Modeled Elements

Roadway elements

Roadway elements in the model include roadway segments and intersections.

Modeling of roadway segments includes:
Modeling of intersections includes:
Roadway types
  • Freeways
  • On/Off ramps
  • Arterials
  • Local streets
Segment characteristics
  • Name
  • Speed limits
  • Lane width
  • Lane restrictions (HOV, truck)
Intersection movements
  • Lane assignment on approaches
  • Destination lanes
  • Yielding movements
  • Right turn on red
Turning bays
  • Length
Traffic detectors
  • Size
  • Location

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:

  • 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:

  • 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
  • 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.