**2.3 Inspections**

The preparation of the overall consist is followed by inspections of the individual wagons within the consist. The most notable step is the brake test, which aims to avoid critical malfunctions in the brake system.

Hazards of a malfunctioning brake system include:


In freight trains, the application to and release from the wheel of the individual brake blocks is required to be checked by visual inspection, requiring additional walking times for the pre-departure checks.

The procedure following German regulations as laid out in Ref. [7] (similar regulations are in place, e.g., in the US [8]) consists of the following steps:


The first step was described under preparation. Stages of the brake test set in bold font require a full walk of the train length; in the case of a single operator executing the test, a double walk of the train length is required due to the necessity to return to the leading vehicle. For the maximum European train length of *l* = 750 m. including locomotives, this results in *d l* = = 2·4· 6000 m . At a realistic walking velocity in the track area of *v*walking = 1m/s , this relates to a time consumed just for walking of *t*walking = 100 min

Following German regulations, a brake test has to be executed on each newly assembled train, after adding wagons or changing the direction of the train, and is repeated at least every 24 hours. In certain cases, for example, during a direction change, a so-called simplified brake test is acceptable, which does not check each wagon individually but rather focuses on the continuity of the BP and the braking of the last wagon.

In addition to the brake test, the wagon subsystem is visually inspected for its technical state, for example, the state of the suspension system, as well as for the integrity of the wagon and its load. Since the operator passes by each wagon, this is currently included in the inspection.

### **2.4 Siding operation**

The operation in sidings, as part of the more general shunting operation, is typically executed in order to serve the individual loading points. Wagons arrive in a closed consist to the siding, typically in shunting mode from the last station passed on the way. Shunting operation is executed on-sight, and thus the velocity on the mainline is limited, in the German case, to a maximum of 40 km/h with further restrictions based on infrastructure or a particular operation.

The mainline track between the last station and the siding switch remains blocked during the whole time that the shunter operates on this section of track, as it can only be safely considered free once the shunter returns to the station (**Figure 4**).

#### **Figure 4.**

*Line segment with siding and train motions required to serve it.*

This mode of operation uses a lot of capacity as the line is blocked for two trains, with a typically long stop and pushing operation into the siding, both operated at low velocities.

In the siding, the consist frequently needs to be split up into wagon groups or single wagons, which are then transported with the help of a shunting locomotive to the loading point for processing. After processing at the loading point, the wagons need to return to a collection point to be picked up in the same fashion as they were brought to the siding.

Different designs of sidings exist, listed either as passing siding or station siding, which yield improvements over the basic design. In the former, the line is only blocked for service to and from the siding point; in the latter, a full train movement is possible up to the siding. Both, however, come with significant investments in command, control and signalling infrastructure. This makes such designs only viable for sidings handling large quantities of wagons.
