The Impact of SJTPO’s Traffic Signal Inventory on Signal Operations

As technology advances, so does the need for data—information that allows engineers, planners, and others to utilize innovative ways to improve transportation and safety. To implement smart traffic systems, whereby centrally controlled traffic signals and sensors regulate the flow of traffic, agencies must know the present state of their traffic signal infrastructure. The South Jersey Transportation Planning Organization (SJTPO), the metropolitan planning organization for four counties in South Jersey, sought to better understand their infrastructure by developing a database of all traffic signals in the region. Completed in 2017, the database provides local agencies with the information needed to target intersections and signals for upgrades and replacements. Replacement with newer integrated traffic signals improves traffic flow, allows for remote signal monitoring and regional signal maintenance, and supports bicycle and pedestrian improvements at intersections.

A traffic signal located in SJTPO’s region. (Source: Tracy, 2017)

In 2016, SJTPO sought to create a database for all traffic signals within Atlantic, Cape May, and Salem Counties. Previously, Cumberland County had developed a traffic signal inventory which SJTPO plans to integrate into the new, comprehensive database. SJTPO and county governments wanted to know the count, age, and types of signals in their jurisdictions. An SJTPO study in Vineland found that many of their signals were very old, with one using circa 1955 electromechanical components to operate. In addition, traffic signal maintenance progressively transferred from municipalities to counties and records of some signals were found to be deficient. The lack of information needed to properly maintain signals was a major impetus for creating the database, according to Andrew Tracy formerly of SJTPO (Source: Tracy, 2017).

Agencies across the country have created similar traffic signal databases. The Chicago Metropolitan Agency for Planning (CMAP), the regional metropolitan planning organization for Chicago and the surrounding seven counties, undertook development of a signal database in 2013 for the region, with the first version released to the public in 2018. CMAP’s goals for the database reflect those of SJTPO. The agency seeks to use the information for planning, and targeting specific signals and intersections for upgrades and replacement.

For an RFP issued to support its regional signal timing initiative,  SJTPO included a list of specific intersections identified by the counties for possible improvements. Extensive outreach to counties and municipalities to acquire signal data and plans took place prior to the database assembly to minimize the field work needed. For all data acquisition requiring field work, the subcontractor created an application to minimize errors with data input. The participating counties gave data collectors the keys to their controller cabinets along with a permission note in case police questioned them during their field work efforts. The signals were classified by features such as signal location, mast arm, head, sign, and presence of pedestrian push buttons. Additional information collected included intersection features such as ADA ramps, crosswalks, etc.

A look at SJTPO’s map and reviewer application for data input. (Source: Tracy, 2017)

Traffic data was also collected at identified intersections, including turning movement counts, queue lengths, delays, and travel times. This information could be used for traffic simulation modeling, performance measurement of intersections, and  revised signal timing plans. Extensive photography of the signals and intersections complemented the data set and provided visual aids. In total, 431 signals, including 258 traditional traffic signals and 173 beacons, were logged in the database across the 3 counties. The signal inventory was completed in 2017 and each county updates the database when a signal or intersection receives upgrades.

The traffic signal inventory database has created a variety of benefits for SJTPO and the region’s residents. One of the most noticeable benefits for local agencies has been access to data to target specific signals for upgraded technology, such as vehicle detection cameras and GPS clocks for signal coordination, or installation of new signals. The database can help identify intersections for bicycle and pedestrian facility improvements and greater accessibility for individuals with disabilities, such as wheelchair ramps and improved crosswalks. Signal upgrades benefit residents by improving traffic flow, and allowing for implementation of remote signal monitoring and signal maintenance at a regional, rather than local, level. Finally, the database reinforces knowledge preservation to ease any transitions in the event of staff turnover.

For other agencies considering a similar database, a Signal Inventory configuration is available via Collector for ArcGIS and performs similar functions as the SJTPO in-house application. Additional information on the process for assembling the SJTPO’s Traffic Signal Inventory Database can be found in a webinar (see below)  hosted by the Mid-Atlantic Geospatial Transportation Users Group.

Sources:

Chicago Metropolitan Agency for Planning. “Highway Traffic Signal Inventory: Draft Proposal.” CMAP, October 29, 2015. https://www.cmap.illinois.gov/documents/10180/481346/RegionnalSignals_Proposal_20151029_forRTOC.pdf/3aef6a03-a792-44ed-9515-11496c9c25f8.

South Jersey Transportation Planning Organization. “Request for Proposals: Regional Signal Timing Initiative.” SJTPO, July 13, 2017. https://www.sjtpo.org/wp-content/uploads/2017/03/SJTPO-RFP-Regional_Signal_Timing_Initiative.pdf.

Tracy, Andrew. October 30, 2017. The South Jersey Regional Traffic Signal Improvement Program. Presentation. https://www.sjtpo.org/wp-content/uploads/2017/11/CAC-10-30-2017-Andrew-Tracy-Signals.pdf.

Tracy, Andrew, Colleen Richwald, David Braig, and Matthew Duffy. October 12, 2017. https://www.youtube.com/watch?v=mMO7-NYuXZ0.

Getting through the Green: Smarter Traffic Management with Adaptive Signal Control

NJDOT Assistant Commissioner for Transportation Systems Management, C. William Kingsland, spoke about Adaptive Signal Control (ASCT) during the third Lunchtime Tech Talk hosted by the Bureau of Research on November 29, 2017.

The Federal Highway Administration (FHWA) defines ASCT as technologies that capture current traffic demand data to adjust traffic signal timing to optimize flow in coordinated traffic signal systems.  FHWA established ASCT as one of its Every Day Counts Round One initiatives in 2011-2012. New Jersey has implemented ASCT through the work of the Traffic Management Systems unit.

Assistant Commissioner Kingsland pointed out that commuters anticipate the time it will take for their typical commute routine and that reliability in travel time is important; people do not like fluctuation in the time it takes to get from A to B. When there is reliability of travel time, people’s expectations are met. ASCT effectively reduces congestion and fuel consumption, thus reducing complaints and frustration.

The ASCT system continuously learns based upon the traffic that is out there and will respond to changes in traffic patterns. Thus, the ability to adapt to unexpected changes in traffic conditions will produce improved mobility through a given area. Furthermore, as connected vehicles become more prominent, the system has the ability to gather information through Vehicle-to-Infrastructure communication and provide timely data of vehicle spacing and signal timing.

Assistant Commissioner Kingsland also provided some highlights about COAST- NJ, the management system developed by AECOM and the New Jersey Institute of Technology that is used to help decide where the ASCT systems will be placed. Using quantitative analysis, the tool ranks sections of corridors based on severity of congestion, variability of congestion, signal spacing, and traffic volume. COAST -NJ provides a classification system scoring process that encompasses 2,562 signalized intersections, 297 signalized arterial corridors, and 56 signal systems. It was officially released for use in March 2017.

During the Q&A portion of the Tech Talk, a member of the audience asked whether the system retains the collected traffic flow information to be able to look back to a certain date and time. The answer is that yes, it can. The issue, however, becomes length of records retention and where to store all of this information over the long-term.

In NJ, some of the NJDOT project locations with ASCT are along Route 130 (MP 69.79 to 74.51) with 15 intersections tied in; Route 168 (MP 6.79 to 9.72) with 11 intersections; and Route 32 (MP 0.0 to 1.20) with two intersections. Mr. Kingsland noted that Route 18 South in New Brunswick to East Brunswick is about to go online

Other agencies are also implementing ASCT. While not a NJDOT project, in the Meadowlands area there are 140 intersections tied into one ASCT system area managed by the Meadowlands Commission.

Mr. Kingsland was asked if rural areas with large distance between signals could possibly have cameras placed at intermediate sections between intersections. Kingsland replied that they certainly could, but the cost of such projects is prohibitive at this point in time.

Due to popular demand, Assistant Commissioner Kingsland presented this Tech Talk again on January 29, 2018.

Resources

Kingsland, W. (2017). Adaptive Signal Control—Getting Through The Green (Presentation).