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Hazmat and Restricted Cargo Routing

A routing API will return a route for a hazmat load whether or not you told it the load is hazmat. The response will be well-formed. It will contain a polyline. It may also route a tanker of flammable liquid through a tunnel where that is prohibited, past a school, or onto a bridge with a placarded-vehicle restriction. HERE will not warn you, because you did not tell it what you were carrying.

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The problem

Hazardous materials routing is governed by regulation, not preference. In the United States, placarded vehicles are subject to federal and state routing designations. In Europe, ADR classes determine tunnel access. Local restrictions layer on top. The consequences of a wrong route are not customer dissatisfaction. They are:

• Federal and state penalties
• Loss of hazmat endorsement
• Criminal liability in the event of an incident
• Insurance exclusion

This is one of a small number of use cases where a software defect is a regulatory event.

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Who this is for

Chemical and industrial logistics. Fuel and propane distribution. Waste and hazardous waste haulers. Explosives and munitions transport. Any TMS or ELD platform serving carriers with hazmat endorsements.

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Recommended architecture

The system must be able to refuse. A routing request for a hazmat load without a class is not a request to route with defaults. It is an invalid request.

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Relevant HERE APIs, and why

Truck Routing — the only relevant API. Why: HERE’s Routing v8 exposes shippedHazardousGoods as a parameter with class values, alongside tunnel category and the physical vehicle constraints. Physical constraints still apply. Height in centimetres, grossWeight in kilograms, axleCount including trailers. A hazmat tanker is also a tall, heavy vehicle. Both constraint sets are required. category=lightTruck is a legal exemption, not a physical one. It exempts a vehicle from many restrictions written for normal trucks. Physical dimension and cargo restrictions still apply. It does not exempt a hazmat load from hazmat restrictions. weightLimit is deprecated in the current v8 specification in favour of grossWeight. If you are reading an older tutorial, you are reading a deprecated parameter.

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Implementation flow

1. Classify the material in your own system, against the regulatory scheme that applies in your jurisdiction.
2. Map your classification to HERE’s enum deliberately, with a documented mapping table reviewed by someone who understands the regulation.
3. Validate before routing. A load flagged hazmat with no class must fail loudly. Never default.
4. Route with the full constraint set — hazmat class, tunnel category, and physical dimensions.
5. Assert a route was returned. HERE returns 200 with an empty routes array and a notice when no path exists. For hazmat, “no legal route” is a real and correct outcome.
6. Record the constraint set, the route, the timestamp, and the map release version.
7. Verify the driver’s endorsement matches the load. This is not a routing API’s job, and it is your job.

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Production considerations

Constraints belong to the load, not the carrier. The same tractor hauls dry van on Monday and hazmat class D on Tuesday. shippedHazardousGoods is a property of what is in the trailer, and it changes per shipment. Vehicle dimensions belong to the vehicle record. Height, weight, and axle count are not request-time literals. Never hardcode either at a call site. A developer adding a new endpoint who copies a routing call without the constraint set has introduced a defect invisible to code review. Record the map release version. Restrictions change. A route computed in March against a March map may differ from the same route in September. If an incident occurs, you will be asked what the system knew and when. Regulatory data is not uniform globally. Coverage and depth of hazmat restriction data vary by market. Do not assume the same fidelity in every country you operate. Verify against known restrictions in your operating area. Build a test suite of routes that must be refused or diverted, and run it in CI.

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Cost considerations

Hazmat routing bills as a routing transaction. It is not more expensive than truck routing. This is not a cost-optimization page. The economics are irrelevant next to the regulatory exposure. Cache route geometry between fixed points if you like. Do not cache across different hazmat classes, do not reuse a route computed for a different load, and do not let a caching layer serve a class-A route to a class-D shipment because the origin and destination matched. For matrices of hazmat-constrained travel times, Matrix Routing accepts truck mode and vehicle parameters.

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Common mistakes

Setting transportMode=truck and omitting shippedHazardousGoods. The engine is selected. The cargo is not declared. Mapping an internal is_hazmat boolean onto a classed enum. Read the class definitions. Using the deprecated weightLimit instead of grossWeight. Omitting tunnel category. A separate parameter, and the one that governs tunnel access in Europe. Assuming lightTruck waives hazmat restrictions. It waives certain legal truck restrictions. It does not make a flammable liquid non-flammable. Treating an empty routes array as an error to retry. It may be the correct answer. Falling back to car routing when truck routing returns no path. This is how illegal routes reach drivers. Caching on origin-destination without the constraint set. Constraints attached to the carrier rather than the load. Not recording the map release version on a route a regulator may examine. Not verifying driver endorsement. Not the API’s job. Still your problem.

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Production checklist

• Material classification mapped to HERE’s shippedHazardousGoods enum, with a documented mapping table
• Mapping table reviewed by someone qualified in the applicable regulation
• Routing request validated: hazmat load without a class fails loudly, never defaults
• Tunnel category supplied where applicable
• Physical vehicle constraints supplied alongside hazmat class
• grossWeight used, not the deprecated weightLimit
• Empty routes array handled as a legitimate outcome, not retried with relaxed constraints
• No fallback to car routing under any circumstance
• Cache keys include the full constraint set
• Constraint set stored on the load; vehicle dimensions on the vehicle
• Route, constraints, timestamp, and map release version persisted
• CI assertions against known-prohibited segments in your operating region
• Driver endorsement verified against load class before dispatch

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Alternatives and trade-offs

Google Maps Platform offers no hazmat routing capability. This is not a close comparison. If you route placarded vehicles, it is not a candidate. Mapbox does not express hazmat constraints. Same conclusion. TomTom supports ADR HazMat classes with a narrower constraint set than HERE and lower waypoint limits. Competitive in European automotive contexts. Verify current capability and pricing independently. Self-hosted OSRM does not model hazmat restrictions. You would be curating restriction data yourself, for a domain where being wrong is a regulatory event. This is not a reasonable build. Manual route approval. For low-volume, high-consequence hauls — explosives, radioactive materials, oversized chemical loads — a compliance officer reviewing every route is not a failure of automation. It is the correct control. Automate the routing; keep the human in the approval path. A specialist hazmat routing vendor exists in some markets, with jurisdiction-specific designated-route data that exceeds any general mapping platform. If hazmat is your entire business, evaluate them. HERE gives you strong coverage as part of a general routing platform; a specialist gives you depth in one regulatory regime. Refuse to route. The most underrated option. If your system cannot confidently express a load’s constraints, it should decline rather than guess. A dispatcher calling a compliance officer is a better outcome than a driver following an illegal route.

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Related guides

Also: Routing · Matrix Routing · Cold Chain and Restricted Cargo

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HERE documentation

• Routing API v8 reference — shippedHazardousGoods, tunnel category, truck parameters
• Transport modes

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Placematic

• Truck Routing

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