Reference
Heavy Transport Technical Guide: Lowbeds, Axle Lines and Permits
A technical reference from Zagrebački transporti (ZGT): trailer types and deck heights, axle-line configurations, legal limits for truck width, height, length and weight, plus permit procedures and driving-ban schedules in Germany, Austria, Slovenia and Croatia. Every figure comes from the day-to-day operation of our own fleet since 1996.
Trailer types and deck heights (lowbeds and more)
The choice of trailer determines the overall load height and therefore whether an over-height permit is required. Reference values from our fleet:
| Vehicle type | Deck height | Payload | Typical use |
|---|---|---|---|
| Lowbed semi-trailer (semi-lowloader) | approx. 40–55 cm | up to 40 t | Excavators, wheel loaders, rollers, cranes, compact machinery |
| Telescopic semi-trailer | approx. 85–100 cm | up to 35 t | Girders, pipes, masts, over-length cargo up to approx. 30 m |
| Lowloader with wheel wells (excavator loader) | approx. 30–40 cm | up to 45 t | Over-height machinery, tracked excavators, drilling rigs |
| Flatbed / platform trailer | approx. 120–150 cm | up to 27 t | Containers, steel structures, palletised project cargo |
| Modular trailer (axle lines) | from approx. 90 cm, hydraulically adjustable ±30 cm | up to 100 t and more | Transformers, boilers, plant components, wind turbine parts |
Axle lines: configuration and payload
Modular trailers are calculated by axle lines. One axle line carries about 12 t of payload; what matters most is the allowed axle load on the planned route, since bridges limit load distribution.
| Configuration | Payload (guideline) | Application |
|---|---|---|
| 2 axle lines | approx. 24 t payload | Short, compact loads; low deck height |
| 3 axle lines | approx. 36 t payload | Standard for construction machinery over 30 t |
| 4 axle lines | approx. 48 t payload | Heavy presses, generators, gearboxes |
| 6 axle lines | approx. 72 t payload | Transformers, boiler sections, reactor segments |
| 8+ axle lines (coupled) | 100 t and more | Project cargo with route survey and bridge assessment |
Legal limits: truck width, height, length and weight
Up to these values, no permit is required. Above any of them, the move counts as an oversized or heavy transport.
| Dimension | Limit | Note |
|---|---|---|
| Truck width | 2.55 m | 2.60 m for refrigerated vehicles; a permit is required above this |
| Truck height | 4.00 m | Germany has no fixed legal height limit, but 4.00 m is the practical threshold |
| Semi-trailer length | 16.50 m | Road train 18.75 m; above this, it becomes an abnormal load |
| Gross weight | 40 t | 44 t in combined transport (pre/on-carriage to a terminal) |
| Axle load | 10 t single axle / 11.5 t drive axle | Decisive for bridge assessments |
Permits and escort
- Germany – VEMAGS (§ 29(3) / § 46 StVO): the federal states' central online system. Typically 5 to 20 working days, considerably longer with a bridge assessment.
- Austria – § 101 KFG: permit from the relevant provincial authority, 5 to 15 working days, a route check is required.
- Slovenia – DRSI / DARS: 3 to 10 working days.
- Croatia – Hrvatske ceste / HAC: 3 to 7 working days.
- Escort: BF2 from approx. 3.00 m width, BF3 from approx. 3.50 m width or 4.20 m height, police escort for road closures and contraflow guidance — the exact requirement is set out in the permit.
Driving bans: when can heavy transports run?
- Sunday and public-holiday driving ban in Germany: 0:00–22:00 (§ 30(3) StVO) for vehicles over 7.5 t
- Summer holiday ban: Saturdays 7:00–20:00 from 1 July to 31 August on listed motorways
- Abnormal loads often run only at night, typically between 22:00 and 6:00, when required by the permit
- Austria: weekend and night driving bans plus sectoral bans in Tyrol
- Slovenia: driving ban on Sundays and public holidays 8:00–21:00, plus Saturdays in summer
- Croatia: summer weekend restrictions on coastal routes (A1, D8)
Frequently asked questions
- When does a transport count as a heavy transport?
- As soon as any dimension exceeds 2.55 m width, 4.00 m height, 16.50 m length (semi-trailer) or 40 t gross weight, the transport counts as an oversized or heavy transport and requires a permit.
- When are heavy transports allowed to drive?
- The driving window is set out in the permit. Night moves between 22:00 and 6:00 are common. In Germany, a driving ban applies on Sundays and public holidays from 0:00 to 22:00, plus the Saturday summer holiday ban.
- How tall is a lowbed trailer?
- A lowbed semi-trailer has a deck height of roughly 40 to 55 cm, and a lowloader with wheel wells starts at about 30 cm. This allows machinery up to about 3.5 m in height to be transported without exceeding legal height.
- How much payload does one axle line carry?
- One axle line of a modular trailer carries around 12 t of payload. Three axle lines equal roughly 36 t, six axle lines around 72 t; modules are coupled together for heavier cargo.
- How long does a special permit take?
- In Germany via VEMAGS, usually 5 to 20 working days. For wide or particularly heavy loads requiring a bridge assessment, allow four to eight weeks.
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