ArriveLah - Singapore Bus Arrivals

Natural language bus lookup for Singapore.

Trigger Format

bus from \x3Csource location> to \x3Cdestination location>

Examples:

• "bus from Silat Road Sikh Temple to Queens condo"
• "bus from Tanjong Pagar MRT to VivoCity"
• "bus from my office to home"

Step-by-Step Workflow

Step 1: Geocode source location

Use web_fetch to resolve the source location to coordinates via OneMap API:

https://www.onemap.gov.sg/api/common/elastic/search?searchVal=\x3Csource>&returnGeom=Y&getAddrDetails=Y&pageNum=1

Extract LATITUDE and LONGITUDE from the first result.

Step 2: Find nearest bus stops to source

Fetch the full Singapore bus stop list and find stops closest to source coordinates:

https://busrouter.sg/data/2/bus-stops.json

This returns a JSON object where each key is a bus stop code, with fields: description, road, lat, lng.

Compute distance using: sqrt((lat2-lat1)^2 + (lng2-lng1)^2) (approximate is fine for short distances). Pick the 3 nearest stops within ~300m.

Step 3: Geocode destination location

Same as Step 1 for the destination. Extract its coordinates.

Step 4: Find which buses go from source stops toward destination

For each of the 3 nearest source stops, fetch arrivals:

https://arrivelah2.busrouter.sg/?id=\x3Cstop_code>

Then for each bus service at those stops, check if it passes near the destination using:

https://busrouter.sg/data/2/routes.json

This maps bus service numbers to arrays of stop codes in order. Cross-reference with bus-stops.json to get coordinates of each stop on the route, and check if any stop is within ~400m of the destination coordinates.

Keep only buses that:

1. Have the source stop before the destination stop in their route (correct direction)
2. Pass within ~400m of the destination

Step 5: Fetch live arrival times

For each matching bus at the source stop, get from the arrivelah2 response:

• next.duration_ms → minutes until next bus
• subsequent.duration_ms → minutes until bus after that
• next.load → seat availability: SEA = Seats Available, SDA = Standing Available, LSD = Limited Standing
• next.feature → WAB = Wheelchair accessible
• next.type → DD = Double decker, SD = Single deck, BD = Bendy

Step 6: Format and return

🚌 Buses from [Source Stop Name] → [Destination]

Bus [XX]
  ⏰ Next: X min | Then: Y min
  💺 [Seats Available / Standing / Limited Standing]
  🚌 [Double Decker / Single Deck]

Bus [YY]
  ⏰ Next: X min | Then: Y min
  💺 [Seats Available / Standing / Limited Standing]

📍 Stop: [Stop Description], [Road Name] (Stop code: XXXXX)

If no direct bus found, say so and suggest nearest MRT or alternative.

Load Code Reference

• SEA = Seats Available 🟢
• SDA = Standing Available 🟡
• LSD = Limited Standing 🔴

Bus Type Reference

• DD = Double Decker
• SD = Single Deck
• BD = Bendy Bus
• WAB = Wheelchair Accessible Bus

API Endpoints (no auth needed)

• OneMap geocode: https://www.onemap.gov.sg/api/common/elastic/search
• Bus stops: https://busrouter.sg/data/2/bus-stops.json
• Routes: https://busrouter.sg/data/2/routes.json
• Live arrivals: https://arrivelah2.busrouter.sg/?id=\x3Cstop_code>