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Wei Zhang

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  1. 2 votes

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    Wei Zhang commented  · 

    An intersection involves two intersecting roads. The road that carries higher traffic demand and (usually) with higher speed limit is the major road. An major approach is a leg located on the major road.

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    Wei Zhang commented  · 

    This study calls for identifying vehicles in two types of zones: dilemma zone, and trajectory conflict zone. The dilemma zone is a segment upstream of the intersection (for this study, consider the dilemma zones on major approaches only), from which it takes a vehicle 2.5 sec to 5.5 sec to travel to the intersection stop bar. The dilemma zone is a function of detected vehicle speed. For a vehicle approaching the intersection at 45 mph (66 ft/s), its dilemma zone starts at 363 ft and ends at 165 ft upstream of the intersection; for another vehicle approaching the intersection at 50 mph (73.3 ft/s), its dilemma zone is 403 ft to 183.3 ft upstream of the intersection. For this study, focus the dilemma zone analysis on high speed (over 40 mph) vehicles on the major approaches only during the Yellow phase.
    Although trajectory conflict can happen anywhere, for this study, the focus may be placed in the area within 75 ft of the intersection stop bars (include the pedestrian crossings). Trajectory conflicts may be vehicle-vehicle, vehicle-cyclist, and vehicle-pedestrian. The time-to-collision of detected trajectories may range between 0 to 2 seconds (this is an arbitrary threshold for now).
    The offeror should explain how they intend design and implement algorithms to fulfill the requirements.

  2. 1 vote

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    Wei Zhang commented  · 

    Yes, a proposal for evaluating outputs from speed safety cameras is considered unresponsive.

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    Wei Zhang commented  · 

    The Speed Safety Cameras referenced aim to detect and capture the speeding vehicles. For this topic, detecting vehicles caught in dilemma zone is a prediction of some vehicle(s) may run the red light regardless of whether they are travelling at/below the speed limit or above the speed limit.

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    Wei Zhang commented  · 

    Concur with Robert M.

  3. 1 vote

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    Wei Zhang commented  · 

    Response (02/03/2022)
    Offerors are encouraged to reach out to state/local agencies having multiple intersections on major arterial roads deployed with surveillance and traffic control cameras and develop proposals accordingly. The frame rate and resolution depends on the field installed cameras. Offerors should specify the field of views based on needs of detection.

  4. 2 votes

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    Wei Zhang commented  · 

    The provided definition of dilemma zone (2.5s to 5.5s travel time to intersection stop bar at time of start of Yellow Phase) factored in the variations in travel speed of different vehicles. Since this topic’s intent is to explore feasibility of edge computing to real time traffic control, offerors may base on the range of detected approaching speeds, define a practical physical distance range on each major approach. Note the interest is only in high speed (40 mph or above) vehicles caught in dilemma zone.

  5. 2 votes

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    Wei Zhang commented  · 

    For this topic, offerors may also use 20 percent false-positive rate as a metric of success, they are also welcome to propose more realistic metric of success.

  6. 3 votes

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    Wei Zhang commented  · 

    Suggesting adaptive changes to the signal timing plan so that the number of vehicles caught in dilemma zone would be minimized is a plus. Implementing the adaptive changes to signal timing may require signal controller specific knowledge. For the topic, the minimum requirement is to be able to detect the signal phasing status at time of event logging.

  7. 3 votes

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    Wei Zhang commented  · 

    This topic requires identifying both types of conflicts. Vehicles caught in the dilemma zone are high speed vehicles typically outside of the 75 ft limit of intersection, they only need to be detected during the Yellow Phase of Major approaches. Trajectory conflicts may concentrate in the area within 75 ft of intersections.

  8. 1 vote

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    Wei Zhang commented  · 

    The intersections under control by the edge server can be in one geographic location. Offerors are welcome to propose the option of using one edge server to control intersections located at different geographic locations with different situational aspects, to demonstrate parallel processes may be initiated from the edge server, and each process may be configured with its own location specific parameters, as long as the video/text data from all intersections can be streamed to the edge server within the latency requirement.

  9. 1 vote

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    Wei Zhang commented  · 

    Yes, real time analysis and logging is required. In Phase I, videos and text data can be pre-recorded from real intersections with relevant data. In demonstration of the proof of concept, real time steaming of the video text data (from other computer(s)) to the demonstration edge server is required.

  10. 1 vote

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    Wei Zhang commented  · 

    The edge server is bounded by a (dedicated) single physical box, located say within 0 - 10 miles of the intersections under its control. The offeror may specify a configuration in 5G Internet data communication, so that the differences in latency of data transfer between different intersections and the edge server will be neglectable while the subscription cost is doable under given budget. The intended operating agency should be able to upgrade the edge server (memory, CPU, GPU, application software) based on needs. However, it is acceptable for offerors to offer virtual edge server(s) (if they have demonstrated prior experience) that satisfy the performance requirements.

  11. 2 votes

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    Wei Zhang commented  · 

    Definition of False Positive: If an event is identified and logged by the algorithm, but never really happened, the detection result is considered “false positive”. For potential red light running and trajectory conflict events, the duration of time-to-collision, and visible evasive actions are elements that can be used to judge the True/False of a flagged event. For the scenario described, if the “averted” action is gentle and gradual and of longer duration, it would be a false positive; if the evasive action taken by one or both parties is sudden and severe, it would be considered is a positive detection.

    All recorded time series data (video or text) must be time stamps clearly displayed on all image frames and text rows, the events identified by algorithm(s) must also be tagged with timestamps for ease of verification.

  12. 3 votes

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    Wei Zhang supported this idea  · 

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