Which states cut axle and gross weight during the spring thaw, what each one publishes, when we last read it, and a direct link to the state's own bulletin. A load that is legal on a road in July can be illegal on the same road in March.
We never tell you a road is clear. Restrictions are posted road by road and lift with a few days' notice, so we publish what each state's own document says, the date we read it, and the link. Where a state publishes only a map or a PDF we say so rather than inventing a limit from it, and where our copy is old we say how old and which way that errs.
12 states whose DOT posts and lifts restrictions on the roads it maintains. Each is polled on its own cadence, derived from that state's published season — a statute where one exists, otherwise its own bulletin history.
NDDOT publishes every restricted segment as GeoJSON with the order number, its effective time and the ton limit. This is the one state where we hold segment-level detail.
Six frost zones, each with a published start and end date. MnDOT announces changes at least three days ahead, which is what makes a several-hour poll comfortably fast enough.
Restrictions apply to routes marked "Seasonal" on the MDOT Truck Operators Map — a 25% axle-weight reduction on rigid pavement and 35% on flexible. Which pavement a given mile is, is a property of the road, not of the state, so we never compute the reduction ourselves.
Washington is one of the 21 states this engine already prices permits for, so a restriction here can change a quote we issue. The feed is a typed JSON API and carries a start and end date per restriction.
Zone-based Class II restrictions of 6 tons single / 10 tons tandem, 24 tons gross. Announced by zone, and the same page also carries the frozen-road law, which moves in the opposite direction.
SDDOT sets and lifts restrictions from accumulated freeze/thaw indices and field observation, and announces each change by press release and on this page.
Published through the statewide travel-information map rather than as a bulletin, so we link to it and watch it for change rather than claiming a parsed limit.
Maine calls these posted roads rather than frost laws. The list covers state and state-aid highways and is republished as roads are added and released.
Break-up restrictions are issued regionally by DOT&PF. The season is later and longer than any lower-48 state, which is why this row has its own window rather than sharing the northern-tier default.
Alaska DOT&PF — Measurement Standards & Commercial Vehicle Compliance
Idaho publishes restrictions through the 511 traveller map. There is no bulletin document to cite, so we watch the page and link to it.
Restrictions are announced through the NDOT truck-permit pages rather than as a numbered bulletin series.
Published on the statewide road-conditions map. Wyoming restricts fewer miles than its neighbours because much of the state system is built on free-draining base.
These are routinely listed as "frost law states", and for most of them that is true of the county roads and false of the state system. Knowing which it is decides who you have to call.
ODOT does not impose spring weight restrictions on the state highway system. Ohio frost laws are posted by county engineers and township trustees on local roads, road by road, with no statewide list. Check the county engineer for the specific local roads on your route.
INDOT does not seasonally restrict the state highway system. Indiana frost laws are posted by county highway departments on county roads.
IDOT does not post spring weight restrictions on state highways. Illinois seasonal limits are set by county and township highway commissioners on local roads.
MoDOT runs no annual spring thaw programme. Missouri restrictions are local and episodic; MoDOT publishes any exceptional embargo on its motor-carrier notices page, which is the page linked here.
NYSDOT does not seasonally restrict the touring routes. New York frost laws are posted by towns and counties on local roads, typically for a few weeks in March and April.
Pennsylvania regulates weak roads through YEAR-ROUND posting and bonding, not through a spring thaw season. A posted-and-bonded road is restricted in July as well as in March, so it is a routing question rather than a seasonal one.
CDOT runs no spring thaw weight programme. Colorado closes and chain-controls mountain routes in winter, which is a traction and closure question, not an axle-weight one.
No spring thaw weight programme. New Jersey does not reach the sustained frost depth the northern tier restricts for.
No spring thaw weight programme on the state system.
A mirror with a timestamp is useful precisely because it says what it is not.
21 US states, each named against its own issuing agency's publication — never an aggregator's summary of one. 12 have a state-system programme, 6 post only at county or township level, and 3 have no programme we can cite.
It never says a road is clear — only what the state's document said when we read it. County and township postings are outside every statewide figure, and specific bridge or culvert postings are outside all of them. US states only: we hold no Canadian provincial seasonal data and publish none.
Nothing, and no account. The same data is a JSON mirror at /api/tools/seasonal-restrictions so a dispatcher's own TMS can poll it, and the page renders in full from the compiled registry with the database unreachable.
Every link is the issuing agency's. A commercial summary of a state bulletin is not a citation — it is somebody else's reading of one — so aggregators were used as a map to find these pages and appear nowhere in the data.
The cadence comes from each source's published posting window, not from one global interval: 3-hourly in season, every 12 hours in the 14-day shoulder either side, weekly out of season.
Structured sources become dated restriction rows. A map, a status page or a PDF becomes "this changed, here is the link", because a row invented from a map tile is a guess wearing a citation. Every row carries both dates: the document's own, and ours.
"Which states have frost laws" has a worse answer than a single list suggests, and the wrong answer is expensive in both directions. Telling a dispatcher to watch a DOT bulletin that does not exist sends them looking in the wrong place; telling them the state has no frost laws sends them onto a posted county road.
A local-only row is data, not a gap. It answers "does my lane have a state frost-law problem?" with a cited no, and points at the county-level reality instead of inventing a state bulletin.
These sources are dormant for most of the year and then move several times a week for six weeks. One fixed interval has to be wrong at one end or the other, so each state's cadence comes from its own posting window — a statute where one exists, otherwise that state's observed bulletin history — and the window is recorded with its basis.
Every state's page prints the cadence it is on today and why, so the schedule is auditable rather than folkloric.
All 21 states in our source registry, sorted into three classes. 12 have a state-system programme: the DOT itself posts and lifts restrictions on the roads it maintains. 6 are local-only: the state system carries no seasonal restriction and the posting is done by counties or townships under their own authority. 3 have no spring-thaw programme we can cite at any level. Every row names that state's own publication and links straight to it.
No, and this page never says it is. What it publishes is what that state's own document said when we last read it, together with the date we read it. A restriction can be posted between two readings, and county and township roads sit outside every statewide figure. The state's own page is the authority; this one is a mirror with a timestamp.
Each source is read on a cadence derived from its own posting window rather than on one global interval: every 3 hours inside that window, every 12 hours in the 14 days either side of it, every 7 days the rest of the year, and never for a state with no programme to poll. Each state's own page prints the cadence it is on today, the date we last read the source, and the date the document itself states.
Because of what the state publishes, not how hard we tried. 4 of these sources are structured enough to yield dated restriction rows, so we parse them. 8 publish a rendered map, a status page or a PDF, and a row cannot be produced from those without guessing — so we do not guess: we read them on the same schedule, report when the document changed, and link it. Each state's page says which of the two it is.