Difference between ACC and SCT in special transport

Until 1 May 2024, moving a 180-tonne transformer from the Port of Barcelona to Zaragoza required a single authorisation: the Complementary Circulation Authorisation (Autorización Complementaria de Circulación, ACC) issued by the Dirección General de Tráfico. The same convoy today requires two — one from the Servei Català de Trànsit (SCT) for the stretch within Catalonia, the other from the DGT for the rest of the route. The ACC SCT difference is not administrative: it is jurisdictional. Who governs each metre of road has changed.

The 1 May 2024 reform

Authority over traffic and road safety has been a transferred competence to Catalonia for decades. The missing piece was the special circulation authorisation: for years the DGT continued to process it even for Catalan itineraries. That practice ended on 1 May 2024.

From that date, ACCs granted by the DGT whose itinerary runs partly or wholly through Catalonia are not valid on the Catalan road network under the general regime. The operational rule for a new application: any convoy that will circulate on Catalan roads needs an SCT authorisation, except for the residual case foreseen in the DGT regulations themselves for generic or specific authorisations with a partial stretch outside Catalonia, which is detailed below.

DGT authorisations granted before 1 May 2024 remain valid until their expiry date, only for the itinerary, combination and cargo originally authorised. Any new operation — even with the same vehicle in the special-transport regime (VERTE) — is now submitted to the SCT. For new applications, the jurisdictional border is absolute.

The reform brought a second milestone, already under the dual regime: with the entry into force of Orden PJC/780/2025, from 23 October 2025 euromodular combinations up to 72 t total mass and 32 m long — the so-called megatrucks — no longer need prior authorisation to circulate, although they must comply with DGT technical conditions and, in Catalan territory, with the suitable itineraries defined by the SCT.

What each authorisation covers: ACC and SCT compared

An ACC is the administrative document that allows a vehicle or combination to exceed the maximum values for mass and dimensions in the Spanish General Vehicle Regulation (RD 2822/1998, Annex IX). Both the DGT and SCT documents are ACCs. What changes is the issuing authority and the covered territory.

Before getting into categories, two terms that run through the entire regulation should be fixed:

• Indivisible cargo: cargo that cannot be divided into two or more parts without unnecessary cost or risk of damage. A transformer, a bridge section, a wind turbine nacelle.
• Cargo assimilated to indivisible: a set of elements of the same nature and destination (poles, beams, logs, profiles) whose individual pieces fit within the ordinary regime, but whose grouping exceeds the RGV limits.

The distinction is not academic: it determines the maximum authorisable mass and the number of unitary loads admitted by each ACC modality.

Categories: generic, specific, exceptional

The three categories are common to the DGT ACC and to the SCT authorisation. The thresholds are set on the combined vehicle and load in transport position (tractor + platform + cargo):

The generic authorises a vehicle fleet with no fixed itinerary. The specific ties the authorisation to a concrete itinerary. The exceptional covers the rest: 250 t transformer, 6 m width, long overhangs. Everything the RGV does not contemplate. The ceiling of the exceptional is not codified: it is set case by case by the endorsed feasibility study and the report of the road holders.

For cargo assimilated to indivisible by length (poles, beams, logs), the maximum authorisable mass stays at 44 t — the Annex IX RGV ceiling for articulated combinations or road trains with 5 or more axles. Total combination length must exceed 18 m: below that threshold, the SCT does not process authorisation under the length-assimilated route.

Endorsed feasibility study: when it is mandatory

For Group 1 combinations (special-transport vehicles and their combinations), the application requires a feasibility and road-safety study signed by a chartered engineer with the relevant qualification. Four situations trigger it, any one of them on its own:

1. Combination made up of singular elements (cargo assimilated to indivisible).
2. Maximum mass of the combination in transport position above 300 t.
3. Operation with self-escort (no external pilot vehicle).
4. Cargo overhang above 3 m.

The study includes justification of element simultaneity, sketch of the combination in transport position with dimensions and axle masses, location of the centre of gravity, stowage conditions, lashings and supports. Without it, the application is not admitted for processing. Treating the 300 t threshold as the only trigger is one of the most frequent mistakes by non-specialised shippers.

The exceptions to indivisible cargo — goods that can be split but are transported grouped in one combination whose total mass does not exceed 100 t — follow a lighter administrative regime, without the need for an endorsed study under this route.

Operational differences between the DGT ACC and the SCT authorisation

The DGT ACC covers the state network outside Catalonia, the Basque Country and Navarre (with the exception of the AP-68 in Navarre, which the DGT does manage). The SCT authorisation covers any circulation that touches Catalan roads. Both share structure, categories, endorsed-study thresholds and sketch format.

What changes between one and the other:

• Processing platform. DGT through the electronic office of the Ministerio del Interior; SCT through the Trámites Gencat portal of the Generalitat.
• Coordination with escort. SCT channels directly the request for Mossos d'Esquadra accompaniment when it applies. DGT requires separate coordination with the Guardia Civil de Tráfico.
• Reference road network. Each authority evaluates the itinerary against its network: bridge clearances, time restrictions, ongoing works, urban critical points.

Map of competent authorities after the 1 May 2024 reform. Catalonia as the SCT's sole jurisdiction. The Basque Country and Navarre with their own regional authorities. The AP-68 crosses Basque and Navarrese territory but remains under DGT competence — the only exception to the territorial principle. Port BCN marked as origin of most inter-regional convoys to Aragón, Comunitat Valenciana, France and the rest of the state network.

Practical cases: when you need ACC, SCT, or both

The operational rule is simple: as many authorisations as traffic authorities whose territory the convoy crosses. The authority that authorises circulation does not always coincide with the force that escorts — that point is covered below.

When the itinerary crosses two authorities, the application is submitted to each separately. Each authority evaluates the stretch under its jurisdiction — type of road, bridge clearances, critical crossings, time restrictions — and issues an independent resolution. The convoy cannot start the trip until every resolution is favourable.

Lead times: rule vs reality

The maximum legal processing time is 3 months from submission of the application, deducting the report times of the road holders and the periods to correct the application. That is what the regulation says.

In practice:

• Generic without a complex itinerary: 7-15 working days.
• Specific with crossings through critical sections (bridges, urban areas, restricted zones): 30-60 days.
• Exceptional with mass above 100 t or width above 4 m: 45-90 days, with endorsed technical study.

Costs break down into administrative fees and, if delegated, external management. DGT fee: €30-80 depending on category. SCT: €280-450 per authorised working day. Inter-regional operation: fees to both authorities, two management workflows.

An operational recommendation for inter-regional itineraries: although the regulation does not require a sequence, in practice it is advisable to resolve the DGT ACC first for non-Catalan stretches and, with that resolution in hand, submit the SCT application for the Catalan stretch. The reason is practical: the final viability of the itinerary tends to depend on the DGT stretches, and the SCT can adjust its authorisation to the real time window of the convoy. Simultaneous submission is legally possible, but more exposed to mismatches between resolutions.

Mistakes that stop a convoy

Without SCT, the convoy is in breach from the first Catalan metre.

Relying on a current DGT ACC to start a new operation in Catalonia. ACCs granted by the DGT before 1 May 2024 remain valid for the itinerary, combination and cargo originally authorised, until the document expires. They do not enable new operations. A specific authorisation granted in February 2024 covers the operation that prompted the application, not new cargoes or new routes with the same vehicle.

Assuming the DGT covers the entire state. Catalonia, the Basque Country and Navarre (except the AP-68) have their own authority. The novelty of May 2024 is Catalonia. The other two have had transferred competence for decades.

Confusing the authorising authority with the escorting force. SCT authorises, Mossos escort. DGT authorises, Guardia Civil escorts. Dirección de Tráfico GV authorises, Ertzaintza escorts. Servicio de Tráfico Navarra authorises, Policía Foral escorts. They are different functions with different procedures.

Treating the 44 t limit as an absolute ceiling. The ordinary RGV regime is 40 t; the 44 t figure applies to articulated combinations or road trains with 5 or more axles, and is the ceiling for cargo assimilated to indivisible by length. For properly indivisible cargo (a transformer, a bridge section), the authorisable mass comfortably exceeds that threshold: the specific reaches 110 t and the exceptional has no codified ceiling, subject to an endorsed study.

Forgetting the four conditions of the endorsed study. The common error is to associate the study only with the 300 t threshold. A cargo overhang above 3 m, a self-escorted operation or a combination of singular elements is enough to make it mandatory. A single condition triggers the requirement.

Who authorises, who escorts

The authorisation is the document. The physical operation needs more.

The Spanish General Traffic Regulation (Annex III) distinguishes two levels of accompaniment, each with its codified threshold:

• Pilot vehicle (private accompaniment, driven by qualified personnel from the carrier itself or a specialised company): mandatory when width exceeds 3 m or length exceeds 20.55 m. It is the most frequent accompaniment in special transport: it leads the convoy, warns other road users, manages manoeuvres at junctions.
• Accompaniment by authority officers (effective police escort): mandatory when width reaches or exceeds 5 m. The traffic authority may require it situationally for exceptional lengths or critical urban stretches, even when no fixed threshold is codified.

The escort force changes with the territory:

• Catalonia: Mossos d'Esquadra. Request channelled through the SCT when the authorisation is obtained.
• Basque Country: Ertzaintza. Separate request coordinated with the Dirección de Tráfico del Gobierno Vasco.
• Navarre: Policía Foral. Separate request coordinated with the Servicio de Tráfico del Gobierno de Navarra.
• Rest of Spain: Guardia Civil de Tráfico. Coordination with typical advance notice of 7-15 days for exceptional convoys.

When a convoy crosses Catalonia and enters the rest of Spain, the escort change happens at the regional border: Mossos to the boundary, Guardia Civil thereafter. Planning between both forces is done with both authorities before departure.

How we coordinate this at PASTOR

Sixty years at the Port of Barcelona — 41°22'N · 02°11'E — leaves something measurable: zero convoys stopped at the regional border since the reform. Dual SCT + DGT coordination is standard procedure for any operation crossing into Aragón, Comunitat Valenciana or France.

For each inter-regional operation we prepare: technical study of the combination, sketches with axle masses, itinerary viability checked with road holders, SCT application, DGT application, prior communications to authority officers, escort coordination with Mossos, Guardia Civil, Ertzaintza or Policía Foral depending on the stretch. The shipper holds a single point of contact: ours. Two — or more — administrative resolutions running in parallel.

When the time comes to depart, the convoy carries the complete documentation: DGT ACC for the non-Catalan stretches, SCT authorisation for the Catalan stretch, stamped sketch, registered prior notice, escorts confirmed. The border stops no one.