【正文】 ore the ADTIM was used to identify the records key to those activities. The ADTIM areas to be applied to the data are shown in Fig. 5. The user can determine the central coordinates and radial distance of each ADTIM area from the plan view of the recorded data. Once the input data are provided,the ADTIM is executed and the results are placed on an ADTIM sheet. A portion of the ADTIM results for the Dump 2 activity are provided in Table 2.The results obtained should be pared with the preliminary review results to verify the ADTIM process and ensure that the total instances and time frame of the associated activities concur with the results of the preliminary review. A total of approximately 18,850 data records were collected and analyzed. The set of records where velocity equaled zero numbered approximately 13,900, a reduction of approximately 25%. Further reduction by ADTIM identified 90 key records that mark the start and end of activities. These 90 records represent less than % of the total records collected, and thus the collected data were reduced by more than %.The EXTIM was used to identify the records key to the load activities because the area in which the truck was loaded changed over time. The data file recorded on the loader was used with a critical distance of 20 m. This distance was selected based on previous experience with data from the same or similar operations.It is also necessary to review the EXTIM results to identify and eliminate any extraneous results. Such results can be produced by actions occuring outside of time frames identified during data evaluation and by trucks queuing at the loader at a distance less than the specified critical distance. Results outside an operational time frame are easily identified。 spent with velocity equal to zero within a fixed distance of a moving location—., a haul truck loading at a loader。s field of view. Global Positioning System (GPS) technology incorporated into an onboard instrumentation system can be used to autonomously collect position and velocity data without the field of view limitation. Data must be collected at a short time interval to provide the level of detail necessary for operations analysis. Thus the issue bees managing the data and identifying the relatively key records that mark the start and stop of activities. A field observer identifies the key times in real time withinstantaneous decisions of when one activity stops and the next starts based on enormous volumes of visual information. This work developed a methodology for making equivalent decisions based on GPS data and presents the procedures developed to identify the key records necessary to calculate activity durations. A case study is used to illustrate application of the system to an earthmoving operation. Also, it is postulated how the information can be used in discrete event simulation. DOI: (ASCE)07339364(2005)131:8(920)CE Database subject headings: Geographic information systems。 Construction industry。and required to travel through or between fixed areas—.,a haul truck traveling between load and dump areas. Time identification modules (TIMs) were developed to identify the GPS data records corresponding to the beginning and end of activities associated with each of the three specific modules have been developed in the VBA language for execution in Excel. The results produced by TIMs have been pared to those produced by a PAVIC+ analysis of the videotaped operation in an effort to validate the TIMs results. The activity durations resulting from both analyses were pared and found to be in agreement,both in the duration of activities and the order in which they occurred. It was concluded that the shortinterval GPS data can be reduced to the key records using the TIMs.Arrive and Depart Time Identification ModuleThe duration of certain construction activities that repeatedly occur in a fixed location can be characterized as the time elapsed while the vehicle was stopped within a given distance from a fixed point. A truck loaded from a hot mix asphalt bin or a truck dumping into the bin of a rock crusher are examples of such activities. The Arrive and Depart Time Identification Module (ADTIM) was developed for this condition and to identify the first (arrive) and last (depart) times at which the truck was stopped within a given distance of a userdefined point. The time difference between arriving and departing represents the activity duration.Three criteria must be satisfied for a record to be considered as an arrival or departure time: recorded velocity must be zero (., the truck is stopped)。and previous record must be outside the area for arrival times, or the next record must be outside the area for departure times.The ADTIM evaluates each of the three criteria in the order in which they were presented. To ensure that the recorded velocity was zero, all calculations are performed on a v=0 worksheet that contains only those records where velocity equaled zero.The user defines the area within which the truck was stopped by providing a set of central coordinates and a radial distance on the ADTIM input form, shown in Fig. 4. The user may define as many as five ADTIM areas.The third criterion is evaluated within the software. For each defined area, each position recorded with zero velocity is used to calculate a distance between the truck and the defined point. This calculated distance is pared to the usersupplied critical distance to determine if the truck is within the defined area, and each record is marked appropriately. The records are then checked again to identify changes in truck status, and those records corresponding to arrive and depart times are marked with the time at which the position was recorded.External Data Time Identification Module Some earthmoving activities do not always occur in the same location, but rather occur relative to a second location that moves over time, f