5. PLANNING APPLICATIONS

            The essence of the transportation planning process is the development of a comprehensive blueprint for the development and improvement of mass transit, highway, airport, seaport, railroad, bicycle and pedestrian facilities. Specifically, state and metropolitan planning organizations develop their blueprints by assessing their current conditions, system performance, and potential impacts of development/improvement alternatives. The assessments are based on the predicted future implications of these alternatives with regard to system capacity, travel demand, system condition, safety, economic conditions, population, and land use.

            Therefore, accurate, timely and representative data are crucial to estimating current travel demand (passenger and freight movements combined), forecasting future demand, evaluating and projecting the societal and environmental consequences of various developments and projects, and monitoring the performance of the system(s). Roadway and traffic data are the focus of this Chapter from the perspectives of archiving and using archived ITS-generated data.

5.1 STATE-OF-THE-PRACTICE REVIEW

5.1.1 Archiving and Sharing ITS-Generated Roadway/Traffic Data

            ITS-generated traffic and roadway data that are pertinent to transportation planning applications are: traffic volume, speed, and vehicle classification. Specifically, the data collected from the traffic surveillance component of Freeway Management Systems and Arterial Management Systems. Also, data used for electronic screening in the Commercial Vehicle Information Systems and Networks (CVISN) can supplement traffic surveillance data to better estimate vehicle classification data.

            One hundred and six agencies responded to the Freeway Management Survey in both 1999 and 2000. Almost one in three responding agencies in 1999 did not collect any freeway data while this percentage increased to almost 40% in 2000 (Table 5.1). Data collected from this Freeway Management survey range from traffic volume, to information related to intermodal connections. By far the most commonly collected freeway data are: traffic volume, and information on scheduled work zones (Figure 5.1). The most common technique used to collect traffic data is loop detectors, followed by video imaging detectors. Figure 5.2 depicts the prominence of different techniques used to collect traffic data. It is obvious from this figure that less intrusive technologies are becoming popular in collecting traffic data. Traffic volume and vehicle classification data are the two data elements that are most likely to be archived. Eighty-seven percent of the agencies in 1999 that collected traffic volume data also archive them. And, seventy-six percent of the agencies that collect vehicle classification data also archive them (Table 5.1). The most noteworthy observation is the fewer number of agencies that generate and archive lane occupancy data, declining from 39 agencies in the year 1999 to 6 in year 2000. We speculate that data reporting errors led to the downward trend from 1999 to 2000 in terms of fewer data elements being generated and/or archived.

Table 5.1 Number of Agencies that Generate and/or Archive Traffic Data

1999 and 2000 ITS Deployment Tracking Surveys

            *These questions were not asked in 1999

            **These questions were not asked in 2000

Figure 5.1 Data Generated and Archived from Freeway Management Systems

(Out of 74 Agencies Reported Data Generation and Archiving in 1999

Out of 66 Agencies Reported Data Generation and Archiving in 2000)

            Tables 5.2 and 5.3 show the propensity for data archiving in 1999 and 2000, with a significant downward trend. No agencies collect all seventeen data elements identified on the survey questionnaire. In 1999, one agency collected 14 of out the 17 data elements and it archived every data element collected. Overall, 31 of the 78 agencies in 1999 archived all of the traffic data collected (cells on the diagonal line) while the corresponding numbers are 19 out of 66 agencies in year 2000. Ten agencies in 1999 reportedly collected traffic data but did not archive any (the “0“ column).