Spring Load Limits API for Trucking Compliance

Every spring, northern states and provinces post weight restrictions on rural roads as frost leaves the ground. Pavement is at its weakest during the thaw, and an unrestricted heavy load can do six-figure damage to a single county road. So every March through May, DOTs publish a moving target of seasonal limits — and every fleet dispatcher has to figure out which roads their loads can still use.

The problem isn’t a lack of data. It’s that every state and province publishes restrictions differently: different file formats, different date conventions, different geographic references (sometimes a shapefile, sometimes a sentence like “CSAH 5 from TH 10 to CSAH 12”). Fleet operators end up checking six DOT websites by hand and copy-pasting into a dispatch sheet.

Road511 normalizes spring load limits from MN, WI, MI, ON, QC, and NS into one API with polyline geometry, active date ranges, and a corridor endpoint that flags every restriction your load would violate along a planned route.

The Data

Every restriction is a feature on the /features endpoint with feature_type=weight_restrictions:

curl "https://api.road511.com/api/v1/features?type=weight_restrictions&jurisdiction=MN" \
  -H "X-API-Key: your_key"

{
  "data": [
    {
      "id": "mn-wr-zone3-seg12",
      "jurisdiction": "MN",
      "feature_type": "weight_restrictions",
      "name": "CSAH 5 - Frost Zone 3",
      "start_time": "2026-03-10T00:00:00Z",
      "end_time": "2026-05-15T00:00:00Z",
      "properties": {
        "restriction_type": "seasonal_weight",
        "weight_limit_tons": 5,
        "frost_zone": "Zone 3",
        "from_location": "TH 10",
        "to_location": "CSAH 12"
      }
    }
  ]
}

Each restriction carries:

• Polyline geometry — the exact road segment, not just a centroid point.
• Start/end dates in start_time / end_time, so you can filter to what’s active today or look at what’s coming next week.
• Weight limit — in tons (MN), as a percentage reduction (MI), or by road class (WI).
• Location description — the human-readable from/to landmarks fleet managers still need on a dispatch sheet.

Coverage

Coverage expands as more jurisdictions publish machine-readable feeds. The schema stays the same — new sources slot in under the same feature_type with the same field set.

Corridor Check

Listing restrictions by jurisdiction is fine for a dashboard, but the question dispatchers actually ask is: “If I send this 30-ton load from Minneapolis to Fargo, what restrictions am I going to hit?” The /truck/corridor endpoint answers that directly:

curl "https://api.road511.com/api/v1/truck/corridor?from_lat=44.98&from_lng=-93.27&to_lat=46.87&to_lng=-96.77&buffer_km=10&weight=30" \
  -H "X-API-Key: your_key"

The server computes a route between the two points, buffers it by your tolerance (buffer_km), and returns every weight restriction along the corridor that your weight would violate. Active-window filtering is built in, so the response only includes restrictions that are in force today.

The same endpoint can be requested as GeoJSON (/truck/corridor/geojson) and dropped onto a Leaflet or Mapbox route preview — restrictions render as polylines you can highlight in red beside the planned route.

Historical Tracking

Road511 captures every restriction’s lifecycle in feature_history: when it was first posted, when the limit changed, and when it was lifted. Over multiple seasons, that history surfaces patterns that aren’t in any single year’s feed:

• When each state typically starts and ends its restriction season.
• Which zones get restricted first — the geographic progression of thaw.
• Year-over-year drift in posting dates as winters get warmer.

Useful if you’re building a seasonal planning tool, doing pavement-impact research, or just want to know whether the late-March window in northern Wisconsin is reliably open this year.

Who Uses This

• Fleet dispatch software — replace manual DOT-website lookups with a single API call before a load is dispatched.
• TMS and routing platforms — layer weight restrictions onto truck-legal routing so the engine never proposes a corridor it can’t legally use.
• Permit and compliance tools — flag scheduled loads whose weight exceeds an active restriction on any segment in their route.
• Pavement and infrastructure research — longitudinal history of restriction timing for thaw-cycle and pavement-life studies.

Try It

• API docs — full parameter reference for features, truck/corridor, and the GeoJSON variants.
• Free API key — 14-day trial, no credit card.
• Live map — weight restrictions render as polylines alongside cameras, work zones, and DMS signs.