In our ever more connected world, real-time information is playing an increasingly important role in how transportation agencies monitor and manage the transportation network.
To meet its real-time information needs, the Connecticut Department of Transportation (ConnDOT) recently completed development of its Real-Time System Management Information Program (RTSMIP), a program designed to monitor and report real-time traffic and travel conditions on major highways throughout the state. This real-time traffic information is made available not just within the agency, but also to other public agencies and the general public. “Real-time information plays an important role in our overall strategy for managing roadways and providing services to the traveling public,” reported Hal Decker, principal engineer at the ConnDOT Bureau of Highway Operations.
As part of the federal SAFETEA-LU legislation, all states were required to establish a program to monitor and report real-time traffic and travel conditions on major highways by November 2014. The legislation required states to provide real-time information on four categories of traveler information: construction and lane/roadway closure information, weather information, incident information and real-time travel time information. This legislation also established the provisions and parameters for states to provide travel and traffic condition information in a timely and accurate manner. In 2011, as rulemaking and guidance on this legislation was being developed by the U.S. DOT and provided to the states, ConnDOT began an internal assessment of its existing real-time information data collection and data-sharing capabilities.
Existing ops
Prior to the federal rulemaking, ConnDOT was already meeting several of the federal real-time traffic information requirements. The Bureau of Highway Operations manages two highway operations centers, located in Bridgeport, Conn., and Newington, Conn. System operators at these two centers monitor roadway conditions across the state in real time using existing sensors and camera coverage of state roadways. Operators utilize ConnDOT’s current statewide Advanced Traffic Management System (ATMS), called CRESCENT (Connecticut Roadway Event System for Congestion Evasion and Notification of Traffic), to collect real-time traffic and travel condition information for the state’s entire limited-access highway network. Developed by IBI Group, CRESCENT allows operators to monitor and manage highway events and directly control devices in the field, such as variable message signs (VMS) and highway advisory radio (HAR).
Other ConnDOT bureaus report construction, weather and storm information to the operations centers, and this information is again collected and disseminated via the CRESCENT system. The CRESCENT system uses Geographic Information System (GIS) mapping to geo-locate this information. Rules logic, defined by ConnDOT, automatically generates responses for operators to approve and send information out to various information dissemination platforms. Real-time information on construction, weather, incidents and delays is disseminated to the general public via VMS and HAR in the field, and the department’s traveler information website. Data collected using CRESCENT also is made available internally for departmental use via an FTP site, as well as to other agencies and third-party stakeholders through the CRESCENT XML feed. Based on its existing operations, ConnDOT determined it was already providing three of the four types of real-time information required by the federal legislation: construction information, incident information and weather information. ConnDOT documented its data collection, verification, data entry and data-quality measures for these three types of real-time information.
Implementation
In order to be fully compliant, however, ConnDOT needed to develop a reliable method of collecting and disseminating real-time travel time information for all interstates throughout Connecticut.
In 2013, ConnDOT tasked IBI Group with enhancing the travel time functionality of the existing CRESCENT ATMS software. Given the project schedule, ConnDOT and IBI Group pursued a phased approach to software development and implementation. Phase 1 of the software development effort focused on calculating and configuring route travel-time information and configuration and display of this information on VMS and XML feeds. Phase 1 was not dependent on the selection and procurement of a third-party data provider and was therefore undertaken and completed in 2013. Phase 2 of the travel-time functionality software development was dependent on third-party data being provided and could not commence until ConnDOT had secured access to third-party real-time traffic data. In mid-2014, ConnDOT successfully secured access to a link-level traffic data feed provided by Transcom. Transcom is a coalition of 16 transportation and public safety agencies in the New York/New Jersey/Connecticut metropolitan region. Phase 2, which included the successful integration of the real-time traffic data and implementation of other additional travel time enhancements to CRESCENT, was completed in October 2014, prior to the federal deadline.
Transcome continually updates its data feed, and the CRESCENT software automatically incorporates this feed on a configurable basis (initially set to every five minutes). Once received, the link traffic data provided by Transcom is subjected to five validity checks to ensure data timeliness, data quality and data stability.
Following these validity checks, calculated link travel-time data is aggregated into route travel times. These route travel times are then saved to the CRESCENT database. Then based on rules logic, this route travel-time information is sent to a variety of distribution methods, as appropriate, such as VMS, the ConnDOT website, and the CRESCENT XML feed. The travel-time information also is graphically displayed on the CRESCENT GUI to provide operators with situational awareness. Travel times for all routes, even those without a VMS, are made available to the general public via the department’s website. In October 2014, these travel-time routes initially covered all interstates in Connecticut. In June 2015, ConnDOT expanded coverage to also include several additional routes of significance and state roadways, including the Merritt Parkway.
While the link traffic data provided by the Transcom data feed is assumed to be accurate, the department also conducted an independent evaluation of the travel-time data being provided and found that it exceeded the 85% accuracy requirement stipulated by the federal legislation. ConnDOT has already begun to use these route travel-time comparisons to modify and adjust route calculations and travel-time information. For example, with the collection of the probe vehicle data, ConnDOT was able to determine that the I-91 northbound travel-time routes should be adjusted to provide improved travel times to the general public. Additional travel-time analysis in the future will allow the department to further refine the travel-time information it provides. ConnDOT currently plans to collect independent probe vehicle data on a semi-annual basis going forward to further gauge the accuracy and reasonableness of the Transcom data for specific routes over time.
Lessons learned
Software development: The phased software development approach was instrumental in ensuring that the enhanced travel-time functionality was implemented in time to meet federal deadlines. The project also benefitted from detailed documentation of software needs, and a delineation of software features and functionality. ConnDOT emphasized that the travel-time system needed to be flexible to handle a wide variety of VMS sizes, message formats and display capabilities. The software also needed to make it easy to modify existing travel-time routes and add additional routes in the future. Lastly, the software needed to emphasize data quality. Data validity checks and confidence measures needed to be incorporated in order to ensure that only high-quality data was being passed on to the general public and other public agencies.
A single integrated system: Rather than having several independent stand-alone systems, ConnDOT made the conscious decision to integrate its real-time information into a single integrated system. All the real-time travel and traffic conditions information is collected in a single database that is available for internal departmental use. This information is also made available to other agencies and third-party stakeholders via a single CRESCENT XML feed. Having all this information in a single database will facilitate future research and analysis by the department into traveler information system performance and other measures of effectiveness. Additionally, by building on its existing ATMS software and utilizing existing ITS infrastructure and equipment, ConnDOT was able to implement its real-time information program covering the entire state in a timely and cost-effective manner. The program also was more easily mainstreamed into the department’s existing activities and standard operating procedures. For example, the travel-time messages on VMS throughout the state can be easily overridden to provide higher priority messages, such as incident information or Amber Alert messages.
Public reception: ConnDOT’s real-time information is made available to the general public via several different dissemination methods, including highway VMS, HAR and the department’s traveler information website: www.ct.gov/dot/. The general public has provided very positive feedback on the traveler information, especially on the travel times posted on the ConnDOT website and the VMS. “This real-time travel-time website application is outstanding,” said one website user. “It is very user-friendly and an additional great tool.”
In response to this positive feedback, ConnDOT has continued to expand coverage of the real-time travel time routes, and also is considering additional future enhancements to its real-time travel-time information program. TM&E
