1. Scope
Two forms of ITS travel monitoring data will be covered: 1.Traffic stream characteristics measured by roadway equipment. To include, but not limited to: volume, speed, occupancy, headway, density, and vehicle classification. 2.Travel time data measured by vehicle probes and personal devices (e.g., cell phones, satellite tracking). Data Dictionary for Archiving ITS-Generated Traffic Monitoring Data This section of the Standard will be in the form of a standard specification. The Standard will cover both metadata and supporting data to describe adequately the collection, processing, and storage of primary data elements. (Primary data elements are those collected by the ITS sources supporting the archive.) Metadata will include not only the attributes of data elements specified in IEEE P1489 but additional metadata that may be necessary. Maintenance of metadata and supporting data will be covered. The elements in the data dictionary will cover such aspects of the processing of archived data as: Data measurement status: indicates how directly the data element relates to measured conditions. Possible categories include: (1) Measured data: data measured directly by collection equipment (2) Aggregated data: simple summaries of category {1} (e.g. annual average daily traffic) (3) Transformed/computed data: data that have been combined with other data or subjected to a methodology (e.g., highway capacity, congestion indices, and equivalent single-axle loads) Initial collection source: the source of the data as collected by the initial ITS equipment, including make and model of equipment. Data quality control procedure: the type of editing/quality control used to process the data. Data quality control results: the results of the data editing/quality control (e.g., error flags). Data imputation/replacement: any imputation used to fill in missing data (e.g., for aggregated data items) or the replacement of erroneous data (as determined by quality control procedures). Aggregated/Summarized data statistics Method: a textual description of the aggregation method. Number of observations used: the actual number of observations used in the summary exclusive of imputed or altered data. Observation units: the level from which the aggregation is made (e.g., hours for daily summaries; days for annual summaries). Distribution statistics: standard deviation and selected percentiles (e.g., minimum, 5th, 25th, 50th, 75th, 95th, and maximum) from the data from which the aggregation is made. Precision: where possible, a calculated precision for the aggregated data assuming only sampling bias. Precision method: the methodology used to calculate the precision. Transformed data statistics Method: a textual description of the computational method External data name External data value The data dictionary may also include recommended data records (logical combinations of data elements) as an aid in constructing databases for the ADMS.
Keywords
traffic data; intelligent transportation systems; traffic statistics
The title and scope are in draft form and are under development within this ASTM Committee.
Citing ASTM Standards
[Back to Top]
