Also use construction_date as alternative to start_date

[danrademacher]

From natfoot on OSM slack:

There are somethings that are started but are not start_date_date= yet and are rendering at all times. to at least get it to "disappear" before the construction_date=

A few steps to see about this:

1. Check taginfo to see how prevalent the tag is: https://taginfo.openhistoricalmap.org/keys/construction_date. So 58 items have that tag. Here's a link to those on Overpass
2. See if the field is in the vector tiles. Here's an example way https://www.openhistoricalmap.org/way/198742611, and here in vtiles, https://vtiles.openhistoricalmap.org/#16/47.64018/-122.12904

   The answer is, no, we are not passing this field into vector tiles, so without adding it we can't make the timeslider operate on it.

To make this happen we need to:

• [ ] Add construction_date to vector tiles so we can filter based on that
• [ ] Refactor the timeslider to look for either construction_date or start_date to start drawing a shape.

Questions:

• There are 449,363 objects with start_date. Is there enough use and support of construction_date to refactor the timeslider to operate on it as well?
• Is there some difference in how we should treat those construction vs start dates?

[1ec5]

I wasn’t aware of construction_date, even in OSM. Since OHM has a richer data model, I’ve been mapping a distinct under-construction building coincident with and connected to the finished building. This also allows additional flexibility when some parts of a building are finished before others, the building’s name changes during construction, or construction hasn’t completed yet. The vector tiles technically already support this modeling, but currently the style doesn’t visually distinguish building=construction from other buildings. Besides buildings, other features could benefit from the same treatment using the construction: lifecycle prefix.