BSB-Saugbagger & Zweiwegetechnik

Updated: August 2026 – Not everything that runs on rails is a locomotive. A considerable part of railway construction is done by machines that actually come from the road. BSB-Saugbagger & Zweiwegetechnik carries two of these technologies in its name. This page explains what lies behind them, how such vehicles are numbered and why they are missing from every sightings archive – even though they belong there.

What is BSB-Saugbagger & Zweiwegetechnik?

BSB-Saugbagger & Zweiwegetechnik is a German company in construction technology in the track area. The company name is unusually precise: it names not a line of business but two specific technologies. Saugbagger (vacuum excavators) stand for contact-free removal of soil, Zweiwegetechnik (road-rail technology) for machines that can run on road and rail.

From this, the operating profile can be derived quite well: work on and next to the track, where services lie in the ground and heavy equipment has to get onto the track at short notice. Exactly where, for whom and with how many machines – those are project-dependent details that are deliberately left out here.

Recognising road-rail vehicles in the field

Of all rail vehicles, road-rail vehicles are the easiest to identify – provided you know what to look for.

How to identify unfamiliar vehicles systematically is shown in the guide to identifying classes – the approach works for ancillary vehicles just as it does for locomotives.

Ancillary vehicles: a vehicle category of their own

Ancillary vehicles aren’t a special case but a class of their own with their own rules. They are used for construction and maintenance, not for carrying passengers or goods. This results in differences that matter for documentation.

Feature	Regular vehicle (locomotive, multiple unit, wagon)	Ancillary vehicle
Purpose	Carrying passengers and goods	Construction and maintenance of the infrastructure
Start of number	digit sequence depending on type	in Germany starting with 99
Position of number	Data panel on the side of the vehicle	often small, on the frame or body
Use in rail traffic	approved without restriction	only to a limited extent, usually in closed areas
Livery	brand or group colour	warning livery in yellow or orange
State of documentation	extensive	thin – every sighting is worthwhile here

The last row is the real incentive. While thousands of pictures exist of every series-built locomotive, many construction machines are barely documented. Typical examples are road-rail excavators such as the Atlas 1604 ZW and the Liebherr A 900 C ZW, as well as road-rail track machines such as the Plasser & Theurer 08-275/4 ZW-Y.

What a vacuum excavator does in railway construction

Cables run along practically every railway line: signalling and telecommunications lines, power supply, data connections. They lie in cable ducts or directly in the ground, and they aren’t always where the plans say they are. A conventional excavator would tear them apart.

The vacuum excavator works with powerful suction instead: it removes the soil layer by layer and sucks it into a container, without acting mechanically on the cables. This makes it possible to expose cables, relocate foundations and open shafts without bringing operations to a standstill through cable damage. That’s exactly why this technology is so widespread in railway construction – and why some companies put it in their name.

You’ll find comparable combinations of construction technology and a railway connection at GBM Gleisbau Maas, Rhomberg Sersa Bahntechnik and STRABAG Rail Operations.

How to document a construction machine sighting

With locomotives, the routine is well established: number, keeper, location, time. With construction machines, the information is distributed differently, and if you only look for the familiar data panel, you’ll come away empty-handed. Three additional sources matter most here: the manufacturer’s type plate, the lettering on the body and the small number on the frame.

There’s also a practical point: construction machines move slowly and often stand still for minutes at a time. That gives you more time than with a passing train – use it for several shots from different angles rather than a single picture.

An extra tip for your archive: don’t file construction machines under the name of the construction company, but under manufacturer and type. Construction companies change from contract to contract, but the machine stays the same – and that’s the only way you’ll find it again on its next job in a different region.

Safety: construction machines work where you’re not allowed to be

Common mix-ups

• Road-rail vehicle and locomotive – a vehicle with rail wheels is far from being a traction unit.
• Warning livery as company colours – yellow and orange are safety colours, not brand identifiers.
• Excavator on a low-loader as a road-rail machine – only its own rail running gear makes the difference.
• Ancillary vehicle number as locomotive number – different number ranges, different rules.
• Machine manufacturer as operator – the name on the machine is usually the manufacturer’s, not that of the company using it.

How to enter such vehicles correctly in an archive is described in the guide to reporting sightings.

Verdict

Road-rail technology and vacuum excavators stand for a part of railway operations that is hardly perceived as railway at all – and yet takes place on rails every day. For people documenting the railway, that’s an opportunity: few photograph these machines, many of them only exist in small numbers, and their deployments rarely last long.