Queue Warning Implemented as Part of an Integrated Active Traffic Management System Estimated to Reduce Travel Time up to 5.6 Percent and Reduce Crash Risk up to 28 Percent.

Development and Deployment of a Decision Support System for Integrated Active Traffic Management in the Greater Orlando Metropolitan Area was Assessed Using Traffic Simulation.

Date Posted

Integrated Freeway/Arterial Active Traffic Management

Summary Information

Integrated Corridor Management (ICM) aims to increase corridor throughput, improve travel time reliability, improve incident management, and enable intermodal travel decisions, while Active Traffic Management (ATM) maximizes the effectiveness and efficiency of roadways by increasing throughput and safety using integrated systems with new technology. This study aimed to develop a Decision Support System (DSS) for Integrated Active Traffic Management (IATM) of freeways, arterials and collectors. Numerous data sources were utilized in the Greater Orlando Metropolitan Area, including National Performance Management Research Data Set (NPMRDS), Microwave Vehicle Detection System (MVDS), Automatic Vehicle Identification (AVI) and other commercially available real time vehicle location data. Multiple IATM strategies were tested using a simulation-based approach for I-4 Downtown Orlando and SR-417 East Orlando, including Variable Speed Monitoring (VSL), Queue Warning (QW), Ramp Metering (RM), and possible permutations of these strategies in conjunction with one another. The developed DSS was then assessed to determine if it could reduce traffic congestion and improve travel times and travel time reliability in the Orlando region. The data for many of the roadway in this study were collected in March 2017.


A dynamic traffic assignment (DTA) simulation platform was developed to perform microscopic simulations to test IATM control strategies. The effectiveness of each selected IATM strategy under three different congestion levels on both corridors were evaluated using the simulation model. The benefits of these strategies were analyzed in terms of (i) traffic efficiency, (ii) travel time reliability, and (iii) traffic safety. Travel time and travel time rate (TTR) were used to evaluate traffic efficiency. Standard deviation of TTR was used to evaluate travel time reliability. Real-time crash risk was estimated based on pre-developed models of safety to make sure any strategy to improve traffic efficiency and reliability would not negatively impact traffic safety. Additionally, to test the applicability of these strategies and the integration of freeways/expressways and arterials/ collectors, a deterministic macroscopic modeling tool was developed to predict traffic status. Using the results of extensive simulation analysis for the two critical corridors, a DSS for IATM controls was developed to improve traffic performance, with the consideration of balance between freeways/expressways and arterials/collectors.


  • Queue Warning
    • reduced travel time by 5.6 percent on average (Eastbound)
    • reduced the TTR by up to 8.6 percent in congested traffic states, however, this strategy had an adverse effect in free-flow and transitional traffic states.
    • improved reliability on collectors by up to seven percent and up to eight percent on the entirety of the simulated network.
    • reduced the crash risk by 27.96 percent (Eastbound) and by 20.91 percent (Westbound), primarily during high-risk periods. The impact on collectors was insignificant.
  • Variable Speed Limit
    • reduced travel time on average of 8 percent (Eastbound), and 0.8 percent (Westbound). This corresponded to 163 and 13 saved hours during a two-hour peak period on the Eastbound and Westbound directions, respectively.
    • significantly reduced travel time for areas upstream of bottlenecks, but only had one minute of impact on regions downstream of a bottleneck.  VSL was highly effective for regions with transitional and congested traffic states, but not for regions of free-flow traffic states.
    • reduced the standard deviation of TTR, with a percent change of over 15 percent from base-case Eastbound scenarios, indicating a significant increase in travel time reliability. However, no significant changes were observed for the Westbound direction.
    • reduced the crash risk by 9.04 percent Eastbound and had statistically insignificant results on Westbound. Reduced crash risk on collectors by 1.18 percent. Thus, VSL was most beneficial in reducing crash risk on congested freeway segments.
  • Ramp Metering
    • reduced travel time by 2.5 percent for transitional traffic states and by 13.2 percent for congested traffic states. RM reduced crash risk by up to 22.73 percent, especially in high-risk scenarios.
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