【正文】 lenge became how to present the data in a graphical format for a preliminary review and then to identify and select the relatively small number of key records needed to calculate activity times. A preliminary review is necessary for the user to evaluate the data to determine in which activities the truck was engaged and the location of each activity.Graphical data representations and knowledge of the projectare the most appropriate sources from which to gather this information. The areas in which earthmoving activities were performed can be determined based on knowledge of the project and a plan view of the data. The truck from which the sample data were obtained moved material from two separate loading areas to two separate dumping areas.Fig. 3 shows that the truck was engaged in three separate operations, the first two of which are of importance (a single cycle of the third operation was performed and is therefore of little importance). Five loads were hauled approximately 800 m between 10:20 and 11:30 in the first operation, and a second hauling operation hauled 36 loads a distance of approximately 100 m between 10:30 and 20:20.Therefore, 2 load and haul operations consisting of 4 activities (load, haul, dump, and return) each were identified from the preliminary review. The activitynaming convention adopted for this work is the activity name followed by the associated areas. For example, loading in area 3 is labeled Load 3, while hauling from load area 1 to dump area 2 is labeled Haul 12. The TIMs were applied to the data to identify the beginning and end times for each of the identified activities.The dump activities occur in fixed locations and with zero velocity, and therefore 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。Reduction of ShortInterval GPS Data for Construction Operations AnalysisJohn Hildreth, 。 those produced by queuing can be identified as those preceding another result at approximate same time.EXTIM identified 150 records that marked the start and stop of the load activities. Further review and reduction by the user of the identified records resulted in 84 key records. This level of reduction from 18,850 to 84 records is very similar to that of the ADTIM and represents a greater than % reduction.FBTIM was used to identify the records key to the haul and return activities. The duration of the haul and return activities can be characterized as the time required for the truck to travel through or between FBTIM areas. For purposes of illustration, the FBTIM areas will be applied in both manners and are presented in Fig. 6. The truck traveled through boundary number 1 during thefirst operation and between boundaries 2 and 3 during the second operation.Further manual reduction of the data resulting from the TIMs may be necessary to produce a set of critical records. Overlapping areas can be defined for the FBTIM and produce results that are both accurate and useful. It is important to understand that the results produced may also overlap, and the appropriate overlapping results should be neglected.Data reduction by FBTIM reduced the number of records from 18,850 to 202. Further review and reduction by the user resulted in the identification of 164 key records that mark the start and stop of activities. These 164 records represent less than 1% of the total number of data records collected。 and Julio Martinez, Abstract: The systems that historically have been used to collect data for time studies of construction operations are manual in nature and limited to the observer39。 position of the truck must be within a userdefined area。 Data analysis。 points in gray indicate velocity was zero, and those in black indicate velocities greater than zero.Time is of paramount interest from the data, and yet the most straightforward graphic, the plan view, does not contain time information. Therefore, a graph of position when velocity was zero versus time is also prepared to aid in understanding the data. The distance to a fixed point is used to represent the 2D position by a single value. The point can be arbitrarily chosen, but for load and haul operations, choosing the approximate center of the loading area will provide additional meaning to the graph by allo