in Table 2, multiple pieces of geo-location data are logged for each actuation of a marking device (in addition to various other information). 
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
             
            
               
                 Example actuation data set for act-1 
               
               
                   
               
            
           
           
               
               
               
            
               
                 act-1 
                 Service 
                 0482 
               
               
                   
                 provider ID 
               
               
                   
                 User ID 
                 4815 
               
               
                   
                 Device ID 
                 7362 
               
               
                   
                 T1 timestamp data 
                 12-Jul-2008; 09:35:15.2 
               
               
                   
                 T2 timestamp data 
                 12-Jul-2008; 09:35:16.1 
               
               
                   
                 Duration (Δt) 
                 00:00:00.9 
               
               
                   
                 T1 geo-location 
                 2650.9348, N, 08003.5057, W 
               
               
                   
                 data 
               
               
                   
                 1 st  interval 
                 2650.9353, N, 08003.5055, W 
               
               
                   
                 location data 
               
               
                   
                 2 nd  interval 
                 2650.9356, N, 08003.5055, W 
               
               
                   
                 location data 
               
               
                   
                 . 
                 . 
               
               
                   
                 . 
                 . 
               
               
                   
                 . 
                 . 
               
               
                   
                 Nth interval 
                 2650.9246, N, 08003.5240, W 
               
               
                   
                 location data 
               
               
                   
                 T2 geo-location 
                 2650.9255, N, 08003.5236, W 
               
               
                   
                 data 
               
               
                   
                 Product data 
                 Color = Red, Brand = ABC, 
               
               
                   
                   
                 Type/Batch = 224B-1 
               
               
                   
                 Locate request 
                 Requestor: XYZ Construction Company, 
               
               
                   
                 data 
                 Requested service address: 
               
               
                   
                   
                 222 Main St, Orlando, FL 
               
               
                   
               
            
           
           
               
            
               
                 Example actuation data set for act-2 
               
               
                   
               
            
           
           
               
               
               
            
               
                 act-2 
                 Service 
                 0482 
               
               
                   
                 provider ID 
               
               
                   
                 User ID 
                 4815 
               
               
                   
                 Device ID 
                 7362 
               
               
                   
                 T1 timestamp data 
                 12-Jul-2008; 09:35:17.5 
               
               
                   
                 T2 timestamp data 
                 12-Jul-2008; 09:35:18.7 
               
               
                   
                 Duration (Δt) 
                 00:00:01.2 
               
               
                   
                 T1 geo-location 
                 2650.9256, N, 08003.5234, W 
               
               
                   
                 data 
               
               
                   
                 1st interval 
                 2650.9256, N, 08003.5226, W 
               
               
                   
                 location data 
               
               
                   
                 2 nd  interval 
                 2650.9256, N, 08003.5217, W 
               
               
                   
                 location data 
               
               
                   
                 . 
                 . 
               
               
                   
                 . 
                 . 
               
               
                   
                 . 
                 . 
               
               
                   
                 Nth interval 
                 2650.9260, N, 08003.5199, W 
               
               
                   
                 location data 
               
               
                   
                 T2 geo-location 
                 2650.9266, N, 08003.5196, W 
               
               
                   
                 data 
               
               
                   
                 Product data 
                 Color = Red, Brand = ABC, 
               
               
                   
                   
                 Type/Batch = 224B-1 
               
               
                   
                 Locate request 
                 Requestor: XYZ Construction Company, 
               
               
                   
                 data 
                 Requested service address: 
               
               
                   
                   
                 222 Main St, Orlando, FL 
               
               
                   
               
            
           
           
               
            
               
                 Example actuation data set for act-3 
               
               
                   
               
            
           
           
               
               
               
            
               
                 act-3 
                 Service 
                 0482 
               
               
                   
                 provider ID 
               
               
                   
                 User ID 
                 4815 
               
               
                   
                 Device ID 
                 7362 
               
               
                   
                 T1 timestamp data 
                 12-Jul-2008; 09:35:18.7 
               
               
                   
                 T2 timestamp data 
                 12-Jul-2008; 09:35:19.8 
               
               
                   
                 duration (Δt) 
                 00:00:01.1 
               
               
                   
                 T1 geo-location 
                 2650.9273, N, 08003.5193, W 
               
               
                   
                 data 
               
               
                   
                 1st interval 
                 2650.9281, N, 08003.5190, W 
               
               
                   
                 location data 
               
               
                   
                 2 nd  interval 
                 2650.9288, N, 08003.5188, W 
               
               
                   
                 location data 
               
               
                   
                 . 
                 . 
               
               
                   
                 . 
                 . 
               
               
                   
                 . 
                 . 
               
               
                   
                 Nth interval 
                 2650.9321, N, 08003.5177, W 
               
               
                   
                 location data 
               
               
                   
                 T2 geo-location 
                 2650.9325, N, 08003.5176, W 
               
               
                   
                 data 
               
               
                   
                 Product data 
                 Color = Red, Brand = ABC, 
               
               
                   
                   
                 Type/Batch = 224B-1 
               
               
                   
                 Locate request 
                 Requestor: XYZ Construction Company, 
               
               
                   
                 data 
                 Requested service address: 
               
               
                   
                   
                 222 Main St, Orlando, FL 
               
               
                   
               
            
           
         
       
     
     With regard to the marking material color information that may be included in marking device data  1252  as exemplified in Tables 1 and 2, Table 3 shows an example of the correlation of marking material color to the type of facility to be marked. 
     In another example, locate receiver data  1254  of locating equipment data  1250  may be electronic information (e.g., one or more electronic records) of data that is provided by electronic locate receiver devices and/or systems. Examples of a locate receiver device that may provide locate receiver data  1254  are described in U.S. Non-provisional patent application Ser. No. 12/704,087, entitled “Locate Apparatus Having Enhanced Features for Underground Facility Locate Operations, and Associated Methods and Systems,” filed on Feb. 11, 2010, which application is incorporated herein by reference in its entirety. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Correlation of color to facility type 
               
            
           
           
               
               
               
            
               
                   
                 Marking 
                   
               
               
                   
                 material 
               
               
                   
                 color 
                 Facility Type 
               
               
                   
                   
               
               
                   
                 White 
                 Proposed excavation 
               
               
                   
                 Pink 
                 Temporary survey markings 
               
               
                   
                 Red 
                 Electric power lines, cables or conduits, and 
               
               
                   
                   
                 lighting cables 
               
               
                   
                 Yellow 
                 Gas, oil, steam, petroleum, or other hazardous 
               
               
                   
                   
                 liquid or gaseous materials 
               
               
                   
                 Orange 
                 Communications, cable TV, alarm or signal lines, 
               
               
                   
                   
                 cables, or conduits 
               
               
                   
                 Blue 
                 Water, irrigation, and slurry lines 
               
               
                   
                 Purple 
                 Reclaimed water, irrigation and slurry lines 
               
               
                   
                 Green 
                 Sewers, storm sewer facilities, or other drain lines 
               
               
                   
                 Black 
                 Mark-out for errant lines 
               
               
                   
                   
               
            
           
         
       
     
     Table 4 below shows an example of a sample of locate receiver data  1254  of locating equipment data  1250  that may be captured, for example, at one or more times during operation/use of an appropriately configured locate receiver. Different models of locate receivers and transmitters are available from a variety of manufacturers and have different features; accordingly, it should be appreciated that the information content and type provided in Table 4 is exemplary of possible information relating to locate receivers on which a quality assessment of a locate operation may be based, and that other types and values for information are possible. With respect to information potentially provided by a given locate receiver as shown in Table 4 below, the “gain” is typically a measure of the degree of sensitivity of a locate receiver antenna that is picking up a signal emanating from along an underground facility (alternatively, “gain” may be viewed as a degree of amplification being applied to a received signal). Gain may be expressed in terms of any scale (e.g., 0-100), as a numeric value or percentage. “Signal strength” refers to the strength of a received signal at a given gain value; signal strength similarly may be expressed in terms of any scale, as a numeric value or percentage. Generally speaking, higher signal strengths at lower gains typically indicate more reliable information from a locate receiver, but this may not necessarily be the case for all locate operations. 
     In some exemplary implementations, an electronic record of a locate operation as obtained from a locate receiver may include multiple data entries as shown in the example of Table 4. Each such entry may not only include information about various operating parameters of the locate receiver (e.g., signal strength, gain), but may additionally include location information (geo-location data) associated with detected facilities, as well as various environmental data. The logging of a given entry by a locate receiver may automatically result from one or more conditions (e.g., signal strength exceeding a particular threshold) and/or respective data entries may be manually logged by a technician using the locate receiver (e.g., via a push button, touch screen, trigger actuation, or other interaction facilitated by a user interface of the locate receiver). In this manner, multiple pieces of data may be collected for an electronic record of a locate operation, including multiple pieces of geo-location data for a given underground facility detected via the locate receiver. 
     
       
         
           
               
             
               
                 TABLE 4 
               
               
                   
               
               
                 Example locate receiver data 1254 of locating equipment data 1250 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Service provider ID 
                 0482 
               
               
                   
                 Locate technician ID 
                 4815 
               
               
                   
                 Locate Device ID 
                 7345 
               
               
                   
                 Timestamp data 
                 12-Jul-2008; 09:35:15.2 
               
               
                   
                 Geo-location data 
                 N35°43.57518, W078°49.78314 
               
               
                   
                   
                 (deg. And dec. min.) 
               
               
                   
                 Locate mode 
                 Mode = PASSIVE; PEAK 
               
               
                   
                 Facility type 
                 Gas (yellow) 
               
               
                   
                 Ground type 
                 Pavement 
               
               
                   
                 Signal frequency 
                 60 Hz 
               
               
                   
                 Facility depth 
                 3.4 feet 
               
               
                   
                 Temperature data 
                 73 degrees F. 
               
               
                   
                 Humidity data 
                 30% 
               
               
                   
                 Light data 
                 4.3 volts 
               
               
                   
                 Compass data 
                 213 degrees 
               
               
                   
                 Inclinometer data 
                 −40 
               
               
                   
                 Accelerometer data 
                 0.275 g 
               
               
                   
                 Battery strength data 
                 85% 
               
               
                   
                   
               
            
           
         
       
     
     It should be appreciated that Table 4 represents only one non-limiting example of an electronic record of locate information which may be generated in accordance with the operation of a locate receiver, according to one embodiment. In particular, a single electronic record of locate information collected in connection with operation of a locate receiver may include multiple entries of a given data type. For example, while Table 4 illustrates an electronic record including a single GPS data point in connection with the detection of a gas facility, it should be appreciated that multiple GPS data points may be taken and stored within a single electronic record, for a single type of facility or for multiple different types of facilities detected during a locate operation. The multiple GPS data points may be taken in response to a single actuation event (e.g., single actuator pull by a technician), in response to multiple actuation events (e.g., multiple actuator pulls by a technician), or in other manners. Thus, multiple pieces of data may be collected for an electronic record of a locate operation, and it should be appreciated that any single electronic record may include multiple entries. 
     In another example, both marking device data  1252  and locate receiver data  1254  of locating equipment data  1250  may be electronic information (e.g., one or more electronic records) of data that is provided by a combined locate and marking device. An example of such a combined locate and marking device is described in U.S. Non-provisional application Ser. No. 12/569,192, filed on Sep. 29, 2009, entitled “Methods, Apparatus, and Systems for Generating Electronic Records of Locate and Marking Operations, and Combined Locate and Marking Apparatus for Same,” and U.S. Provisional Patent Application Ser. No. 61/102,122, filed on Oct. 2, 2008, entitled “Combination Locate and Marking Device With a Data Acquisition System Installed Therein, and Associated Methods,” which applications are both hereby incorporated herein by reference in their entirety. In some exemplary implementations, such devices may provide respective data sets of geographic information for the marking functionality and the locate functionality, while in other implementations such devices may provide only a single data set of geographic information representing both detection and marking of a given facility (e.g., presuming that, via use of a combined locate and marking device, marks are dispensed directly in response to detection of a facility at a given geographic location). 
     Table 5 below illustrates one non-limiting example of four actuation data sets that may be collected in an electronic record generated by a combined locate and marking device, in which each data set corresponds, for example, to a separate actuation event to dispense marking material. It should be appreciated, however, that these are merely examples, and that various alternative electronic records may be generated according to the aspects of the invention, for example reflecting different types of information associated with operation of a combination locate and marking device. 
     Each of the four records of Table 5 includes general information not limited to either the locate receiver functionality or marking functionality of the combination device, such as an identification of the service provider (Service provided ID), an identification of the user (User ID), an identification of the device (Device ID), and information about the requestor of the locate operation and the requested address (Locate request data). In addition, an entry describing the mode of data collection (e.g., Manual) for the device is also collected, which may indicate that information is logged into the record(s) upon actuation of the combined locate and marking device. Information about the actuation itself, such as the time of actuation (Timestamp data), actuation duration, and geographical location (geo-location data) at the start, during, and/or at and end of the actuation may also be included. The data sets also include information relating to the locate receiver functionality of the combination locate and marking device, including the receiver detection mode (i.e., PEAK in Table 5), the strength of a detected signal, and the frequency of the detected signal. Information relating to a depth measurement (Facility depth) is also included, as is information about the marking material to be dispensed by the combination locate and marking device. Again, it should be appreciated that Table 5 is an illustration of one electronic record including multiple data sets that may be generated in association with operation of a combination locate and marking device, and that other forms of electronic records are also possible. 
     
       
         
           
               
             
               
                 TABLE 5 
               
               
                   
               
               
                 Electronic Record for Combination Locate and Marking Device 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Record 
                 Service 
                 0482 
               
               
                 # 1001 
                 provider ID 
               
               
                   
                 User ID 
                 4815 
               
               
                   
                 Device ID 
                 7362 
               
               
                   
                 Device mode 
                 Mode = MANUAL 
               
               
                   
                 Timestamp data 
                 12-Jul-2008; 09:35:15 
               
               
                   
                 Actuation 
                 0.5 sec 
               
               
                   
                 duration 
               
               
                   
                 Start actuation 
                 2650.9348, N, 08003.5057, W 
               
               
                   
                 location data 
               
               
                   
                 End actuation 
                 2650.9353, N, 08003.5055, W 
               
               
                   
                 location data 
               
               
                   
                 Locate mode 
                 Mode = PEAK 
               
               
                   
                 Signal strength 
                 85% 
               
               
                   
                 (% of maximum) 
               
               
                   
                 Signal frequency 
                 1 kHz 
               
               
                   
                 Facility depth 
                 3.4 meters 
               
               
                   
                 Marking material 
                 Color = RED, Brand = ABC 
               
               
                   
                 data 
               
               
                   
                 Locate request 
                 Requestor = XYZ Construction Company, 
               
               
                   
                 data 
                 Requested service address = 
               
               
                   
                   
                 222 Main St, Orlando, FL 
               
               
                 Record 
                 Service 
                 0482 
               
               
                 # 1002 
                 provider ID 
               
               
                   
                 User ID 
                 4815 
               
               
                   
                 Device ID 
                 7362 
               
               
                   
                 Device mode 
                 Mode = MANUAL 
               
               
                   
                 Timestamp data 
                 12-Jul-2008; 09:35:18 
               
               
                   
                 Actuation 
                 0.4 sec 
               
               
                   
                 duration 
               
               
                   
                 Start actuation 
                 2650.9256, N, 08003.5234, W 
               
               
                   
                 location data 
               
               
                   
                 End actuation 
                 2650.9256, N, 08003.5226, W 
               
               
                   
                 location data 
               
               
                   
                 Locate mode 
                 Mode = PEAK 
               
               
                   
                 Signal strength 
                 85% 
               
               
                   
                 (% of maximum) 
               
               
                   
                 Signal frequency 
                 1 kHz 
               
               
                   
                 Facility depth 
                 3.4 meters 
               
               
                   
                 Marking material 
                 Color = RED, Brand = ABC 
               
               
                   
                 data 
               
               
                   
                 Locate request 
                 Requestor = XYZ Construction Company, 
               
               
                   
                 data 
                 Requested service address = 
               
               
                   
                   
                 222 Main St, Orlando, FL 
               
               
                 Record 
                 Service 
                 0482 
               
               
                 # 1003 
                 provider ID 
               
               
                   
                 User ID 
                 4815 
               
               
                   
                 Device ID 
                 7362 
               
               
                   
                 Device mode 
                 Mode = MANUAL 
               
               
                   
                 Timestamp data 
                 12-Jul-2008; 09:35:21 
               
               
                   
                 Trigger pull 
                 0.5 sec 
               
               
                   
                 duration 
               
               
                   
                 Start actuation 
                 2650.9273, N, 08003.5193, W 
               
               
                   
                 location data 
               
               
                   
                 End actuation 
                 2650.9281, N, 08003.5190, W 
               
               
                   
                 location data 
               
               
                   
                 Locate mode 
                 Mode = PEAK 
               
               
                   
                 Signal strength 
                 85% 
               
               
                   
                 (% of maximum) 
               
               
                   
                 Signal frequency 
                 1 kHz 
               
               
                   
                 Facility depth 
                 3.4 meters 
               
               
                   
                 Marking material 
                 Color = RED, Brand = ABC 
               
               
                   
                 data 
               
               
                   
                 Locate request 
                 Requestor = XYZ Construction Company, 
               
               
                   
                 data 
                 Requested service address = 
               
               
                   
                   
                 222 Main St, Orlando, FL 
               
               
                 Record 
                 Service 
                 0482 
               
               
                 # 1004 
                 provider ID 
               
               
                   
                 User ID 
                 4815 
               
               
                   
                 Device ID 
                 7362 
               
               
                   
                 Device mode 
                 Mode = MANUAL 
               
               
                   
                 Timestamp data 
                 12-Jul-2008; 09:35:25 
               
               
                   
                 Actuation 
                 0.5 sec 
               
               
                   
                 (actuation) 
               
               
                   
                 duration 
               
               
                   
                 Start actuation 
                 2650.9321, N, 08003.5177, W 
               
               
                   
                 location data 
               
               
                   
                 End actuation 
                 2650.9325, N, 08003.5176, W 
               
               
                   
                 location data 
               
               
                   
                 Locate mode 
                 Mode = PEAK 
               
               
                   
                 Signal strength 
                 85% 
               
               
                   
                 (% of maximum) 
               
               
                   
                 Signal frequency 
                 1 kHz 
               
               
                   
                 Facility depth 
                 3.4 meters 
               
               
                   
                 Marking material 
                 Color = RED, Brand = ABC 
               
               
                   
                 data 
               
               
                   
                 Locate request 
                 Requestor = XYZ Construction Company, 
               
               
                   
                 data 
                 Requested service address = 
               
               
                   
                   
                 222 Main St, Orlando, FL 
               
               
                   
               
            
           
         
       
     
     While the collection and logging of locate information and marking information to generate an electronic record is discussed in some aspects, for purposes of illustration, in terms of actuation data sets (i.e., a set of data that is associated and logged with a corresponding actuation of a locate device, marking device, or combined locate and marking device), it should be appreciated that electronic records as discussed herein are not limited in this respect. More generally, an electronic record of a locate and/or marking operation may be generated in any of a variety of manners, have a variety of file formats and/or data structures, and include any of a variety of locate information and/or marking information (some of which may be germane to one or more actuations of a device, some of which may be common to multiple actuations or the overall locate and/or marking operation in general, and some of which may not be related to specific actuations). For example, in some exemplary implementations electronic records may be a “flat files” including a succession of time stamped “event entries” of various locate information and/or marking information (logged automatically as a result of one or more particular conditions, e.g., exceeded thresholds for various signals, or manually as a result of user actuation of a device), or a differently formatted file (e.g., an ASCII file, an XML file) having a data structure that segregates or separates in some manner the locate information and/or marking information into multiple different fields. 
     It should also be appreciated that one or both of the marking device data  1252  and locate receiver data  1254  of locating equipment data  1250 , received from any of the marking devices, locate devices, or combined locate and marking devices referenced above, may include landmark information (in addition to, or alternatively to, locate information and marking information). Landmark information may include any information relating to one or more environmental landmarks of interest (e.g., in and around the work site/dig area and/or generally in the vicinity of the locate and marking operation). Examples of landmark information include, but are not limited to, geo-location data of an environmental landmark, type of environmental landmark, and a time stamp for any acquired information relating to an environmental landmark. In some instances, landmark information may be acquired from locate equipment particularly configured to operate in a landmark mode so as to acquire such information, as well as one or more other modes (e.g., “locate mode” or “marking mode”) to accomplish functions relating to detection and/or marking of underground facilities. 
     Tables 6A and 6B below show examples of landmark information that may be included in an electronic record forming part of either marking device data  1252  or locate receiver data  1254  of locating equipment data  1250 . Table 6A shows the format and content of an electronic record entry for a utility pole, which includes one geo-location data point, and Table 6B shows the format and content of an electronic record entry for a pedestal, which includes four geo-location data points (i.e., one for each corner of the pedestal). As noted above, it should be appreciated that the format and content shown below in Tables 6A and 6B is provided primarily for purposes of illustration, and that a variety of formats and content may be employed for an electronic record entry for landmark information. 
     
       
         
           
               
             
               
                 TABLE 6A 
               
               
                   
               
               
                 Example record of landmark information acquired for a utility pole 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Record 
                 Service 
                 0482 
               
               
                 # 1 
                 provider ID 
               
               
                   
                 User ID 
                 4815 
               
               
                   
                 Device ID 
                 7362 
               
               
                   
                 Type of EL 
                 Type = utility pole 
               
               
                   
                 timestamp data 
                 12-Jul-2008; 09:35:17.5 
               
               
                   
                 geo-location data 
                 2650.9256, N, 08003.5234, W 
               
               
                   
                 Locate request 
                 Requestor: XYZ Construction Company, 
               
               
                   
                 data 
                 Requested service address: 
               
               
                   
                   
                 222 Main St, Orlando, FL 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 6B 
               
               
                   
               
               
                 Example record of landmark information acquired for a pedestal 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 Record 
                 Service 
                 0482 
               
               
                 # 2 
                 provider ID 
               
               
                   
                 User ID 
                 4815 
               
               
                   
                 Device ID 
                 7362 
               
               
                   
                 Type of EL 
                 Type = pedestal 
               
               
                   
                 Timestamp data 
                 12-Jul-2008; 09:35:17.5 
               
               
                   
                 geo-location data 
                 2650.9256, N, 08003.5234, W 
               
               
                   
                 Type of EL 
                 Type = pedestal 
               
               
                   
                 Timestamp data 
                 12-Jul-2008; 09:35:21.2 
               
               
                   
                 geo-location data 
                 2650.9256, N, 08003.5226, W 
               
               
                   
                 Type of EL 
                 Type = pedestal 
               
               
                   
                 Timestamp data 
                 12-Jul-2008; 09:35:26.7 
               
               
                   
                 geo-location data 
                 2650.9288, N, 08003.5188, W 
               
               
                   
                 Type of EL 
                 Type = pedestal 
               
               
                   
                 Timestamp data 
                 12-Jul-2008; 09:35:33.5 
               
               
                   
                 geo-location data 
                 2650.9321, N, 08003.5177, W 
               
               
                   
                 Locate request 
                 Requestor: XYZ Construction Company, 
               
               
                   
                 data 
                 Requested service address: 
               
               
                   
                   
                 222 Main St, Orlando, FL 
               
               
                   
               
            
           
         
       
     
     D. Electronic Manifests 
     Electronic Manifest (EM) application  1260  of data sources  1216  is a computer software application that may be used to create an electronic manifest of a locate and/or marking operation. As discussed above, an electronic manifest may include a digital (e.g., aerial) image of the work site/dig area and its surroundings, upon which may be overlaid any of a variety of information relating to a locate and/or marking operation (e.g., derived from any of the information discussed above in connection with electronic records generated by various locate equipment). In one example of an electronic manifest, one or more “electronic locate marks” are overlaid on a digital image for indicating corresponding physical locate marks that have been placed on the ground, pavement or other surface at the site, thereby indicating the geo-locations and types of facilities present. One or more detection marks corresponding to detected facilities, as well as one or more landmarks, also may be indicated on the digital image together with the electronic locate marks. Via the EM application  1260 , the digital images may be marked up “manually” by a technician (e.g., using a stylus or other type of user interface in conjunction with the digital image displayed in a display field) to include one or more electronic locate marks, detection marks and/or one or more identifiers for environmental landmarks. Alternatively, a digital image may be marked up “automatically” by importing data, for example, from one or more pieces of locate equipment (e.g., a locate device, a marking device, or a combined locate and marking device) and overlaying the imported data on the digital image. 
     In one example, the starting digital images to be marked up using EM application  1260  may be VWL images  1232  that are associated with tickets  1220 . In this manner, the resulting EM image may contain the original dig area indicator (e.g., from the VWL image) to indicate or delimit the dig area for the locate and marking operation, together with any electronic locate marks and/or landmarks added to the image via the EM application. The marked up digital images may be saved as, for example, EM images  1262 , which may be associated with, for example, tickets  1220  and may be used by locate companies to support proof of work compliance. In some embodiments, EM application  1260  may be implemented as described in U.S. patent application Ser. No. 12/831,330, filed Jul. 7, 2010, and entitled “METHODS, APPARATUS AND SYSTEMS FOR GENERATING SEARCHABLE ELECTRONIC RECORDS OF UNDERGROUND FACILITY LOCATE AND/OR MARKING OPERATIONS,” which application is incorporated by reference herein in its entirety. 
     As noted above in connection with VWL images  1232  provided by VWL application  1230 , an EM image  1262  may include metadata corresponding to any markings or content in the image; in particular, geographic coordinates (e.g., latitude and longitude values) for any dig area indicator, electronic locate marks, detection marks, and/or landmarks marked on the image may accompany or be included in an image file as metadata. Accordingly, these geographic coordinates, as well as any other information provided by EM application, may be employed in some manner as part of a quality assessment process (e.g., as field information/data, or in some instances as reference information/data, or in some instances to pre-process or filter one or both of field information/data and reference information/data prior to comparison). 
       FIG. 5  shows an example of an electronic manifest  900  that comprises both image data and non-image data. In this example, the electronic manifest  900  comprises a marked-up image  905  showing locate mark indicators  910  (e.g., to indicate locations of physical locate marks), offset indicia  915  (e.g., to indicate distances between physical locate marks and certain environmental landmarks) and dig area indicators  920  (e.g., as provided by an excavator on a VWL image). In addition, the electronic manifest  900  comprises non-image information relating to the locate and/or marking operation, such as a ticket number or identifier  925 , a name or identifier  930  associated with the locate technician (which may indicate facility owner/operator, or locate company/technician), a time and date stamp  935  indicating when the electronic manifest was created, a location stamp  940  indicating where the electronic manifest was created, a completed checklist  945  of markings used in the locate and/or marking operation, and a locate technician signature  950  certifying that the information of the electronic manifest is correct. 
     Although  FIG. 5  shows an example of an electronic manifest including specific types of ticket information, it should be appreciated that an electronic manifest as described herein is not limited in this regard, and may alternatively include other combinations of ticket information. Also, an electronic manifest may be displayed and/or formatted in manners different from the example shown in  FIG. 5 . 
     The underlying electronic data used to generate an electronic manifest (e.g., the electronic manifest  900  shown in  FIG. 5 ) may be represented and/or stored in any suitable manner, as the present disclosure is not limited in this respect. In some embodiments, the marked-up image(s) and the non-image information may be stored as a single file. For example, the non-image information may be included as metadata associated with the marked-up image(s). In other embodiments, the marked-up image(s) and the non-image information may be formatted as separate data sets and may be transmitted and/or stored separately. In another aspect, whether transmitted/stored separately or together, the marked-up image(s) and the non-image information may be linked together in some manner as relating to a common electronic record. 
       FIG. 6  shows an example of a data set  1000  that may be used to generate an electronic manifest. In this example, the data set  1000  may include a timestamp field  1010 , a facility type identifier field  1020 , a facility mark location field  1030 , an environmental landmark identifier field  1040 , an environmental landmark location field  1050 , an other information field  1060 , a facility owner/operator field  1065 , a marking method field  1070 , a property address field  1080 , a ticket number field  1090 , a location stamp field  1015 , and a certification field  1025 . 
     Although  FIG. 6  shows specific examples of information fields, it should be appreciated that the present disclosure is not limited in this regard. In other implementations, the data set  1000  may include additional, fewer, or different fields. Some exemplary information fields are discussed briefly below. 
     The timestamp field  1010  may include time data that identifies the day and/or time that a locate and/or marking operation is performed. This may coincide with a time at which an environmental landmark location is identified in connection with the dig area. The time data in the timestamp field  1010  is shown in  FIG. 6  as 9:43 a.m. on Oct. 20, 2005, although any type of date and/or time code may be used. The information in timestamp field  1010  may be useful in establishing when a locate and/or marking operation occurred. 
     The facility type identifier field  1020  may include an identifier that identifies a type of underground facility that is being marked. The identifier in the facility type identifier field  1020  is shown in  FIG. 6  as “power,” although any type of identifier may be used. The facility mark location field  1030  may include geographical information corresponding to a physical locate mark. In some implementations, the geographical information may identify a set of geographical points along a marking path of a located facility line. The geographical information in the facility mark location field  1030  is shown in  FIG. 10  as N38°51.40748, W077°20.27798; . . . ; N38°51.40784, W077°20.27865, although any type of geographical information may be used. 
     The information in the facility mark location field  1030  may be useful in graphically presenting the facility locate marks on a map, and/or to verify that the locate and/or marking operation was actually and accurately performed. Additionally, or alternatively, the facility mark location field  1030  may include geographical information for multiple facility locate marks. 
     The environmental landmark identifier field  1040  may include an identifier that identifies a type of environmental landmark being marked. The identifier in environmental landmark identifier field  1040  is shown in  FIG. 6  as “curb,” although any type of identifier may be used. The environmental landmark location field  1050  may include geographical information corresponding to the environmental landmark identified in the environmental landmark identifier field  1040 . The geographical information in the environmental landmark location field  1050  is shown in  FIG. 6  as N38°51.40756, W077°20.27805; . . . ; N38°51.40773, W077°20.27858, although any type of geographical information may be used. 
     The other information field  1060  may store any other data that may be useful, including user notes, such as offset or distance information that identifies a distance between one or more environmental landmarks and one or more facility locate marks. The other information field  1060  is shown in  FIG. 6  as including “1.2 meters between curb and power line,” although any other data may be used. Additionally, or alternatively, the other information field  1060  may include audio/voice data, transcribed voice-recognition data, or the like to incorporate user notes. 
     E. Facilities Maps 
     Facilities maps  1280  of data sources  1216  are any physical, electronic, or other representation of the geographic location, type, number, and/or other attributes of a facility or facilities. Facilities maps  1280  may be supplied by the various facility owners and may indicate the geographic location of the facility lines (e.g., pipes, cables, and the like) owned and/or operated by the facility owner. For example, facilities maps  1280  may be supplied by the owner of the gas facilities, power facilities, telecommunications facilities, water and sewer facilities, and so on. In the process of performing the automatic quality assessment, information processing component  1210  may aggregate the information that is contained in multiple facilities maps  1280  in order to determine all the facilities that are present in and around a certain work site/dig area. 
     As indicated above, facilities maps may be provided in any of a variety of different formats. As facilities maps often are provided by facility owners of a given type of facility, typically a set of facilities maps includes a group of maps covering a particular geographic region and directed to showing a particular type of facility disposed/deployed throughout the geographic region. One facilities map of the set of maps is sometimes referred to in the relevant arts as a “plat.” 
     Perhaps the simplest form of facilities maps is a set of paper maps that cover a particular geographic region. In addition, some facilities maps may be provided in electronic form. An electronic facilities map may in some instances simply be an electronic conversion (i.e., a scan) of a paper facilities map that includes no other information (e.g., electronic information) describing the content of the map, other than what is printed on the paper maps. 
     Alternatively, however, more sophisticated facilities maps also are available which include a variety of electronic information, including geographic information and other detailed information, regarding the contents of various features included in the maps. In particular, facilities maps may be formatted as geographic information system (GIS) map files, in which map features (e.g., facility lines and other features) are represented as shapes and/or lines, and the file provides metadata describing the geographic locations and types of map features. In some examples, a GIS map file may indicate a facility line using a straight line, and may include some symbol or other annotation (e.g., a diamond shape) at each endpoint of the line to indicate where the line begins and terminates. From the foregoing, it should be appreciated that in some instances, given that the geo-locations of two termination or end-points of a given facility line may be provided by the map, the geo-location of any point on the facility line may be determined from these two end-points. 
     Examples of a wide variety of environmental landmarks that may be represented in a GIS facilities map file include, but are not limited to: landmarks relating to facilities such as pedestal boxes, utility poles, fire hydrants, manhole covers and the like; one or more architectural elements (e.g., buildings); and/or one or more traffic infrastructure elements (e.g., streets, intersections, curbs, ramps, bridges, tunnels, etc.). A GIS facilities map file may also include various shapes or symbols indicating different environmental landmarks relating to facilities, architectural elements, and/or traffic infrastructure elements. 
     Examples of information provided by metadata for the map file (i.e., included as part of the electronic file for the map) include, but are not limited to, information about the geo-location of various points along a given line, the termination points of a given line (e.g., the diamond shapes indicating the start and end of the line), the type of facility line (e.g., facility type and whether the line is a service line or main), geo-location of various shapes and/or symbols for other features represented in the map (environmental landmarks relating to facilities, architectural elements, and/or traffic infrastructure elements), and type information relating to shapes and/or symbols for such other features. 
     Facilities maps may include additional information that may be useful to a quality assessment process. For example, various information that may be included in a legend of the facilities map, or otherwise associated with the facilities map (e.g., included in the metadata or otherwise represented on the map), and available for use in a quality assessment process, may include, but is not limited to, a date of the facilities map (e.g., when the map was first generated/created, and/or additional dates corresponding to updates/revisions), a number of revisions to the facilities map (e.g., revision number, which may in some instances be associated with a date), one or more identifiers for a source, creator, owner and/or custodian of the facilities map (e.g., the owner of the facility type represented in the map), various text information (e.g., annotations to update one or more aspects or elements of the map), and any other legend information that may be included or represented in the map. 
       FIG. 7  shows an example of a visual representation of a portion of an electronic facilities map  500 . In this example, facilities map  500  is a telecommunications facilities map that is supplied by a telecommunications company. Facilities map  500  shows telecommunications facilities in relation to certain landmarks, such as streets and roads, using lines and shapes. As discussed above, the electronic facilities map may include metadata indicating what various lines, symbols and/or shapes represent, and indicating the geo-location of these lines, symbols and/or shapes. With respect to exemplary environmental landmarks, facilities map  500  may include both visual information and metadata relating to utility poles  502 , manhole  504 , and any of a variety of other landmarks that may fall within the geographic area covered by the facilities map  500 . 
     Additional details regarding the use of information derived from one or more facility maps as part of an automated quality assessment process for locate and/or marking operations is discussed in U.S. Non-provisional application Ser. No. 12/571,356, filed Sep. 30, 2009, entitled “METHODS AND APPARATUS FOR ANALYZING LOCATE AND MARKING OPERATIONS WITH RESPECT TO FACILITIES MAPS,” which application is hereby incorporated herein by reference. 
     IV. Exemplary Automated Assessment Methods 
       FIG. 8  shows a flow diagram of an exemplary process  1300  for performing a quality assessment of an underground facility locate and/or marking operation, as implemented by automated quality assessment application  1200 . While the example provided in  FIG. 8  is a more specific example of the generic process  1900  discussed above in connection with  FIG. 3 , and describes an automated quality assessment based on a completed or closed ticket for which it is presumed that a locate and/or marking operation was actually performed by a technician, it should be appreciated that the concepts generally outlined in the process  1300  may be applied to various types of available information relating to a requested locate operation and marking operation, whether performed separately or in tandem, and irrespective of actual performance of the locate operation and/or the marking operation, so as to assess the quality of the requested operation. 
     Process  1300  begins at act  1310 , where a completed (i.e., closed) ticket is received and associated information to be used in assessing the quality of a locate and/or marking operation, for example, performed in connection with the ticket is collected by automated quality assessment application  1200 . The associated ticket information may include, for example, the originating ticket information (e.g., textual ticket information  1222  of a certain ticket  1220 ), and one or more of the VWL images (e.g., a VWL image  1232  of a certain ticket  1220 ), the originating ticket assessment (e.g., a ticket assessment outcome  1242  of a certain ticket  1220 ), the locating equipment data (e.g., marking device data  1252  and/or locate receiver data  1254  of a certain ticket  1220 ), the EM images (e.g., a EM image  1262  of a certain ticket  1220 ), and any other information (e.g., from other electronic information and/or records  1295 ). 
     The process then continues to act  1312 , where the received information is used to automatically assess the quality of the locate and/or marking operation. In the example of  FIG. 8 , a locate and/or marking operation is categorized as either (a) APPROVED—the operation is approved, no further action needed; (b) SATISFACTORY—the operation is approved, but the locate technician needs coaching or training; (c) UNSATISFACTORY—the operation is not approved, the ticket needs QC action; or (d) PROMPT—an aspect of the operation assessment may be suitable for transmitting a real-time prompt to the locate technician with respect to, for example, performing a substantially immediate verification and/or corrective action. However, the invention is not limited in this respect, as any suitable indication of quality may be provided as a result of an automatic quality assessment, such as, a numerical score (e.g., a score from 0-100%), a letter grade, another type of graduated indictor based on some scale or range, or any other indication of quality. Additional details and examples of how quality may be automatically assessed at act  1312  and an indication (e.g., a categorization) of quality may be automatically generated at act  1314  are discussed below. It should be appreciated that the invention is not limited to these particular examples, and that such examples are provided primarily for the purposes of illustration. 
     In some implementations, the process  1300  of automated assessment may be carried out on a partially completed ticket (i.e., a ticket which has not been closed). As an example, the process  1300  may be executed in real-time, or near real-time, as locating equipment data  1250  (e.g., marking information, locate information, landmark information) is generated and received by a system executing the process  1300 . In one embodiment, as discussed further below, locate receiver data  1254  (“locate information”) and marking device data  1252  (“marking information”) received as locating equipment data may be compared to each other as part of an automated assessment process. Additionally or alternatively, in one aspect, the system may have access to certain data (e.g., historical data) that can serve as reference information, and one or both of marking information and locate information received as locating equipment data may be compared to the reference information. For example, in one embodiment of process  1300 , marking device data  1252  may be compared to historical marking data, historical locate receiver data  1254 , or historical landmark data in real-time or near real-time as a technician marks a facility. 
     V. Quality Assessments Based on Comparison of Marking Information and Locate Information 
     In some embodiments, a quality assessment of a locate and/or marking operation may be based on a comparison of different types of field information, in which one type of the field information itself serves as reference information for another type of the field information. For example, in one embodiment, first field information relating to a marking operation (“marking information”) may be compared with reference information in the form of second field information relating to a locate operation (“locate information”). It should be appreciated that in embodiments in which different types of field information are compared with each other, in some situations the distinction between “field information” and “reference information” may not have any practical effect; however, in other situations, it may be desirable to designate one type of the field information as the “reference information” for purposes of comparison (e.g., for various reasons, it may be presumed a priori that a first type of field information is generally more reliable than a second type of field information, and that hence the first type of field information is taken as the “reference information” for purposes of comparative analysis). 
     In one aspect of embodiments in which marking information and locate information are compared with each other, the marking information and the locate information may pertain to the same work site/dig area and represent corresponding locate and marking operations both performed in response to the same locate request ticket (such that the marking information and locate information essentially are obtained concurrently). In another aspect, the marking information and the locate information may pertain to the same work site/dig area, but one of the marking information and the locate information may have been acquired in connection with performance of a different locate request ticket (e.g., one of the marking information and the locate information may be obtained from a “historical ticket”). With respect to one of the marking information and the locate information being obtained from a historical ticket, it should be appreciated that the same technician may or may not have been responsible for obtaining the respective marking information and locate information forming the basis of the comparative analysis. Additional details regarding the use of historical information as part of an automated quality assessment process for locate and/or marking operations is discussed in U.S. Non-provisional patent application Ser. No. 12/572,202, filed Oct. 1, 2009, and entitled “Methods and Apparatus for Analyzing Locate and Marking Operation with Respect to Historical Information,” which application is incorporated herein by reference. 
     In various embodiments of the present invention, it should be appreciated that any constituent portion of marking information (e.g., as discussed above in Section III.C) may be compared to any constituent portion of locate information (e.g., as discussed above in Section III.C), based on any of a variety of criteria and metrics, to assess a quality of the locate and/or marking operation. In one example discussed in detail below, geographic information contained in marking information and locate information, respectively, provides a basis of comparison on which quality is assessed. However, in other exemplary implementations, alternatively to or in addition to geographic information, other information such as timing information, ticket information, service-related information, environmental information, operational information, etc., may be utilized in some manner, from one or both of the marking information and the locate information, to facilitate a quality assessment. 
     More specifically, in some exemplary embodiments “marking geo-location data” (e.g., one or more sets of latitude and longitude coordinates) relating to the marking of a given underground facility during a marking operation are compared to “locate geo-location data” relating to the detection of that facility during a locate operation. In this manner, a correspondence or discrepancy (or degree of correspondence) may be ascertained between the marking geo-location data and the locate geo-location data. As discussed in greater detail below, a first set of marking latitude and longitude coordinates constituting lines or curves representing underground facilities marked during a marking operation may be compared to a second set of locate latitude and longitude coordinates constituting lines or curves representing underground facilities detected during a locate operation to determine a degree of matching between the two sets, in a manner akin to pattern matching. This may be useful in determining how closely the physical locate marks formed by the technician during a marking operation correspond to the presumed physical location(s) of the underground facilities as detected during a locate operation. 
       FIG. 9  is a flow chart of an exemplary process  600  for performing the act  1312  of the process  1300  shown in  FIG. 8 , according to one embodiment, and illustrates one technique that may be used to perform an assessment based on a comparison of marking information and locate information. In the exemplary method outlined in  FIG. 9 , the reference data is constituted by locate geo-location data. In one aspect, the locate geo-location data may be from a corresponding locate operation conducted at essentially the same time at the same work site/dig area by the same technician. Alternatively, in another aspect the locate geo-location data may be historical locate receiver data relating to the same work site/dig area. Although the method of  FIG. 9  presumes that locate information serves as the reference information, it should be appreciated that in other exemplary methods, marking information may serve as the reference information to which locate information is compared; i.e., locate geo-location data generated pursuant to a locate operation (e.g., locate receiver data) may be compared to reference data constituted by marking geo-location data (e.g., from a corresponding marking operation or historical marking data). It should also be appreciated that the geographic information on which comparisons are based may be obtained, for example, from one or more of locating equipment data (e.g., various types of electronic records given in Tables 1-6 above), an EM application or EM image, historical tickets, and/or other sources of geographic information relating to the locate and/or marking operation. 
     At act  601  of the process  600 , a particular facility type that has been marked during a marking operation may be selected for comparison to locate information corresponding to a same facility type at the same work site/dig area. For example, if it is determined (e.g., from available electronic records of a marking operation) that a locate technician has marked electric lines, gas lines, and sewer lines during the marking operation, one of these facility types may be selected initially for comparison to corresponding locate information. It should be understood that the process  600  may be repeated to perform one or more additional comparisons for one or more of the other facility types; for example, if electric lines are the facility type that is selected at act  601 , process  600  may be performed again (e.g., subsequently or in parallel) to select one of the other facility types that has been marked. 
     In one aspect of this embodiment, as part of act  601 , all of the different facility types marked and represented in the available electronic record of the marking operation are first determined from data in the electronic record indicating the color(s) of marking material used during the marking operation. As explained above in connection with Table 3, each marking material color corresponds to a particular facility type. Thus, if actuation data in an electronic record of a marking operation indicates that red, yellow, and green marking material were each used during the marking operation, then it may be determined that electric lines, gas lines, and sewer lines were marked. 
     Once it is determined what types of a facilities were marked during the marking operation, a particular type of facility marked may be selected as the subject for assessment by comparison to corresponding locate information in any of a variety of ways. For example, in some embodiments, a type of facility for which such a comparison has not yet been performed may be selected. In situations where there are multiple facility types for which the comparison has not yet been performed, the facility type may be selected via user input pursuant to a selection query, may be selected based on a risk assessment associated with each facility type, or alternatively may be selected randomly or based on some other factor (e.g., the time at which the facility was marked relative to the other facilities, the number or length of locate marks used to mark the facility). 
     Once a particular facility type is selected at act  601 , the process continues to act  603 , where particular marking information regarding the locate marks for the selected facility type is extracted as necessary from the available electronic record to provide the marking geo-location data for comparison to corresponding locate information. For example, if the selected facility type is electric lines, then the actuation data sets of an electronic record generated by the marking device (e.g., of the type shown in Table 2 above) indicating that red marking material was dispensed during the locate and/or marking operation may be used to provide the marking geo-location data. 
     More specifically, as a result of act  603 , a set of marking geo-location data points (e.g., coordinate pairs of GPS latitude and longitude values) are identified that are indicative of geographical locations at which marking material of the color of the selected facility type was dispensed. For example, as shown in Table 2, an actuation data set for a marking device actuation includes a set of geo-location data points at which the marking device was actuated (and dispensed marking material). In the example of Table 2, the geo-location data set for act-1 includes the data points 2650.9348N,08003.5057W, 2650.9353N,08003.5055W, and 2650.9356N,08003.5055W. At act  603 , any one or more of these points (along with the other geo-location data points at which the marking device was actuated using the same color) may be selected to be included in the marking geo-location data. In one example, all geo-location data points from the marking device actuation data sets for the selected facility type (i.e., all geo-location data from all actuation data sets indicating the marker color corresponding to the selected facility type) are selected to be in the set of marking geo-location data points that is compared to locate geo-location data. However, the invention is not limited in this respect, as in some embodiments, only a subset of the marking geo-location data points may be selected for comparison. 
     For example, in some embodiments, geo-location data points at which marking material was dispensed as part of a dotting pattern may be disregarded and not included in the marking geo-location data, while geo-location data points dispensed as part of a lines pattern may be included in the marking geo-location data. As known in the relevant art, there are multiple types of marking patterns that may be used in a marking operation. For example, a “dotting” pattern may be utilized to quickly mark the location of the target facility. Often the dotting pattern is used in conjunction with the initial locate operation to detect the target facility. A “lines” pattern is typically the end product of the marking operation. This pattern extends the dotting pattern in order to create locate marks in the form of dashed lines that indicate the presence or absence of an underground facility. 
     Because the locate marks for the dotting pattern are initial marks that may be “revised” by the marks from the lines pattern, in some embodiments it may be desirable to exclude the geo-location points of marks from the dotting pattern from the marking geo-location data used for comparison to locate geo-location data. To this end, geo-location points of marks from a dotting pattern may be identified and distinguished from geo-location points of marks from a lines pattern in a variety of ways. An example of one such way is described below, though a variety other techniques could be used. 
     In some embodiments, geo-location points from a marking device actuation data set corresponding to a dotting pattern may be distinguished from geo-location points corresponding to a lines pattern based on information in the actuation data set for the marking device actuation that identifies the duration of the actuation (see Table 2). If the duration of the marking device actuation is less than a threshold amount of time, the actuation may be considered to correspond to a dotting pattern, and the geo-location points from this actuation data set may be excluded from the marking geo-location data used for comparison to locate geo-location data. If, on the other hand, the duration is equal to or greater than the threshold, the actuation may be considered to correspond to a lines pattern, and the geo-location points from this actuation data set may be included in the set of marking geo-location data points to be compared to the locate geo-location data. 
     After act  603 , process  600  continues to act  605 , where one or more electronic records of locate operations in the same work site/dig area and corresponding to the selected type of facility are accessed, and locate geo-location data is extracted from the one or more electronic records for comparison with the marking geo-location data. Accordingly, as a result of act  605 , a set of “locate geo-location data points” indicating the detected physical location of a facility line of the type of the selected facility is obtained for comparison to the set of marking geo-location data points obtained in act  603 . 
     One or more appropriate electronic records of locate operations (either “current” or “historical”) from which locate geo-location data is extracted may be selected in a variety of ways, as the invention is not limited in this respect. For example, with reference again to the discussion above in connection with Tables 1-6, exemplary electronic records of locate operations generally include information that may be searched based on a variety of criteria for some type of correspondence to the marking geo-location data (e.g., electronic records of locate operations generally include type(s) of facilities detected to which geo-location data in the record(s) corresponds, various service information such as user ID, device ID, and/or ticket information such as an address, description, and/or other indicia of the work site/dig area, including geographic coordinates for the dig area, etc., any of which may be searched to determine appropriate correspondence to the marking geo-location data). 
     In some implementations, electronic records of locate operations and corresponding marking operations performed pursuant to the same locate request ticket may include one or more identifiers that link the respective records of locate and marking operations (e.g., related file identifiers, user IDs, device IDs, etc.) to facilitate ready identification of marking geo-location data and locate geo-location data for comparison. For situations in which a combined locate and marking device is employed for performance of a locate and marking operation, locate geo-location data and marking geo-location data already may be organized, coded and/or tagged as related records, or form part of the same electronic record. 
     In other exemplary implementations, geo-location coordinates of a point that constitutes the centroid of the set of marking geo-location data points obtained in act  603  may be determined, and an appropriate set of locate geo-location data points may be selected that corresponds to the selected facility type and includes the geo-location coordinates corresponding to this centroid. In yet other implementations in which a VWL image provided by an excavator is available (e.g., as part of a locate request ticket), the geo-locations for the boundary of the dig area in which work is planned (e.g., latitude and longitude coordinates for the dig area indicator in the VWL image that denotes/delimits the dig area) may be determined from the VWL image and/or included in the locate request ticket. Accordingly, an appropriate set of locate geo-location data points may be selected that corresponds to the selected facility type and is within the area delimited by the geo-locations for the dig area boundary. 
     After act  605 , the process next continues to act  607 , in which it is determined if any conversion is required of either or both of the set of marking geo-location data points obtained at act  603  and the set of locate geo-location data points obtained at act  605  and, if so, conversion to a common reference frame (e.g., a common coordinate system) is performed. 
     As known in the relevant art, a geographic or “global” coordinate system (i.e., a coordinate system in which geographic locations on Earth are identified by a latitude and a longitude value, e.g., (LAT,LON)) may be used to identify geographic locations of locate marks and detected facilities. In a “geocentric” global coordinate system (i.e., a coordinate system in which the Earth is modeled as a sphere), latitude is defined as the angle from a point on the surface of a sphere to the equatorial plane of the sphere, whereas longitude is defined as the angle east or west of a reference meridian between two geographical poles of the sphere to another meridian that passes through an arbitrary point on the surface of the sphere. Thus, in a geocentric coordinate system, the center of the Earth serves as a reference point that is the origin of the coordinate system. However, in actuality the Earth is not perfectly spherical, as it is compressed towards the center at the poles. Consequently, using a geocentric coordinate system can result in inaccuracies. 
     In view of the foregoing, the Earth is typically modeled as an ellipsoid for purposes of establishing a global coordinate system. The shape of the ellipsoid that is used to model the Earth and the way that the ellipsoid is fitted to the geoid of the Earth is called a “geodetic datum.” In a “geodetic” global coordinate system, the latitude of a point on the surface of the ellipsoid is defined as the angle from the equatorial plane to a line normal to the reference ellipsoid passing through the point, whereas the longitude of a point is defined as the angle between a reference plane perpendicular to the equatorial plane and a plane perpendicular to the equatorial plane that passes through the point. Thus, geodetic latitude and longitude of a particular point depends on the geodetic datum used. 
     A number of different geodetic global coordinate systems exist that use different geodetic datums, examples of which include WGS84, NAD83, NAD27, OSGB36, and ED50. As such, a geographic point on the surface of Earth may have a different latitude and longitude values in different coordinate systems. For example, a stop sign at the corner Maple St. and Main St. may have a latitude and longitude of (LAT 1 , LON 1 ) in the WGS84 coordinate system, but may have a latitude and longitude of (LAT 2 , LON 2 ) in the NAD83 coordinate system (where LAT 1 ≠LAT 2  and/or LON 1 ≠LON 2 ). Thus, when comparing one geographic point to another geographic point to determine the distance between them, it is desirable to have both geographic points in the same global coordinate system. 
     Additionally, it should be appreciated that geo-location data included in electronic records may in some instances be referenced to a map-based or “projected” coordinate system. As appreciated in the relevant art, representing the curved surface of the Earth on a flat surface or plane is known as a “map projection.” Representing a curved surface in two dimensions causes distortion in shape, area, distance, and/or direction. Different map projections cause different types of distortions. For example, a projection could maintain the area of a feature but alter its shape. A map projection defines a relation between spherical coordinates on the globe (i.e., longitude and latitude in a global coordinate system) and flat planar x,y coordinates (i.e., a horizontal and vertical distance from a point of origin) in a projected coordinate system. 
     Thus, comparisons of a first geographic location expressed in x,y coordinates to a second geographic location expressed as LAT,LON coordinates in some geodetic global coordinate system also need to be considered in connection with act  607  or the process  600 . In such a situation, it is desirable to have respective coordinate pairs for the first location and the second location either in the same geodetic global coordinate system or projected coordinate system (projected from the same geodetic geographical coordinate system). As such, at act  607  of the process  600 , if the set of marking geo-location data points and the set of locate geo-location data points are in different coordinate systems, one or both of these sets of geo-location data points may be converted (e.g., transformed) so that they are in a common frame of reference (e.g., the same global coordinate system or the same projected coordinate system projected from the same global coordinate system). 
     For example, in some embodiments, one of the sets of geo-location data points may be geo-locations in the WGS84 coordinate system (i.e., the coordinate system typically used by GPS equipment), whereas the other of the sets of geo-location data points may be stored with reference to the NAD83 coordinate system. Thus, at act  607 , the coordinates from the respective data sets may be put in a common frame of reference; for example, the NAD83 coordinates may be converted to the WGS84 coordinate system, the WGS84 coordinates may be converted to the NAD83 coordinate system, or the coordinates from the respective sets may both be converted to a third common coordinate system. 
     Process  600  then continues to act  609 , where the set of marking geo-location data points are compared to the set of locate geo-location data points in the common reference frame to assess the quality of the locate and/or marking operation. A variety of different techniques may be used to compare the two sets of geo-location data points, examples of which are provided below. However, the invention is not limited to using the particular technique described in connection with  FIG. 9 , as various embodiments may use different techniques. 
     In some embodiments, an overall shape of a detected facility line as indicated by the locate geo-location data may be qualitatively compared (e.g., by visual inspection, as discussed below in Section VI) to an overall shape of a line constituted by respective locate marks dispensed during the locate and/or marking operation as represented by the marking geo-location data, irrespective of their relative geo-locations, such that quality is assessed based on how close these shapes are to each other. 
     In other embodiments, the set of marking geo-location data points may be compared to the set of locate geo-location data points to determine geographic distance between them.  FIG. 10  shows an illustrative process  1400  for determining distance between points in two sets, X and Y, of geo-location data points, that may be performed in the act  609  of process  600 . Each of these sets may include a plurality of geo-location data points (e.g., latitude and longitude values or x,y coordinate pairs), and the geo-location data points in set X typically are in the same reference frame (e.g., coordinate system) as the geo-location data points in set Y. In embodiments in which the process  1400  is used to compare a set of marking geo-location data points to a set of locate geo-location data points, set X may include the marking points and set Y may include the locate points; however, it should be appreciated that this assignment is provided primarily for purposes of illustration. Process  1400  defines the distance between the two sets X and Y as a vector d of distances d 0  . . . d n  (i.e., d=[d 0  . . . d n ]), where each distance d i  indicates distance between a point x i  in set X and the point y c  in set Y that is closest to x i . Accordingly, it should be appreciated that the vector d is indexed to the set X, and thus there is one element in the vector d for every data point in the set X. 
     Referring to  FIG. 10 , the illustrative process  1400  begins at act  1402  by initializing a variable n to zero, where n serves as an index for the points in the set X. The process  1400  continues to act  1404 , where a point x n  in the set X is selected. The process  1400  next continues to act  1406 , where a point in set Y that is closest to the point x n  is identified and is stored in a variable y c . That is, among all the points in the set Y, the selected point y c  has the smallest distance from the point x n . The process  1400  then continues to act  1408 , where a distance between x n  and y c  is recorded and stored in the variable d n . The process next continues to act  1410 , where it is determined whether there are any more points in the set X to process. When it is determined that the set X contains one or more points yet to be processed, the process  1400  continues to act  1412 , where the value of n is incremented by one. The process then returns to act  1404  to select a next point in the set X. If, on the other hand, it is determined at act  1410  that there are no more points in the set X to process, the process  1400  ends. 
     It should be appreciated that each of the sets X and Y may include any number of points, as the present disclosure is not limited in this respect. For example, in some embodiments, one or both of the sets may have only one geo-location point specifying a single point on Earth. In other embodiments, one or both sets may have multiple geo-location points specifying multiple points on Earth. 
     Additionally, the process  1400  may be applied to determine a measure of distance between any two sets of points in any space in which a measure of distance can be defined between two points. Thus, the application of the process  1400  is not limited to geo-location data expressed in an absolute frame of reference that ties the geo-location data to specific points on Earth. For example, in some embodiments, the geo-location points in set X and Y may not be expressed in latitude and longitude. Rather they may be expressed as locations (e.g., distance and/or direction) relative to some other reference point (e.g., an arbitrary reference point, a reference point defined by one or more facilities maps, and/or a reference point defined by some environmental landmark, a reference point defined by one or more physical markers placed at the work site such as property boundary markers). In some further embodiments, the process  1400  may even be applied to determine a measure of distance between two sets of points expressed in terms of display coordinates for some field of display (e.g., a computer screen). 
     The process  1400  is also not limited to any particular technique for determining the distance between two points, as any of numerous techniques may be used. For example, in an embodiment where the geo-location data is expressed in latitudinal and longitudinal coordinates, a distance between two points may be calculated according to the great-circle distance in spherical geometry, using Vincenty&#39;s inverse method for computing geographical distance between two points, and/or using some other suitable method. In some embodiments in which the coordinates for the two points are each two-dimensional Cartesian coordinates in a common grid system, the straight line distance between these two points may be determined using the following formula: d=sqrt((x 2 −x 1)   2 +(y 2 −y 1 ) 2 ). In some implementations, a geographical center of a marking may be determined and compared against a geographical center of a located facility. 
     In alternative embodiments based on the process  1400  shown in  FIG. 10 , one or both of the data sets X and Y may be processed in some manner to filter (e.g., remove, interpolate, extrapolate, smooth, curve fit) all or some portion of the data. For example, either of the data sets may include some geo-location data points that are less accurate and/or less reliable than other points in the set, and/or constitute random or spurious data points (noise) in the set. In this manner, some portion of the data set viewed as a whole may resemble a random distribution of points, and/or there may be larger gaps between some groups of points than other groups of points. In some instances, some locate geo-location data points may be less reliable than others due to variations in received signal strength at particular gain and/or frequency settings. Additionally, rapid and/or disjointed movements of a marking device and/or locate device by a technician may result in local fluctuations of the geo-location data points that are inconsistent with the overall pattern of detection and/or marking. In sum, for any of a variety of reasons, it may be desirable to process a given data set in some manner to improve one or more characteristics of the data set to facilitate a more meaningful comparison with one or more other data sets. 
     To this end, in one embodiment relating particularly to the filtering of a locate geo-location data set, a “confidence rating” may be attributed to one or more data points of the locate geo-location data set based, for example, on a reliability of the data, and one or more points of the data set may be removed based on a confidence rating that falls below some predetermined threshold. In various aspects, attributes such as gain setting, frequency setting, and signal strength (e.g., peak amplitude, null amplitude) at the time of acquiring a given locate geo-location data point may be considered, respectively or in various combinations, in deriving a confidence rating for that data point. In general, the reliability of a data point may be lower for higher gain settings (e.g., gain above 60-70% full scale, for which spurious signals may be registered that do not actually correspond to a presence of an underground facility) and/or for higher frequency settings (at which there is a higher likelihood that the locate receiver may “hop lines,” i.e., detect other nearby underground facilities but not necessarily the closest one to the locate receiver), and/or for peak/null amplitudes that are inconsistent and/or below some predetermined percentage of full scale value. 
     A confidence rating may be determined on any of a variety of scales (e.g., 0 to 100%, with 100% representing greatest reliability; 0-10, with 10 representing greatest reliability, etc.), based on any of a variety of criteria (e.g., any signal received at a gain setting of 75% full scale is assigned a confidence rating of 50%; signals received with a peak amplitude of 75% full scale at a gain setting of 50% full scale or less are assigned a confidence rating of 80%; etc.). Furthermore, various “confidence threshold values” for confidence ratings may be established as a basis for comparison for the confidence ratings; for example, a confidence threshold value may be established, and data points having a confidence rating below the confidence threshold value may be removed from the locate geo-location data set (e.g., set a confidence threshold value at 30%, such that all points with a confidence rating of 30% or below may removed from the data set). 
     In other exemplary implementations, in addition to or as an alternative to filtering of locate geo-location data based on a confidence rating, curve fitting may be employed to process a data set, in which a mathematical function (e.g., a polynomial function) is constructed to best fit the geo-location data points in the set. Curve fitting may involve interpolation, in which essentially an exact fit to the data is desired, or “smoothing,” in which an approximating function is constructed that attempts to capture important patterns in the data, while leaving out noise or other fine-scale structures. Various known algorithms may be employed for data smoothing, one common example of which includes the “moving average” algorithm. Other examples of curve fitting may employ a “spline,” which is a special function defined piecewise by polynomials (i.e., a piecewise polynomial parametric curve). Cubic splines are also referred to in the relevant arts as “Bezier curves.” A generalized class of splines is referred to in the relevant arts as “non-uniform rational basis splines” (NURBS), which offer great flexibility for handling both analytic and freeform shapes. Fitted curves can be used not only to render data sets more uniform, but also to infer values between discrete points of a data set. Extrapolation refers to the use of a fitted curve beyond the range of the data in a data set. 
     In one exemplary embodiment in which it is presumed for purposes of illustration that the data set X includes a set of discrete coordinates representing marking geo-location data and the data set Y includes a set of discrete coordinates representing locate geo-location data, the data set Y is subjected to a filtering algorithm (e.g., performed by the processor  1803  of the system  1800  shown in  FIG. 2 , executing processor-executable instructions corresponding to the filtering algorithm) so as to construct a best fit function or a smoothing function (e.g., employing various types of splines) representing the data set Y (as discussed above, the data set Y representing locate geo-location data may or may not have been “pre-filtered” based on a confidence rating or reliability factor associated with respective data points in the set). In one aspect of this embodiment, the best fit function or the smoothing function is then sampled to form a new data set Y′ of discrete data points. The sampling may be performed at any of a variety of sampling rates/intervals to render the new data set Y′. In one example, the sampling rate may be based on the number of discrete data points in the data set X, such that there is essentially (or approximately) a one-to-one correspondence between points in the data set X and points in the data set Y′; in other examples, however, significantly higher sampling rates may be employed such that the number of points in the data set Y′ exceeds the number of points in the data set X. The data set Y′ may then be employed in place of the data set Y in act  1406  of the process  1400  as outlined in  FIG. 10 . As such, the resulting distance values d 0  . . . d n  constituting the vector d may represent respective distances between each of the marking geo-location data points and a discrete version of the best fit function or the smoothing function for the set of locate geo-location data points. 
     In another aspect of this embodiment, the vector d of distance values d 0  . . . d n  may be calculated as an alternative to acts  1406  and  1408  of  FIG. 10  by using the best fit function or the smoothing function itself as a reference for comparison with the discrete marking geo-location data points of the set X. More specifically, various techniques are known for computing the minimum distance between a point and a fitted curve (e.g., see “Computing the Minimum Distance Between a Point and a NURBS Curb,” Xiao-Diao Chen et al., Computer-Aided Design, Vol. 40, Issue 10-11, Oct. 2008, pages 1051-1054; “Finding the Minimum Distance Between a Point and a Cubic Spline,” Don Lancaster, Synergetics, Thatcher, Ariz., 2007, http://www.tinaja.com/glib/cmindist.pdf; Andersson, F., “Bézier and B-spline technology,” Frederik Andersson, Master&#39;s thesis, Department of Computing Science, UMEA University (Sweden), Jun. 11, 2003; each of the three foregoing publications is incorporated herein by reference in its entirety). Any of various known techniques may be employed to compare the respective points in the set X to the best fit function or the smoothing function. Accordingly, the resulting distance values d 0  . . . d n  constituting the vector d may represent respective minimum distances between each of the marking geo-location data points and the best fit function or the smoothing function itself for the set of locate geo-location data points. 
     While in the example above filtering was applied to the set Y of locate geo-location data points, it should be appreciated that a similar filtering process may be applied to either or both of the marking geo-location data points and the locate geo-location data points for purposes of comparing marking information with locate information, and that either of filtered marking geo-location data or filtered locate geo-location data may serve as a basis of comparison with the other (whether filtered or unfiltered). 
     Referring back to  FIG. 9 , after the comparison in act  609 , the process continues to act  611 , where a quality assessment of the locate and/or marking operation that is based, at least in part, on the comparison in act  609  is generated. The quality assessment may be generated in any of a variety of ways, including, for example, in the manner discussed above in connection with act  1312  of  FIG. 8 . Several examples of techniques for generating a quality assessment are described below. However, the invention is not limited to any particular technique for generating a quality assessment. 
     In embodiments in which the process illustrated in  FIG. 10  is used to perform the comparison in act  609 , in some exemplary implementations the quality assessment may be based on the percentage of points in the distance vector d that are below (or above) some threshold value. For example, in one implementation, the quality assessment may be based on the percentage of locate marks that are within a threshold distance of any point in the locate geo-location data set, or within a threshold distance of a discrete or continuous best fit function or smoothing function representing the locate geo-location data set. 
     Table 7 below shows one possible technique for generating a quality assessment of a marking operation via comparison to locate information (or vice versa) using a scoring table. Techniques for generating a scoring table and computing a score using a scoring table are described in greater detail in U.S. Non-provisional Patent application Ser. No. 12/493,109, filed Jun. 26, 2009, entitled “Methods and Apparatus for Quality Assessment of a Field Service Operation,” incorporated by reference herein. While the examples below discuss assessment of a marking operation based on locate information serving as the reference information, as discussed above it should be appreciated that the reverse (assessing a locate operation based on marking information serving as the reference information) also is possible according to the concepts discussed herein. As shown in Table 7, the criterion on which the quality of marking operation is being assessed is listed in the leftmost column. For this criterion, the table includes one or more expected or reference values or ranges for the criterion, also referred to as “metrics,” against which information about the marking operation is measured/compared. The metrics are divided into several “scoring categories,” namely, value(s)/condition(s) that, if met, result in a particular score. 
     For purposes of the analysis illustrated in Table 7, marking information/data is referred to as ACTUAL DATA (ACT), and locate information/data is referred to as EXPECT DATA (EXP). A quality assessment for the indicated criterion is based on a comparison of the ACTUAL DATA to the EXPECT DATA (e.g., so as to determine in what scoring category the ACTUAL DATA falls as a result of the comparison). For purposes of the discussion that follows, although examples based on numeric scores are provided, the term “score” as used herein is intended to more generally denote any of a variety of graduated indicators for a quality assessment (which in turn may be based on a variety of ranges, scales and resolutions/granularity for the indicators). 
     
       
         
           
               
               
             
               
                   
                 TABLE 7 
               
             
            
               
                   
                   
               
               
                   
                 Expected value or range (metrics) 
               
            
           
           
               
               
               
               
            
               
                 Criterion 
                 Preferred 
                 Marginal 
                 Unacceptable 
               
               
                   
               
               
                 EXP: Percentage of 
                 75% or more 
                 Less than 75% 
                 50% or more 
               
               
                 points in distance 
                 of points 
                 of points are 
                 of points 
               
               
                 vector within 
                 are within 
                 within 1 foot, 
                 are outside 
               
               
                 threshold distance 
                 1 foot. 
                 but 50% or more 
                 2 foot. 
               
               
                   
                   
                 of points are 
               
               
                   
                   
                 within 2 feet. 
               
               
                 ACT: Percentage of 
                 90% of 
               
               
                 points in distance 
                 points are 
               
               
                 vector within 
                 within 
               
               
                 threshold distance 
                 1 foot. 
               
               
                   
               
            
           
         
       
     
     In the example of Table 7, the criterion on which the quality of the marking operation is being assessed is the percentage of points at which locate marks were placed that are within some threshold distance of the closest corresponding point in the locate geo-location data, or within some threshold distance of a discrete or continuous best fit function or smoothing function for the locate geo-location data. Additionally, in this example, there are three scoring categories: Preferred; Marginal; and Unacceptable. For each scoring category, there is a metric used to evaluate the contents of the distance vector d=[d 0  . . . d n ] resulting from the comparison of the marking data and the locate data to determine in which scoring category the results of the comparison fall. In the example of Table 7, an evaluation of the distance vector shows that 90% of the points at which locate marks were placed were within one foot of the corresponding closest point in the locate data (or the discrete or continuous best fit function or smoothing function for the locate geo-location data). As such, the marking operation falls into the preferred category. 
     The data of Table 7 may correspond, as an example, to a marking operation as depicted in  FIG. 11 . In  FIG. 11 , the set “X” of points is denoted with the reference numeral  1620  and includes marking geo-location data points (provided, for purposes of illustration, as x,y coordinates) and the set “Y” of points is denoted with the reference numeral  1610  and includes locate geo-location data points (also provided as x,y coordinates) representing detected locations of an underground facility  1660 . Additionally, the line  1630  represents an example of a best fit function for the locate geo-location data points. As can be seen in  FIG. 11 , 90% of the points in the set  1620  lie within 1 foot of the detected facility, as represented in Table 7. 
     With reference again to act  611  of  FIG. 9 , in some embodiments a score, grade, or categorization may be assigned as an output to categorize the quality assessment process based on into which scoring category the assessment falls. For example, in some embodiments, each scoring category may be associated with a number of points (e.g., 2 points for Preferred, 1 point for Marginal, and 0 points for Unacceptable), and the quality assessment may be awarded the number of points associated with the scoring category into which it falls. Thus, for example, in the example of Table 7, 2 points may be awarded, because the operation falls in the “Preferred” scoring category. 
     In some embodiments, the number of points awarded may be converted to a percent score that is based on the number of points awarded and a maximum possible number of points. Thus, for example, in the example of Table 7, the marking operation received two points out of a maximum possible two points. As such, the marking operation may be assigned a score of 2/2 or 100%. If the assessment results were to fall in the “Marginal” category and receive only one point, then the marking operation may be assigned a score of ½ or 50%. Similarly, if the assessment results were to fall in the unacceptable category and receive zero points, then it may be assigned a score of 0/2 or 0%. 
     In some embodiments, a range of percent scores may be converted to letter scores to provide an indication of quality. For example, a percent score of 100-90% may be converted to a letter score of A, 89-80% may be converted to a letter score of B, 79-70% may be converted to a letter score of C, 69-60% may be converted to a letter score of D, and &lt;60% may be converted to a letter score of F. In yet another example, a range of percent scores may be converted to a simple PASS/FAIL score. For example, a percent score of 100-60% may be converted to a score of PASS and a percent score of &lt;60% may be converted to a score of FAIL. 
     In some embodiments, the quality assessment illustrated in Table 7 may be used in the process of  FIG. 8  or  9  to categorize a marking operation as either “Approved,” “Coach” or “QC Referral. For example, data analysis as depicted in Table 7 may be used to assess the quality of the marking operation. Based on this assessment, the quality of the marking operation may be categorized, for example at act  1314  of  FIG. 8 . For example, if the operation falls in the “Preferred” scoring category in Table 7 it may be categorized as “Approved”; if the operation falls in the “Marginal” scoring category, it may be categorized as “Coach;” and if the operation falls in the “Unacceptable” scoring category it may be categorized as “QC Referral.” 
     In the example of Table 7, three scoring categories are used, such that the marking operation is classified as either Preferred, Marginal, and Unacceptable. However, the number of scoring categories is merely illustrative, as any number of scoring categories could be used, and various mutually exclusive metrics may be assigned to these scoring categories. For example, in some embodiments, five scoring categories may be used (e.g., Excellent, Good, Average, Poor, Unacceptable), while in other embodiments more than five scoring categories may be used. 
     In addition, it should be appreciated that the percentage values and distance threshold values used in the metrics in Table 7 (and in Tables 8 and 9 described below) are merely illustrative and that a variety of different percentage values and distance threshold values may be used. In some embodiments, the distance threshold values may be based on legal requirements pertaining to locate and/or marking operations. For example, some governments (e.g., state governments) may dictate that a locate mark placed on the ground is within a certain “tolerance zone” around the underground facility (e.g., 12 inches, 18 inches, 24 inches, 30 inches, 36 inches, etc.). Thus, in some embodiments, one or more of the metrics used in a scoring table may be based on a tolerance zone dictated by government regulations. 
     In the example provided by Table 7, a single criterion is provided for all of the facility lines marked. However, in some embodiments, a separate criterion may be used for each facility line marked. For example, as shown in Table 8 below, if during a marking operation, a gas line, a power line, and a water line were marked, then a separate criterion may be provided for each of these facility lines. This enables the accuracy of each facility line that was marked during the locate and/or marking operation to be assessed independently of the other facility lines. 
     As discussed above, in some embodiments, each scoring category may be associated with a number of points (e.g., 2 points for Preferred, 1 point for Marginal, and 0 points for Unacceptable), and the quality assessment may be awarded the number of points associated with the scoring category into which it falls. Thus, for example, in the example of Table 8, 2 points may be awarded for marking of the gas line(s), 1 point may be awarded for the marking of the electric line(s), and 0 points may be awarded for the marking of the water line(s). Thus, the operation may receive a score of three points out of a maximum possible total of six points, for a score of 3/6 or 50%. 
     In the example provided by Table 7 for generating a quality assessment of the marking operation, the sole criterion for assessing quality may be based on a comparison of the marking geo-location data representative of marks placed during a locate and/or marking operation and the locate geo-location data representative of one or more facilities detected during one or more current or historical locate operations. However, the invention is not limited in this respect, as in some embodiments, this criterion may be one of a number of criteria that is used at act  611  of  FIG. 9  to generate/update a quality assessment. There are variety of techniques by which this criterion may be used in combination with other criteria to generate a quality assessment, one example of which is provided below. However, the invention is not limited to using the particular technique described below or any other particular technique. 
     
       
         
           
               
               
             
               
                   
                 TABLE 8 
               
             
            
               
                   
                   
               
               
                   
                 Expected value or range (metrics) 
               
            
           
           
               
               
               
               
            
               
                 Criterion 
                 Preferred 
                 Marginal 
                 Unacceptable 
               
               
                   
               
               
                 EXP: Type = Gas; 
                 95% or more 
                 Less than 95% 
                 50% or more 
               
               
                 Percentage of 
                 of points 
                 of points are 
                 of points 
               
               
                 points within 
                 are within 
                 within 1 foot, 
                 are outside 
               
               
                 threshold distance 
                 1 foot. 
                 but 50% or more 
                 2 feet. 
               
               
                 of any facility 
                   
                 of points are 
               
               
                 line point (as 
                   
                 within 2 feet. 
               
               
                 indicated in 
               
               
                 historical 
               
               
                 reference data) 
               
               
                 ACT: Type = Gas; 
                 98% of 
               
               
                 Percentage of 
                 points are 
               
               
                 points within 
                 within 1 
               
               
                 threshold distance 
                 foot. 
               
               
                 of any facility 
               
               
                 line point (as 
               
               
                 indicated in 
               
               
                 historical 
               
               
                 reference data) 
               
               
                 EXP: Type = Electric; 
                 95% or more 
                 Less than 95% 
                 50% or more 
               
               
                 Percentage of 
                 of points 
                 of points are 
                 of points 
               
               
                 points within 
                 are within 
                 within 1 foot, 
                 are outside 
               
               
                 threshold distance 
                 1 foot. 
                 but 50% or more 
                 2 feet. 
               
               
                 of any facility 
                   
                 of points are 
               
               
                 line point (as 
                   
                 within 2 feet. 
               
               
                 indicated in 
               
               
                 historical 
               
               
                 reference data) 
               
               
                 ACT: Type = Electric; 
                   
                 10% of points 
               
               
                 Percentage of 
                   
                 are outside of 
               
               
                 points within 
                   
                 1 foot, but 75% 
               
               
                 threshold distance 
                   
                 of points are 
               
               
                 of any facility 
                   
                 within 2 feet. 
               
               
                 line point (as 
               
               
                 indicated in 
               
               
                 historical 
               
               
                 reference data) 
               
               
                 EXP: Type = Water; 
                 95% or more 
                 Less than 95% 
                 50% or more 
               
               
                 Percentage of 
                 of points 
                 of points are 
                 of points 
               
               
                 points within 
                 are within 
                 within 1 foot, 
                 are outside 
               
               
                 threshold distance 
                 1 foot. 
                 but 50% or more 
                 2 feet. 
               
               
                 of any facility 
                   
                 of points are 
               
               
                 line point (as 
                   
                 within 2 feet. 
               
               
                 indicated in 
               
               
                 historical 
               
               
                 reference data) 
               
               
                 ACT: Type = Water; 
                   
                   
                 80% of 
               
               
                 Percentage of 
                   
                   
                 points are 
               
               
                 points within 
                   
                   
                 outside 
               
               
                 threshold distance 
                   
                   
                 1 foot. 
               
               
                 of any facility 
               
               
                 line point (as 
               
               
                 indicated in 
               
               
                 historical 
               
               
                 reference data) 
               
               
                   
               
            
           
         
       
     
     In some embodiments, a scoring table, similar to Table 7 may be used to assess the quality of a locate and/or marking operation based on a plurality of different criteria. An example of such a scoring table is shown below in Table 9. Table 9 is similar to Table 7, except that instead of a single criterion in the left-most column, there are multiple criteria. In addition, in Table 9, each criterion may be assigned a weight factor, such that some criteria (e.g., criteria that are deemed more important) may optionally be given greater weight than others in the quality assessment. As with Table 7, for each criterion in Table 9, actual data (field data) obtained from the locate and/or marking operation being evaluated may be compared with expected data (reference data) values or ranges for that criterion, and a number of points may be awarded based on the scoring category into which the locate and/or marking operation falls for that criterion and a weight factor assigned to that scoring category. For example, if the weight factor for a particular criterion is 5 and the marking operation falls into the “Preferred” category for that criterion, then 10 points (i.e. 2×5) would be awarded for that criterion based on the example given above in connection with Table 7. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 9 
               
             
            
               
                   
                   
               
               
                   
                 Expected value or range 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Preferred 
                 Marginal 
                 Unacceptable 
                 Weight 
                 Weighted 
               
               
                 Criterion 
                 (score = 2) 
                 (score = 1) 
                 (score = 0) 
                 Factor 
                 Score 
               
               
                   
               
               
                 EXP: Percentage of points 
                 75% or more of points are 
                 Less than 75% of points 
                 50% or more of 
                 — 
                 — 
               
               
                 in distance vector within 
                 within 5 feet. 
                 are within 5 feet, but 
                 points are 
               
               
                 threshold distance 
                   
                 50% or more of points 
                 outside 10 feet. 
               
               
                   
                   
                 are within 10 feet. 
               
               
                 ACT: Percentage of points 
                 90% of points are 
                   
                   
                 x1 
                 2 
               
               
                 in distance vector within 
                 within 5 feet. 
               
               
                 threshold distance 
               
               
                 EXP: Dig area geo-location 
                 N35°43.57518, 
                 N35°43.57518, 
                 N35°43.57518, 
                 — 
                 — 
               
               
                   
                 W078°49.78314 ≦0.2 miles 
                 W078°49.78314 &gt;0.2 
                 W078°49.78314 &gt;0.5 miles 
               
               
                   
                   
                 to ≦0.5 miles 
               
               
                 ACT: Geo-location data 
                 N35°43.57518, 
                   
                   
                 P/F 
                 P 
               
               
                   
                 W078°49.78314 ± 0.04 mi 
               
               
                 EXP: Locate Date 
                 Before 05FEB09 
                 On 05FEB09 
                 After 05FEB09 
                 — 
                 — 
               
               
                 ACT: Timestamp data 
                 04FEB2009; 09:35:15.2 
                   
                   
                 x2 
                 4 
               
               
                 EXP: Elapsed time 
                 40 mins 
                 40 mins ± 10-20 mins 
                 40 mins ± &gt;20 mins 
                 — 
                 — 
               
               
                 ACT: Timestamp data 
                   
                 54 mins 
                   
                 x2 
                 2 
               
               
                 EXP: Type = Electric power 
                 RED color data present 
                 n/a 
                 RED color data absent 
                 — 
                 — 
               
               
                 ACT: Color data 
                 RED present 
                   
                   
                 x5 
                 10  
               
               
                 EXP: Geo-location 
                 N35°43.57518, 
                 N35°43.57518, 
                 N35°43.57518, 
                 — 
                 — 
               
               
                   
                 W078°49.78314 ± 0 to 0.1 mi 
                 W078°49.78314 ± &gt;0.1 
                 W078°49.78314 ± &gt;0.2 mi 
               
               
                   
                   
                 to &lt;0.2 mi 
               
               
                 ACT: Geo-location data 
                 N35°43.57518, 
                   
                   
                 x2 
                 4 
               
               
                   
                 W078°49.78314 ± 0.04 mi 
               
               
                 EXP: Gain 
                 0-45 
                 &gt;45-70 
                 &gt;70-100 
               
               
                 ACT: Gain 
                 35 
                   
                   
                 x1 
                 2 
               
               
                 EXP: Sig. strength 
                 100-85% 
                 &lt;85-65% 
                 &lt;65% 
                 — 
                 — 
               
               
                 ACT: Signal data 
                   
                 83% 
                   
                 x1 
                 1 
               
               
                 EXP: Type = Gas, oil 
                 YELLOW color data absent 
                 n/a 
                 YELLOW color data present 
                 — 
                 — 
               
               
                 ACT: Color data 
                 YELLOW absent 
                   
                   
                 x5 
                 10  
               
               
                 EXP: Type = Com, CATV 
                 ORANGE color data absent 
                 n/a 
                 ORANGE color data present 
                 — 
                 — 
               
               
                 ACT: Color data 
                 ORANGE absent 
                   
                   
                 x5 
                 10  
               
               
                 EXP: Type = Water 
                 BLUE color data present 
                 n/a 
                 BLUE color data absent 
                 — 
                 — 
               
               
                 ACT: Color data 
                 BLUE present 
                   
                   
                 x5 
                 10  
               
               
                 EXP: Geo-location 
                 N35°43.57518, 
                 N35°43.57518, 
                 N35°43.57518, 
                 — 
                 — 
               
               
                   
                 W078°49.78314 ± 0 to 0.1 mi 
                 W078°49.78314 ± &gt;0.1 
                 W078°49.78314 ± &gt;0.2 mi 
               
               
                   
                   
                 to &lt;0.2 mi 
               
               
                 ACT: Geo-location data 
                   
                 N35°43.57518, 
                   
                 x2 
                 2 
               
               
                   
                   
                 W078°49.78314 ± 0.14 mi 
               
               
                 EXP: Gain 
                 0-45 
                 &gt;45-70 
                 &gt;70-100 
               
               
                 ACT: Gain 
                 35 
                   
                   
                 x1 
                 2 
               
               
                 EXP: Sig. strength 
                 100-85% 
                 &lt;85-65% 
                 &lt;65% 
                 — 
                 — 
               
               
                 ACT: Signal data 
                 87% 
                   
                   
                 x1 
                 2 
               
               
                 EXP: Type = Sewer 
                 GREEN color data absent 
                 n/a 
                 GREEN color data present 
                 — 
                 — 
               
               
                 ACT: Color data 
                 GREEN absent 
                   
                   
                 x5 
                 10  
               
               
                 EXP: Type = Irrigation 
                 PURPLE color data absent 
                 n/a 
                 PURPLE color data present 
                 — 
                 — 
               
               
                 ACT: Color data 
                 PURPLE absent 
                   
                   
                 x5 
                 10  
               
               
                 EXP: Locate technician ID 
                 Lookup table 
                 n/a 
                 Not found 
               
               
                 ACT: Locate technician ID 
                 4815 
                   
                   
                 P/F 
                 P 
               
               
                 EXP: Marking Device ID 
                 Lookup table 
                 n/a 
                 Not found 
               
               
                 ACT: Marking Device ID 
                 7362 
                   
                   
                 P/F 
                 P 
               
               
                 EXP: Locate Device ID 
                 Lookup table 
                 n/a 
                 Not found 
               
               
                 ACT: Locate Device ID 
                 7345 
                   
                   
                 P/F 
                 P 
               
               
                 EXP: Temp (°F.) 
                 50-80 
                 20-&lt;50, &gt;80-110 
                 &lt;20, &gt;110 
                   
                 — 
               
               
                 ACT: Temp data 
                 73 F. 
                   
                   
                 x2 
                 4 
               
               
                 EXP: Humidity 
                 0-40% 
                 &gt;40-90% 
                 &gt;90-100% 
                 — 
                 — 
               
               
                 ACT: Humidity data 
                   
                 52% 
                   
                 x2 
                 2 
               
               
                 EXP: Light 
                 4.0 to 5.0 volts 
                 2.0 to &lt;4.0 volts 
                 &lt;2.0 volts 
                 — 
                 — 
               
               
                 ACT: Light data 
                 4.3 volts 
                   
                   
                 x2 
                 4 
               
               
                 EXP: Inclinometer 
                 −30 to 30 degrees 
                 &lt;−30 to −60 degrees 
                 &lt;−60 to −90 degrees 
                 — 
                 — 
               
               
                   
                   
                 or &gt;30 to 60 degrees 
                 or &gt;60 to 90 degrees 
               
               
                 ACT: Inclinometer data 
                 −17 
                   
                   
                 x1 
                 2 
               
               
                 EXP: Accelerometer data 
                 0.2 g to 1.0 g 
                 &gt;1.0 g to 1.5 g 
                 &gt;1-5 g 
                 — 
                 — 
               
               
                 ACT: 
                 0.375 g 
                   
                   
                 x1 
                 2 
               
               
                 EXP: Battery strength data 
                 100-85% 
                 &lt;85-50% 
                 &lt;50% 
                 — 
                 — 
               
               
                 ACT: Battery strength data 
                 93% 
                   
                   
                 x5 
                 10  
               
            
           
           
               
               
            
               
                 Total points earned out of a possible 112 = 
                 105  
               
               
                 Percent Score = 
                 93.8% 
               
               
                   
               
            
           
         
       
     
     Once the number of points awarded for each criterion has been determined, a total number of points may be computed by summing together the points awarded for each of the criteria together. The maximum number of points possible for the locate and/or marking operation may be determined by first determining the sum of all weight factors and then multiplying this sum by the point value of the “Preferred” result. A percentage score may be determined by dividing the number of points awarded by the maximum number of points possible and multiplying the result by 100. 
     For example and referring to Table 9, the sum of the weight factors is 56 and the point value of the “Preferred” result is 2. Therefore, in this example the maximum number of points possible for the locate operation is 56×2, which is 112. The sum of the points earned for the current locate operation, in the example of Table 9, is 105. Thus, the percent score for the current locate operation, which in this example is 105/112×100=93.8%. 
     As discussed above, a range of percent scores may be converted to letter scores, so that a letter score letter score indicative of the quality of the locate and/or marking operation may be assigned. For example, a percent score of 100-90% may be converted to a letter score of A, 89-80% may be converted to a letter score of B, 79-70% may be converted to a letter score of C, 69-60% may be converted to a letter score of D, and &lt;60% may be converted to a letter score of F. In yet another example, a range of percent scores may be converted to a simple PASS/FAIL score. For example, a percent score of 100-60% may be converted to a score of PASS and a percent score of &lt;60% may be converted to a score of FAIL. 
     In other embodiments, the numerical quality assessment score may be used to automatically categorize a locate operation as either APPROVED, COACH, or QC Referral. In one example, using the numeric scoring system of 0 to 100%, a score of 60% or below may automatically render an assessment of QC Referral, in which case, for example after act  1314  of  FIG. 8 , the process continues to act  1322 . A score of &gt;60% to 80% may automatically render an assessment of COACH, in which case the process continues to act  1318 , and a score of &gt;80% to 100% may automatically render an assessment of APPROVED. 
     The example of Table 9 depicts a scoring table have a number of various different criteria. The number of criteria and the particular criteria used are merely illustrative, as any number or type of criteria may be used. Thus, the constructs provided by Tables 7-9 above illustrate various concepts germane to assessing the quality of locate and/or marking operations based at least on reference information derived from geo-location data representative of at least one facility position (e.g., geo-location data measured in a current locate and/or marking operation or measured in a prior locate and/or marking operation), which reference information may be used alone or in combination with other information that may provide for a variety of criteria by which such operations may be assessed. 
     VI. Visual Representations 
     In some embodiments, as discussed above, any of the field information and reference information available to the assessment process from any of a variety of sources (e.g., marking information including marking geo-location data, and locate information including locate geo-location data) may be visually rendered in a display field (e.g., of a display coupled to the system  1800  shown in  FIG. 2 ) to provide a visual aid in connection with an assessment process. A visual representation may appear, at least in part, as depicted in  FIG. 11 . In some exemplary implementations, electronic visual renderings may be provided by an EM (electronic manifest) application, as discussed above. According to one aspect of this embodiment, it is particularly instructive as a visual aid to “overlay” some or all of the contents of the field information with that of the reference information in the display field, so as to provide a visual comparison of the information (e.g., as a supplement to the automated/electronic comparison of various elements of the available field and reference information). To aid in such a comparison, different facility types may be indicated in the display field, for example, by employing different colors or line types, and different environmental landmarks may be indicated in the display field, for example, by employing different colors, shapes, patterns, icons, etc. 
       FIG. 12  illustrates a perspective view of an overlay  1700  of a visual rendering  1702  of a marking operation on a visual rendering  1705  of a locate operation to provide a user with a visual picture of where locate marks were dispensed relative to the detected locations of facility lines, according to one embodiment. From the overlay  1700 , a viewer may obtain an “at-a-glance” qualitative view of the marking information as compared to the locate information. For example, in  FIG. 12 , the visual rendering  1702  or the marking operation includes: 1) a lines pattern  1716  correlated to telecommunications line  1756  of the visual rendering  1705  of the locate operation; 2) a lines pattern  1712  correlated to sewer line  1752 ; 3) a lines pattern  1714  correlated to telecommunications line  1754 ; and 4) a lines pattern  1710  correlated to power line  1750 . Overlay  1700  of  FIG. 12  is an example of a comparison that illustrates significant correspondence between the marking operation and the locate operation (i.e., substantially no discrepancies between the marking geo-location data and the locate geo-location data). However, those skilled in the art will recognize that discrepancies may occur. In such situations, the overlay of the locate marks for a particular facility line may be displaced from the detected location of the facility line. 
     More specifically, various techniques may be employed to assist the human user in making the visual comparisons of marking information and locate information. For example, the information used to render line patterns may be suitably filtered, interpolated, smoothed or otherwise processed, as discussed above, to enhance the appearance of the line patterns. Additionally, features corresponding to marking data and features corresponding to locate data may be differentiated in a display field in any of a variety of manners (e.g., different line types, symbols or patterns; different colors or shades of related colors; different vertical planes of display, etc.) to allow for visual perception of both the marking data and the locate data. 
     To further facilitate visual observations of available information from electronic renderings, in one embodiment, each of the marking information/data and the locate information data, if present in a computer-aided visual rendering, as well as any constituent information forming part of the marking data and the locate data, may be displayed as separate “layers” of the visual rendering, such that a viewer of the visual rendering may turn on and turn off displayed data based on a categorization of the displayed data. For example, some or all marking data may be categorized generally under one layer designation (e.g., “Marking”), and independently enabled or disabled for display (e.g., hidden) accordingly. Similarly, all locate data may be categorized generally under another layer designation (e.g., “Locate”) and independently enabled or disabled for display accordingly. Respective layers may be enabled or disabled for display in any of a variety of manners; for example, in one implementation, a “layer directory” or “layer legend” pane may be included in the display field (or as a separate window selectable from the display field of the visual rendering), showing all available layers, and allowing a viewer to select each available layer to be either displayed or hidden, thus facilitating comparative viewing of layers. 
     Furthermore, any of the above-mentioned general categories for layers may have sub-categories for sub-layers, such that each sub-layer may also be selectively enabled or disabled for viewing by a viewer. For example, under the general layer designation of “Marking,” different facility types that may have been marked (and indicated in the marking data by color, for example) may be categorized under different sub-layer designations (e.g., “Marking—Electric;” “Marking—Gas;” etc.); in this manner, a viewer may be able to hide the electric marking data while viewing the gas marking data, or vice versa, in addition to having the option to view or hide all marking data. Sub-layer designations similarly may be employed for the locate data (e.g., “Locate—water/sewer;” “Locate—CATV”). Virtually any characteristic of the information available for display may serve to categorize the information for purposes of displaying layers or sub-layers. 
     VII. Conclusion 
     In sum, information relating to a marking operation (e.g., marking information) may be compared to a variety of reference information for purposes of assessing a quality of the marking operation. The types of reference information may include geographic information, facility type information, landmark information, and/or other information relating to the facilities identified during a current or prior locate operation (e.g., locate information). For example, the comparison may generally involve determining whether there is agreement between data representative of a marking operation and data representative of one or more sets of corresponding reference information (e.g., locate information), and may further comprise identifying at least one correspondence or discrepancy between the compared data, and in some instances a degree of correspondence. 
     While various inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure. 
     The above-described embodiments can be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers. 
     Further, it should be appreciated that a computer may be embodied in any of a number of forms, such as a rack-mounted computer, a desktop computer, a laptop computer, or a tablet computer. Additionally, a computer may be embedded in a device not generally regarded as a computer but with suitable processing capabilities, including a Personal Digital Assistant (PDA), a smart phone or any other suitable portable or fixed electronic device. 
     Also, a computer may have one or more input and output devices. These devices can be used, among other things, to present a user interface. Examples of output devices that can be used to provide a user interface include printers or display screens for visual presentation of output and speakers or other sound generating devices for audible presentation of output. Examples of input devices that can be used for a user interface include keyboards, and pointing devices, such as mice, touch pads, and digitizing tablets. As another example, a computer may receive input information through speech recognition or in other audible format. 
     Such computers may be interconnected by one or more networks in any suitable form, including a local area network or a wide area network, such as an enterprise network, and intelligent network (IN) or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol and may include wireless networks, wired networks or fiber optic networks. 
     The various methods or processes outlined herein may be coded as software that is executable on one or more processors that employ any one of a variety of operating systems or platforms. Additionally, such software may be written using any of a number of suitable programming languages and/or programming or scripting tools, and also may be compiled as executable machine language code or intermediate code that is executed on a framework or virtual machine. 
     In this respect, various inventive concepts may be embodied as a computer readable storage medium (or multiple computer readable storage media) (e.g., a computer memory, one or more floppy discs, compact discs, optical discs, magnetic tapes, flash memories, circuit configurations in Field Programmable Gate Arrays or other semiconductor devices, or other non-transitory medium or tangible computer storage medium) encoded with one or more programs that, when executed on one or more computers or other processors, perform methods that implement the various embodiments of the invention discussed above. The computer readable medium or media can be transportable, such that the program or programs stored thereon can be loaded onto one or more different computers or other processors to implement various aspects of the present invention as discussed above. 
     The terms “program” or “software” are used herein in a generic sense to refer to any type of computer code or set of computer-executable instructions that can be employed to program a computer or other processor to implement various aspects of embodiments as discussed above. Additionally, it should be appreciated that according to one aspect, one or more computer programs that when executed perform methods of the present invention need not reside on a single computer or processor, but may be distributed in a modular fashion amongst a number of different computers or processors to implement various aspects of the present invention. 
     Computer-executable instructions may be in many forms, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments. 
     Also, data structures may be stored in computer-readable media in any suitable form. For simplicity of illustration, data structures may be shown to have fields that are related through location in the data structure. Such relationships may likewise be achieved by assigning storage for the fields with locations in a computer-readable medium that convey relationship between the fields. However, any suitable mechanism may be used to establish a relationship between information in fields of a data structure, including through the use of pointers, tags or other mechanisms that establish relationship between data elements. 
     Also, various inventive concepts may be embodied as one or more methods, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments. 
     All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. 
     The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” 
     The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. 
     As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law. 
     As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc. 
     In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.