A consumer nav app tells the driver where to turn. It will not tell the dispatcher where the 11-hour driving clock runs out — and, more importantly, whether there is legal parking when it does. That second question is the one that strands a truck at 11 PM on the shoulder of an off-ramp with every nearby lot already full.
Road511’s routing endpoint now answers it. Send the driver’s Hours-of-Service clock along with the route, and the response carries an hos[] array: every point on the corridor where the driver must take a break or stop driving under the selected regime, the projected time they reach it, the legal deadline, and — the part that matters operationally — the truck parking and rest areas actually reachable before that deadline.
How It Works
It rides the same call as everything else routing does: POST /api/v1/routing/route. You already send an origin, a destination, and a truck profile. To get the HOS projection, add an hos block inside the truck object describing the driver’s clock at departure.
curl -X POST "https://api.road511.com/api/v1/routing/route" \
-H "X-API-Key: your_key" \
-H "Content-Type: application/json" \
-d '{
"origin": { "lat": 41.8781, "lng": -87.6298 },
"destination": { "lat": 39.7392, "lng": -104.9903 },
"departure_time": "2026-06-08T06:00:00Z",
"truck": {
"profile": "tractor",
"weight_t": 36.0,
"height_m": 4.2,
"axles": 5,
"hos": {
"ruleset": "us",
"drive_remaining_s": 39600,
"duty_remaining_s": 50400,
"since_break_s": 0
}
},
"enrichment": {
"include_features": ["truck_parking", "rest_areas"]
}
}'
That’s a Chicago→Denver run for a fresh driver on US rules: 11 hours of driving left (39600 s), a 14-hour duty window (50400 s), and zero driving time since the last break. Every counter is “seconds remaining” against the named ruleset’s limit.
The HOS Clock
The hos object is the driver’s state, not a fixed policy. Store only the ruleset on a reusable truck profile — the per-trip counters are supplied inline on each request and merge on top.
Field
Meaning
ruleset
The regime: us, canada_south, or eu. Empty defaults from the deployment region.
drive_remaining_s
Driving-limit budget left.
duty_remaining_s
On-duty window budget left.
since_break_s
Driving time accrued since the last qualifying break.
elapsed_remaining_s
Canada’s elapsed (wall-clock) window budget.
cycle_remaining_s
Weekly / cycle budget (60/70-hour US, 70/120-hour Canada, 56h/90h EU).
Any counter you leave out is read as “a fresh driver” — the ruleset’s full limit. The counters are pointers under the hood, so an explicit 0 (“out of hours right now”) is distinct from “not supplied.”
The Response
The HOS projection is attached to the primary route as an hos[] array, alongside the warnings[] and features[] you may already be using.
{
"routes": [
{
"summary": { "distance_m": 1480200, "duration_s": 54600 },
"geometry": { "type": "LineString", "coordinates": [ /* ... */ ] },
"hos": [
{
"reason": "break_required",
"distance_along_route_m": 642000,
"projected_time": "2026-06-08T14:00:00Z",
"legal_deadline": "2026-06-08T14:00:00Z",
"feasible": true,
"suggested_stops": [
{ "type": "rest_areas", "distance_along_route_m": 631500,
"properties": { "name": "I-80 Walcott Rest Area", "spaces": 22 } },
{ "type": "truck_parking", "distance_along_route_m": 612000,
"properties": { "name": "Pilot Travel Center #412", "spaces": 140 } }
]
},
{
"reason": "drive_limit",
"distance_along_route_m": 905800,
"projected_time": "2026-06-08T17:30:00Z",
"legal_deadline": "2026-06-08T17:30:00Z",
"feasible": false,
"suggested_stops": []
}
]
}
],
"route_id": "rt_5d91c7e2"
}
Each stop carries a reason — the limit that trips there — the distance_along_route_m where it lands, the projected_time the driver reaches it, and the legal_deadline the rule allows. The four reasons:
Reason
What tripped
break_required
The driver hit the drive-time-since-break limit and owes a rest break.
drive_limit
The daily driving limit is exhausted — the driver must stop for the day.
duty_window
The on-duty window closed (or, in Canada, the elapsed window) before the driving limit did.
cycle_limit
The weekly/cycle budget ran out.
The Part That Matters: Reachable Parking
Projecting where the clock runs out is the easy half. The operationally useful half is whether the driver can actually stop there. Each hos stop attaches a suggested_stops[] list — the truck parking, truck rest areas, and rest areas reachable before the legal deadline, ordered closest-to-the-deadline first so the driver squeezes the most legal driving out of the day. That list is drawn from Road511’s own live 511 parking data, the same normalized feeds behind the rest of the API.
And the flag that no consumer navigation app surfaces: feasible. When it’s true, at least one legal stop is reachable in time. When it’s false — as on the second stop above — no legal parking is reachable before the deadline. That is a real compliance risk you want to see at dispatch time, not at the roadside. (feasible is omitted entirely if the parking lookup didn’t run, so a missing flag never reads as a misleading “false.”)
The Regimes
Three Hours-of-Service regimes ship today, each implemented against its actual regulation:
Ruleset
Regulation
Key limits
us
49 CFR 395 (FMCSA, property-carrying)
11h driving, 14h duty window, 30-min break after 8h driving, 10h daily rest
canada_south
SOR/2005-313 (south of 60°N)
13h driving, bounded by both a 14h duty window and a 16h elapsed window, 10h daily rest
eu
Regulation (EC) No 561/2006
9h driving, 45-min break after 4.5h driving, 11h daily rest
The weekly/cycle caps (US 60/70-hour, Canada 70/120-hour, EU 56h/90h) are modeled when you supply cycle_remaining_s; left unset, the projection focuses on the daily limits. Canadian canada_north and the European aetr regime are planned. If you don’t set a ruleset, the routing handler defaults it from the deployment region — but Canadian operators should always set canada_south explicitly.
Where It Fits
The HOS projection is computed on the route geometry that’s already in hand — it’s pure projection over the polyline, not a second round of routing. It runs for the primary route only, and it rides the routing call you’re already making: no separate endpoint, no separate charge beyond the routing request itself. Routing is a paid-plan feature (featured on Pro+) with a free 14-day trial, so you can wire HOS into a dispatch flow and try it end-to-end before committing.
Pair it with the corridor warnings[] (bridge clearances, weight restrictions, rail crossings, work zones) and the same request answers three questions at once: can this truck legally run this corridor, where will the driver have to stop, and is there parking when they do.
Try It
- API docs — full request and response reference for
POST /api/v1/routing/route
- Truck routing with live hazard warnings — the corridor enrichment this builds on
- Free API key — no credit card, 14-day trial
Plan the route, the legal stop, and the parking — in one call
Send the driver’s HOS clock with the route and get back every required break, every drive-limit stop, and the parking reachable before each deadline. Free 14-day trial. No credit card.