Active Transportation and Demand Management (ATDM) Analytical Methods for Urban Streets

CHAPTER 3. EXISTING DATA SOURCES

As discussed in the Introduction chapter, Task 3 of the project required establishment of a peer review group to provide input on development of the methodologies. The peer review group provided input on which urban street active transportation and demand management (ATDM) strategies should be implemented in the Highway Capacity Manual (HCM), how best to conduct the original research, and how to meet overall project objectives. The final list of peer group members was submitted to the Federal Highway Administration (FHWA) in January 2016. Due to the special nature of Task 3, a dedicated chapter is not needed for the peer review group. However, the peer group's influence on other tasks will be noted when applicable. For example, members of the peer review group were helpful in assembling the data sources for urban street ATDM. The available data sources were the focus of Task 4, as described in this chapter.

Task 4 of the project required identification of available data sources, typically in the form of before-and-after-ATDM-implementation field studies around the country, which might help to develop models for predicting ATDM strategy impacts. However, existing data sources could also include testbeds of research data, simulation platforms, or existing simulation results, which could further provide a basis for ATDM model development. Ultimately, existing data were only obtained for the same three ATDM strategies chosen to be the top priorities of this project, namely: adaptive signal control, reversible center lanes, and dynamic lane grouping. Moreover, only adaptive signal control had a sufficient quantity of existing data studies to support model development. Results of this data review were documented in a detailed technical memorandum in January 2016, and are repeated here in this chapter.

AVAILABLE TESTBEDS

Due to a lack of widespread ATDM implementation on arterial roads, simulation studies would be needed to supplement the field data studies. Existing simulation datasets and testbeds were identified and considered to the greatest extent possible. For example, the Analysis Modeling and Simulation (AMS) testbeds¹ have been identified as good candidates for evaluating ATDM applications and strategies. In addition the Saxton Traffic Operations Laboratory, located at the Turner-Fairbank Highway Research Center, contains a certain number of simulation datasets and resources. Datasets generated by a prior Saxton Lab study on dynamic lane grouping were collected and reviewed for this project.

ADAPTIVE SIGNAL CONTROL (FIELD STUDIES AND SIMULATION STUDIES)

Evaluation of the Virginia Department of Transportation (VDOT) Adaptive Signal Control Technology Pilot Project

• Conclusions are based on testing of the InSync system (Fontaine, Ma, & Hu, 2015).
• Adaptive signal control technology (ASCT) generally improves mainline operations if the corridor (1) is not over capacity (2) does not have traffic or geometric characteristics that impair progressive flow, or (3) does not already operate at a good level of service.
• Side street delays generally increase when ASCT is deployed, although there is usually a net reduction in overall corridor delay.

Cornell Road InSync Evaluation

• InSync improved corridor travel times, but overall average delays increased at the intersections (Hathaway, Urbanik, & Tsoi, 2012).

Adaptive Signal Testing for Recurring and Non-Recurring Conditions

• InSync outperformed other signal timing plans on the intersection, corridor and network- wide levels (Stevanovic, Zlatkovic, & Dakic, 2015).
• The advantages of adaptive traffic control systems were more significant for non-recurring traffic conditions.

SCATS Evaluations

• Overall minor positive effect (Hathaway, Tsoi, & Urbanik, 2012) (Hathaway, Tsoi, & Urbanik, 2012) (Hathaway & Urbanik, 2012).
• SCATS benefitted high-volume intersections.
• Low-volume intersections performed worse under SCATS.
• Positive effect on travel times.
• Minor improvement in intersection-wide delays.
• SCATS appears best for high-volume corridors that prioritize through traffic, and low- volume movements can tolerate larger delays.

Palm Beach TMC Active Arterial Traffic Management Program

• Signal timing control for incident management (Palm Beach County, 2015).

REVERSIBLE CENTER LANES (BEFORE-AND-AFTER FIELD STUDY)

• Significant operational benefits found in Salt Lake City "Flex Lanes" (Avenue Consultants, 2013).

DYNAMIC LANE GROUPING (BEFORE-AND-AFTER SIMULATION STUDY)

• This testbed consists of two signalized corridors in Northern Virginia (Su, Jiang, Jagannathan, & Hale, 2015).
• Most simulation experiments in this study involved two intersections flagged as good candidates for dynamic lane grouping (DLG) treatment. Significant benefits were measured at these two intersections, in terms of average vehicle delay. However, the study identified a total of five intersections that were potentially good candidates for DLG treatment.

CONCLUSIONS AND NEXT STEPS

As shown in this chapter, existing data were only obtained for the same three ATDM strategies chosen to be the top priorities of this project, namely: adaptive signal control, reversible center lanes, and dynamic lane grouping. Moreover, only adaptive signal control had a sufficient quantity of existing data studies to support model development. As such, HCM-compatible models for reversible and/or dynamic lanes would be heavily dependent on simulation studies, to be conducted during Task 6 – Original Research. And although the quantity of adaptive signal data was sufficient to support model development, additional data was still desired for better confidence. The model development effort is described in the upcoming chapters on Task 6 – Original Research. However the next step in the project (Task 5 – Performance Measures) was a review of appropriate system performance measures, which could be effective in assessing ATDM strategy impacts.