Indivisible cargo: legal framework and operations for shippers

A load is indivisible when splitting it costs more than moving the whole. That boundary defines everything: type of authorisation, equipment, escort, lead times and budget. Legal framework and operations for shippers starting out in heavy transport.

An indivisible cargo is goods that cannot be split into two or more parts for transport without unnecessary cost or risk of damage. That is the literal regulatory definition — reflected in article 14.2 of the Reglamento General de Vehículos (RD 2822/1998), developed operationally in Anexo III del Reglamento General de Circulación (RD 1428/2003) and adopted in identical wording by the Servei Català de Trànsit. Indivisibility depends on a single variable: whether the piece can or cannot be split without functional damage or disproportionate reassembly cost. Nothing else.

What gets confused in practice is the difference between indivisible cargo and special transport. A load can be indivisible and still fit within the ordinary circulation regime — a 35 t transformer in a compact body, perfectly indivisible, moves without a Complementary Circulation Authorisation. Special transport arises when the combined vehicle and load in transport position (tractor + platform + cargo) exceeds the mass or dimension limits in Annex IX of the RGV: 40 t as a general rule, 44 t for articulated combinations of 5 axles or more under Orden PJC/780/2025, 2.55 m width, 4.00 m height, 16.50 m length for articulated vehicles, 18.75 m for road trains. Indivisibility and limit excess are independent tests: cargo can be indivisible without requiring an ACC, and there can be ACC operations that do not strictly transport indivisible cargo (assimilated loads).

For a shipper preparing a first heavy operation — a transformer bought from a German manufacturer, a boiler made in Catalonia bound for Aragón, a wind turbine nacelle arriving by sea at Port BCN — understanding both tests separately defines the full legal framework of the operation: type of authorisation (if any), equipment required, administrative lead times, applicable escort and, ultimately, budget.

What the regulation says: the technical definition

The regulatory criterion for indivisible cargo reduces to a single test: the piece cannot be split without functional damage, operational loss or substantial reassembly cost. To certify indivisibility before the authority, the shipper or carrier can provide manufacturer drawings, a technical sheet justifying the functional unity of the piece, or a certificate of impossibility of disassembly where the case requires it.

Once indivisibility is established, the second test — independent — is whether the combination needed to move that piece exceeds the limits in Annex IX of the RGV. If it exceeds them, the operation enters the special-transport regime and requires a Complementary Circulation Authorisation (ACC). If it does not, the cargo is indivisible but the operation runs under the ordinary regime.

A load is indivisible when splitting it costs more than moving the whole. That is the boundary between ordinary transport and special transport.

Three concepts not to confuse

The regulation distinguishes three close figures with different legal consequences. Confusing them is among the most frequent mistakes by non-specialised shippers.

Indivisible cargo

The complete technical unit that moves as a single piece. Typical examples: a 90-250 t power transformer, a 60-90 m precast bridge section, a 50-120 t wind turbine nacelle, an industrial generator rotor, a large hydraulic press, a boiler or chemical reactor assembled in the workshop.

Each unit is transported on its own. One authorisation per piece, one convoy per piece, one operation per piece.

Cargo assimilated to indivisible

A set of elements individually divisible and of the same nature, grouped by destination and shared geometry. The regulation assimilates them to indivisible cargo when the grouping — not the individual pieces — exceeds ordinary limits. Examples: a series of wind blades from the same farm, a batch of precast beams of the same section, a transport of timber poles of uniform length, a shipment of metal profiles of great length.

Assimilation is granted case by case. For cargo assimilated by length (poles, beams, logs), the maximum authorisable mass stays at 44 t — the Annex IX RGV ceiling for combinations with 5 or more axles — and the total combination length must exceed 18 m.

Exception to indivisible cargo

Goods that can be split but are transported grouped in one combination whose total mass does not exceed 100 t. It is a lighter administrative figure than indivisible cargo proper. The DGT contemplates two sub-types:

• Set of singular elements — elements of the same nature and same end use, of identical or differing dimensions, whose grouping exceeds one dimension or mass set by the RGV. A series of wind blades from the same farm, a batch of precast beams of the same section, a shipment of long metal profiles fall into this sub-type.
• Cargo with removable elements — machinery or objects whose intimately joined pieces are separated for transport and reassembled at destination. A mobile crane disassembled into boom, counterweights and chassis, transported in a single combination, is the typical case.

The practical difference from indivisible cargo: the exception allows divisible elements to be consolidated in a single combination under a lighter administrative regime, while indivisibility proper activates the full regime with the documentation and lead times that implies.

How indivisible cargo is transported on trucks: from regime to equipment

Once the cargo is classified, everything else follows from that classification. Indivisibility is not an isolated technical fact: it is the variable that triggers every subsequent operational decision.

Type of authorisation: DGT categories and the Catalan regime

The mass, dimensions and geometry of the combination in transport position (tractor + platform + cargo) determine the applicable authorisation. The DGT classifies ACCs in three categories, with thresholds set on the combination:

An indivisible cargo of 60 t and 25 m long falls into specific. One of 180 t or with significant overhang, into exceptional. The category is not chosen by the shipper: the parameters of the combination determine it.

The Servei Català de Trànsit maintains its own classification for Catalan special authorisations, with operational thresholds different from the DGT categories. Following the SCT instruction of May 2024, the Catalan regime articulates obligations under width and length parameters that may not match the DGT thresholds point by point. That is why, in operations touching Catalonia, the applicable categorisation is set under the SCT regime for the Catalan stretches and under the DGT regime for the rest.

Equipment: the trailer matched to the cargo

Each indivisible-cargo profile requires different equipment:

• Loads with critical height (transformers, boilers) → low bed with gooseneck, platform height 0.30-0.40 m.
• Long loads (blades, beams, precast sections) → extendable platform, usable length adjustable up to 21-24 m.
• Loads extreme in mass or geometry (high-power transformers, bridge sections) → hydraulic modular (SPMT), capable of redistributing axle mass and executing lateral manoeuvres.

The choice of trailer is not independent of indivisibility: the piece dictates the equipment, and the equipment dictates the clearances of the combination, which in turn dictate the authorisation category.

Endorsed study and self-escort regime

The combination dimensions just fixed determine two distinct documents. Non-specialised shippers confuse them and pay for the error with longer lead times: the DGT keeps separate when a study signed by a chartered engineer is required and when all stretches of the itinerary are authorised for self-escort.

Endorsed study: four independent triggers. For Group 1 combinations, the DGT electronic office requires a feasibility and road-safety study signed by a chartered engineer and endorsed by the professional body when just one of these circumstances applies: combination made up of singular elements; maximum mass in transport position above 300 t; combination meeting the requirements to circulate under self-escort; or cargo overhang above 3 m. Any one of the four, on its own, triggers the obligation. Treating the 300 t threshold as the only trigger is the most frequent mistake in budgets by shippers starting out in heavy transport.

The study justifies simultaneous transport, sets sketches of the combination in transport position with axle masses, locates the centre of gravity, and describes stowage and lashings. Without it, the application is not admitted for processing.

Self-escort: default authorisation or additional study. If the combination exceeds 300 t or 3 m of overhang, the Subdirección General de Gestión de la Movilidad y Tecnología authorises by default every stretch of the itinerary under self-escort — the endorsed study already covers the safety analysis and no extra documentation is needed. Below those two thresholds, an operator that still wants self-escort for the whole route files a specific study for eligible combinations. Eligibility is dimensional: length above 65 m and/or width above 5 m, values at which the Agrupación de Tráfico de la Guardia Civil accepts circulation without an external pilot vehicle. In Catalonia, the SCT instruction of May 2024 applies parallel criteria for Servei Català de Trànsit authorisations.

With the technical documentation framed, the next question is administrative: which type of ACC is requested, and whether one is enough or two are needed.

Permits: when one ACC is enough, when two are needed

The rule is not "always two ACCs for any Catalan crossing". It depends on the authorisation category and the route:

• Operation entirely within Catalonia → SCT ACC, single authorisation.
• Inter-regional operation with generic or specific ACC → the DGT ACC can cover the entire itinerary when the operation runs partly through territory outside Catalonia; DGT regulations themselves contemplate that validity under defined conditions. A single authorisation in these cases.
• Inter-regional operation with exceptional ACC whose itinerary includes Catalonia → the DGT ACC cannot include roads in Catalonia, the Basque Country or Navarre. In this scenario, two independent authorisations: DGT ACC for the non-Catalan stretches and SCT ACC for the Catalan stretches.
• Operation also crossing the Basque Country or Navarre → additional authorisation from the Dirección de Tráfico del Gobierno Vasco or the Servicio de Tráfico del Gobierno de Navarra (with the Navarrese AP-68 as an exception managed by the DGT).

Each authority independently assesses the stretch under its jurisdiction, sets specific conditions and issues a separate resolution.

Escort: pilot vehicle and authority officers

Indivisibility determines dimensions; dimensions determine accompaniment. Under the DGT regime — applicable to stretches outside Catalonia, the Basque Country and Navarre (with the Navarrese AP-68 as an exception managed by the DGT) —, the typical thresholds are: private pilot vehicle mandatory for combinations with width above 3.00 m or length above 20.55 m; accompaniment by authority officers for width ≥ 5.00 m or combinations the authority considers critical. Under the SCT Catalan regime, the specific thresholds — set after the May 2024 instruction — differentiate departure communications and Mossos d'Esquadra accompaniment under their own parameters.

The escort force changes with the territory: Mossos d'Esquadra in Catalonia, Guardia Civil de Tráfico in territory without transferred traffic, Ertzaintza in the Basque Country, Policía Foral in Navarre (with the AP-68 under the DGT).

Three administrative lead times not to confuse

An operation with indivisible cargo and ACC has three distinct lead times that the official DGT documentation keeps separate. Confusing them leads to planning the operation with insufficient time:

Professional planning covers the three lead times in series, not in parallel: the ACC is resolved first, the start-of-trip notice is sent on the agreed date, and the escort or self-escort request goes with the operational closure of the window.

Documentation accompanying indivisible cargo

An operation with indivisible cargo requires a documentation package travelling with the convoy that the driver must be able to present on request by the authority:

• ACC — from the DGT, the SCT or both depending on itinerary and category —, with approved itinerary, authorised dates and specific conditions.
• Sketch of the combination in transport position, with total dimensions, axle masses, centre-of-gravity location and overhangs.
• Cargo documentation: manufacturer's technical sheet, indivisibility justification when required, declared and verified weight.
• Consignment note under Ley 15/2009 (LCTTM) for national transport, or CMR Convention for international.
• Endorsed feasibility study when any of the four triggering situations applies.
• Start-of-trip notice to the corresponding authority at least 24 hours in advance, in specific or exceptional ACC.
• Confirmation of accompaniment or self-escort when it applies, identifying the force and time window, request filed at least 72 hours in advance.

The absence of any of these documents at the time of a roadside check can stop the convoy. The professional operation closes the package before departure; never during.

The role of the gestor de transporte

Every road freight transport company with an MDP card must have a gestor de transporte qualified under the Reglamento de la Ley de Ordenación de los Transportes Terrestres (ROTT, RD 1211/1990). Article 111 of the ROTT regulates the link between gestor and company — how they must be contractually bound and under which regime —; article 112 details the functions: real and continuous direction of the transport activity, applying for authorisations, supervising documentation, validating itineraries, responding to authorities. The reform introduced by RD 70/2019 updated the link regime and tightened the requirements for professional competence.

For the shipper, the existence of a stable gestor de transporte at its carrier is the assurance that the administrative chain of every operation is covered by a person with direct legal responsibility. A company without a qualified gestor, or with an unstable link, should not be moving indivisible cargo — and indeed a deficient link can entail loss of the MDP authorisation through a very serious infringement under the LOTT.

How we approach this at PASTOR

Sixty years moving indivisible cargo to and from the Port of Barcelona leave something measurable: a stable gestor de transporte with current qualification, active MDP authorisation, own fleet with vehicles homologated for Group 1, documentation package closed for every operation before departure from the workshop, and a standard dual SCT + DGT coordination procedure for inter-regional itineraries.

For each operation with indivisible cargo we prepare: technical classification of the cargo (indivisible, assimilated or exception), appropriate authorisation category according to itinerary and applicable regime (DGT or SCT), sketch of the combination in transport position with axle masses, endorsed study when any of the four triggering circumstances applies, authorisation application to the competent authority or authorities, start-of-trip notice within the deadline, escort coordination with the force corresponding to the territory, and prior communication to road holders. The shipper holds a single point of contact: ours.