Balancing Safety and Capacity in an Adaptive Traffic Signal Control System
Award last edited on: 10/31/2016

Sponsored Program
Awarding Agency
Total Award Amount
Award Phase
Solicitation Topic Code
Principal Investigator
Ziad Sabra

Company Information

Sabra Wang & Associates Inc (AKA: SWA)

1504 Joh Avenue Suite 160
Baltimore, MD 21227
   (410) 737-6564
Location: Single
Congr. District: 03
County: Baltimore

Phase I

Contract Number: ----------
Start Date: ----    Completed: ----
Phase I year
Phase I Amount
This research is designed to develop a methodology that will identify unsafe traffic conditions such as rear-end, angle and left-turn crashes at individual signalized intersections, and in arterial and grid signalized networks. This research project will have a final product in the form of an algorithms, that would be developed to alleviate such safety risks by adjusting controller timing and operational parameters. The direction outlined in this proposal is to follow a three-step product development process. This first step will be to identfy the relationships between traffic signal timing parameters and safety. The second step will be to convert the relationships identified in the first step to an alogrithm that will execute in an off-line environment. The third step will be to convert the off-line process developed in step two to a real-time algorithm that would execute in a modern NEMA and 2070 type controllers in parallel with the adaptive control algorithm. This last step will be developed in Phase II of this SBIR program.

Phase II

Contract Number: ----------
Start Date: ----    Completed: ----
Phase II year
Phase II Amount
This research focuses on the development of a real-time signal timing methodology and algorithms that balance safety and efficiency. This research consists of two phases: Phase I was completed in December 2009; it examined the relationships between signal timing and surrogate measures of safety, namely the frequency of rear-end, angle and lane-change conflicts. The FHWA Surrogate Safety Assessment Methodology (SSAM) was used to evaluate various simulated scenarios to test the relationships between signal timing parameters such as cycle, offset, split, phase change interval, detector extension time, left-turn phase protection options and left-turn phase sequence and the occurrence of traffic conflicts. The objective of this second phase of the research project is to develop algorithms that can balance the performance of the traffic control system for both efficiency and safety and can work with both NEMA and 2070 traffic control firmware. Phase II will include the development of a multi-objective optimization methodology using the five principle algorithms that comprise the proposed adaptive system for tuning the cycle length, splits, offsets, left-turn phase protection treatment and left-turn phase sequence of a set of intersections. Phase II will define the limits for each parameter-tuning algorithm. The set of multi-algorithms that will be developed under this research will extend the parameter tuning approach that was successfully developed in the FHWA ACSLITE project. The new algorithms will provide signal timing parameter sets that improve both the safety and efficiency of the traffic system. If both objectives are not able to be satisfied, the methodology will attempt to improve efficiency as much as possible until safety is detrimentally affected to a user-specified limit.