A significant part of the AMS Phase 1 effort focused on collecting, organizing, and analyzing corridor data and converting it into a useful form for modeling and simulation.
When AMS work began, there was no single place where all corridor information was assembled: data was fragmented into multiple databases, across jurisdictions and facilities, stored in different formats, and organized separately. One success of Phase 1 is the extensive amount of data collected about the I-210 corridor. Synthesis of these data provided a comprehensive characterization of the corridor—a broad, detailed, and holistic picture of the corridor's characteristics, operational challenges, capabilities, and user needs. This assessment provided the context for subsequent steps in the AMS process and was instrumental in shaping such decisions as the extent of the freeway to be modeled and in identifying key data gaps for additional traffic studies.
Freeway data quality
As part of the data-gathering effort, the AMS team conducted an in-depth assessment of data quality from loop detectors on the I-210 freeway to identify and prioritize key areas of sensing improvements. These improvements are crucial for real-time situational awareness and model calibration. Inadequate, incomplete, or contradictory data increases risk to the pilot deployment, and may lead operators to make inaccurate assessments about corridor operational needs. Data is the lifeblood of traffic analysis and management, and the importance of high-quality data—including its timeliness, accuracy, and coverage—cannot be overstated.
Although freeway data along the I-210 is generally good, the I-210 Pilot will rely on the continued efforts of Caltrans to maintain existing sensor infrastructure and to improve known issues, such as:
- Ramps for which no VDS is listed in PeMS
- Stations which appear in PeMS to be in a constant failure mode
- Stations that are working but do not capture an entire cross section of flow
- PeMS configuration errors
- Configuration uncertainty, where the exact location of sensors is not clear from PeMS
- Stations that are suspected of having counting errors
Arterial data
A large-scale Synchro model of the I-210 corridor was assembled that includes all intersection signal plans active at 5:00 pm, as well as approach flows and turning volumes from all area traffic studies between 2006 and 2014. There are over 500 intersections coded into the Synchro model, including about 450 signalized intersections, 63 stop-controlled intersections, and 110 intersections with observed traffic counts. Stakeholders have requested the Synchro model and the data used to populate it in order to enhance their operational capabilities. This Synchro model is the repository for “static” arterial data in a single, electronic format. In addition, the team has software tools to extract this data and provide it to the macroscopic model.
For complete details about data gathering and assessment for AMS Phase 1, see the AMS Phase 1 Report.