Low-traffic neighbourhood tool v2

This is a new version of ltn.abstreet.org. It doesn't have all features from v1 yet, but it solves many problems with the original. Please try both versions and give feedback.

Developer docs

Installation

You'll need: npm, wasm-pack, and cargo.

cd web, and then:

• npm i to install dependencies
• npm run wasm to rebuild the Rust backend
  • vite doesn't automatically rebuild when you edit things
• npm run dev to run locally
  • Changes to the Svelte/CSS usually auto-reload in your browser
• npm run fmt to auto-format code
• npm run check to see TypeScript errors

The tests directory has some diff-based tests. cd backend; cargo test --release will run them. You'll need to follow the instructions below to ensure you have bristol and strasbourg areas set up.

Faster local development

The tool operates on fixed study areas, generated from clips of OSM data. Custom areas imported by the user are always retrieved from the Overpass API, with the latest OSM data. For speed and for deterministic tests, there are also "built-in" study areas, consisting of pre-clipped osm.pbf files that do not automatically use the latest OSM data. These are manually managed and hosted by Dustin on assets.od2net.org.

If you're developing locally, you can avoid hitting od2net.org by setting up two directories in web/public/: osm and boundaries. If web/public/osm/areas.json exists, then the Svelte app will load from localhost, not od2net.org. You can copy from od2net.org to set this up, choosing what study areas to cache:

AREAS="bristol edinburgh strasbourg ut_dallas"

cd web/public
mkdir boundaries osm

cd osm
wget https://assets.od2net.org/severance_pbfs/areas.json
for x in $AREAS; do
  wget https://assets.od2net.org/severance_pbfs/$x.pbf
done

cd ../boundaries
for x in $AREAS; do
  wget https://assets.od2net.org/boundaries/$x.geojson
done

Architecture

The Rust backend crate gets compiled to WASM, with generally type-unsafe APIs in lib.rs. On the frontend side, wasm.ts wraps these APIs in nicer TS APIs. The Svelte frontend calls APIs in the main thread (though moving to web workers later is a possibility). The "important" state is kept in the backend, while the frontend has more ephemeral UI state. The main state is serialized as GeoJSON and kept in the user's browser local storage. The frontend is effectively a single page app, with the Mode toggling between different pages.