Time of day variation is complex for simple changes

[e-lo]

I'd like to flag what I think is a significant drawback of the current data mode for time of day variable. Specifically, I have found it frustrating that:

1. a simple change by time of day requires many entries, and
2. the same table could use a variety of foreign keys which depend on the entry; this makes merge and joins.

I propose that we have the following model to make simple things simple:

link can be overridden by link_tod which can be augmented by link_lanes_tod

• link is treated like the default for the whole day; link_tod has the same attributes as link with the addition of a time of day. This allows simple changes in lanes, tolls or restrictions by time of day to only have one additional table.
  • link_lanes_tod specifies changes to certain lanes by time of day with the assumption that the rest remain as they were. This allows a lane restriction to occur on a single lane without having to specify it for the rest of the lanes (assuming there are no restrictions).

Anything in a link can be overridden by a segment file.

link can be overridden by segment link_tod can be overridden by segment_tod link_lanes_tod can be overridden by_ segment_lanes_tod

Only meso/micro models will need to specify segments (likely) so you wont make simple merges between macro-scale data more complicated by having to do conditional joins depending on segments vs links.

[ianberg-volpe]

We have added TOD.md to the spec-as-code branch, which includes link_tod, link_lane_tod, segment_tod, segment_lane_tod files. We also created a new segment_lane table to mirror segment_lane_tod (for lane add/drops, or changes to characteristics of a lane on a segment).

See the entity-relationship diagram below: