Traffic-Controller

Traffic controller state machine

TODO

• Change schema to match the exact type of intersection
  • Discuss possible ways to expand this schema for other types or use different schemas for different types
• Based on type, choose config parser code
• Add missing config parameters:
  • Non-lock memory operation
  • Lock memory operation
  • Presence mode operation
• TODOs in code

Design Specifications

Specifications follow SC DOT design guidelines.

Intersections

• Exactly two roads per intersection
• Intersection has a unique ID and type
• Intersection type defines its configuration and operation
• Roads in an intersection have unique names
• No pedestrian crossings
• One road is designated as a main road, another a side road

Roads

• Each road has exactly 2 directions (opposing traffic)
• Speed limits: 20-60 mph
• The speed limit remains the same in both directions
• Grades are not accounted for (grade 0)

Lanes

• Two straight lanes for through and right turn movements on main road
• One straight lane on side road
• No separate signal for right turn lanes
• A single left turn lane in each direction operating in permitted mode

Phasing

• Four phases (2,4,6,8)
• Main road phases 2 and 6
• No overlap, concurrent, or split phases

Detection

• Stop line detection:
  • Required for side road approaches
    • Non-lock memory operation
  • Not required for main road approaches
• Setback detection:
  • Not required for main road through movements

Signal timings

• Yellow clearance: 3-6 seconds
• Red clearance: 1.5-3 seconds
• Minimum green time:
  • 8 seconds for side road
  • Green rest
• Maximum green time:
  • TBD

Implementation Notes

• The design defines a pattern for the controller implementation based on the requirements outlined above, while leaving most features unimplemented, with only one or two provided as examples.
• JSON is chosen for the controller configuration due to the following advantages:
  • It supports a schema-based configuration pattern, providing guidance for config creators.
  • It enables validation against the schema using online or other tools without executing it on the controller.
  • It facilitates complex configurations, including conditional requirements, while minimizing data repetition.
  • In the future, once a stable JSON Schema validator written in C/C++ becomes available, the custom validation can be replaced with it.

Environment

1. Build the image:

   docker build -t traffic-ctrl:0.1.0 .

2. Run the container:

   docker run -it --name ctr-traffic-ctrl --mount type=bind,src=/home/builder/github_repos/Traffic-Light,dst=/home/developer/Traffic-Light traffic-ctrl:0.1.0

Testing