Roadway elements
Roadway elements in the model include roadway segments and intersections.
Modeling of roadway segments includes: |
Modeling of intersections includes: |
Roadway types
Segment characteristics
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Intersection movements
Turning bays
Traffic detectors
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Traffic signals
For traffic signal control elements, the model includes basic timing parameters (cycle length, offset, phase sequence, phase durations) and advanced features such as vehicle-actuated control. But the model must also account for other issues, including:
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Fixed-time control is no longer the default control mode. For example, 95+% of intersections in the I-210 corridor are actuated-coordinated, and some intersections use real-time control.
- Different control programs are used by different agencies, creating a need to develop a uniform modeling framework.
- Several types of detector configurations are used within the corridor both across and within agencies:
More details on the modeling considerations for traffic signals can be found in the AMS Phase 2 presentation.
Ramp metering
Ramp metering elements in the model include the type of metering control (fixed, time-of-day, variable based on mainline vehicle detections) and basic control parameters (min/max flow rate, number of vehicles per green, associated detectors). In addition, modeling must account for:
- ramp metering schedules
- variations in metering operations across ramps
- non-basic ramp metering operations such as queue overrides, mainline congestion override, and dynamic metering algorithms
The following illustration shows a typical detector configuration:
Transit services
For transit services, the model must be able to simulate:
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impacts on vehicular traffic (e.g., bus stopping on the road; transit signal priority/preemption)
- impacts of incidents on bus operation (e.g., delays due to congestion)
- responses to incidents with a transit component (e.g., changes in transit service
The model currently includes the Metro Gold Line (light-rail) and all express and local bus routes:
Modeled elements include:
- location of bus stops
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types of stop (in the roadway or in bus bays)
- service timetables
- dwell times
Additional detail, plus modeling considerations for signal priority/preemption, can be found in the AMS Phase 2 presentation.