---
title: "Current chain-control requirements on California mountain highways."
method: GET
path: "/v1/tools/get_chain_controls"
---

# Current chain-control requirements on California mountain highways.

`GET /v1/tools/get_chain_controls`

## Request

- Base URL: `https://mcp.commutescout.com`
- URL: `https://mcp.commutescout.com/v1/tools/get_chain_controls`
- Auth: one of:
  - none
  - API key in header `X-API-Key`
  - HTTP bearer

Current chain-control requirements on California mountain highways.

    Data: Caltrans chain-control status for fixed checkpoints on mountain
    routes (I-80 Donner, US-50 Echo Summit, SR-88, SR-89, and others).
    Levels: R-1 = chains OR snow tires required; R-2 = chains required
    except 4WD/AWD with snow tires on all four; R-3 = chains on ALL vehicles
    (rare, usually precedes closure). Refresh: 5-minute cache.

    Filters: route (e.g. "80", "US-50", "SR-88"); center "lat,lon" with
    radius_km for all checkpoints around a place (e.g. around Truckee),
    whatever highway they are on.

    Off-season (roughly May-October) there are usually no controls anywhere;
    the response says so explicitly rather than returning an empty list.
    Chain requirements can change hour to hour in storms - tell the user the
    data_as_of time and to carry chains anyway when snow is possible.

## Query parameters

- `route` string
- `center` string
- `radius_km` number

## Response `200`

The tool's result.

- object

## Other responses

- `400`: A parameter is missing, unknown or malformed.
- `401`: The API key is unknown or revoked.
- `429`: Slow down; Retry-After says how long.

---

[API](https://skmtc.dev/commutescout/apis/commutescout-api.md) · [All operations](https://skmtc.dev/commutescout/apis/commutescout-api/llms.txt) · [OpenAPI document](https://skmtc.dev/commutescout/apis/commutescout-api/revisions/70427a609edf?raw)