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Space requirement for cold milling
ASR 5.2 in use

Before the introduction of ASR 5.2, the required working space around cold milling machines was always a cause for discussion. The milling service providers organised in the VESF welcome the regulations that are now in place because it is now more concrete than ever before how much space must be provided for personnel. For the concrete implementation, the VESF provides the following information to help with the planning of construction sites.

Machine type influences space requirements

When planning, it should be noted that the machine type has a considerable influence on the work process. Figure 1 shows that the difference between the machine width of a cold milling machine and the milling width depends on the machine type. However, the basic design of the machines always means that space is required on both sides for technical reasons.

Fig. 1: Schematic representation (top view) of typical cold milling machines

On small milling machines, the milling drum is located on the right-hand side at the rear of the machine, between the wheels of the rear axle. These machines load the milled material to the rear, so they are "rear loaders". Their maximum milling width is 1 m.

On compact milling machines (milling width 1.0 m - 1.3 m and front loading of the milled material = front loader), the milling drum is also located in the area between the rear wheels or crawler tracks.

On large milling machines, the milling drum is located in the centre of the machine. On the "zero side" (on the right in the direction of travel), the milling drum always extends to the edge. Next to it is the edge protector. It covers the side of the milling rotor and is typically 15 - 20 cm wide.

Fig. 2: Schematic representation (rear view) of a large milling machine with distances AL and AR

From the design, typical distances AL and AR result in all machine classes for the distance from the milling edge to the outer edge of the machine. These distances must be taken into account in any planning.

In addition to the space for the machine, the working space for the operating personnel must be planned. Here, too, a distinction must be made between machine classes.

Space requirements for small and compact milling machines

Small and compact milling machines are normally operated by one person sitting or standing on the operator's platform. In the planning, a working space with a minimum width of BM = 40 cm must be calculated for this person next to the operator's platform. The reason: drivers often bend over the backrest to get a better view of the milling edge or obstacles (Fig. 3).

Figure 3: Small and compact milling machines are usually operated by one person. For this person, a working space with a minimum width of BM = 40 cm must be provided next to the operator's platform.

Space requirements for large milling machines

The large milling machines are usually operated by teams of 2. One person is on the operator's platform, steering the machine and operating the discharge conveyor to load the milled material. The second person on the ground runs along with the machine (walk-behind operation). The tasks of this person include, for example:

- the continuous quality control
- changing the cutting tools (together with the driver)
- the organisation of water replenishment
- assisting the driver, e.g. in the area of transition constructions
- cleaning the lane
- communication with the site management
- the fine adjustment of the milling depth

For walkers, ASR 5.2 provides for a working space around the machine with a minimum width BM = 80 cm.

Figure 4: Large milling machines are usually operated by teams of 2. For the person on the ground, a working space with a minimum width BM = 80 cm must be provided next to the machine.

Space requirements for cabin milling machines

Meanwhile, large milling machines with cabs are also available on the market, but their population is still small. The vast majority of large milling machines in Europe have a "classic", i.e. open operator's platform. If milling machines with cabs are required for a construction site, they must be explicitly requested in the tender.

The cabin of these machines can be moved laterally so that it protrudes over the milling edge on both sides (Fig. 5) and the driver has a view of the milling edge. Accordingly, this results in slightly different dimensions AL and AR for the distances from the milling edge to the outer edge of the machine, which is now the outer edge of the cabin.

Fig. 5: Large milling machine with cabin

As the cabins have a window from which the personnel can lean out, a working space BM = 40 cm next to the outer edge must always be allowed for when using cabin machines.

Total clearance

The space from the milling edge to the barrier, which must be provided as a minimum in the planning, is made up of the distances AL or AR (machine), the distance BM (working space operator) and the safety distance SQ. Table 1 shows typical values for AL / AR and BM for the corresponding machine classes using common models as examples. For planning special construction measures, corresponding dimensions of current machines can be requested from the VESF or the manufacturers.

Table 1: Clearance dimensions of typical cold milling machines, as of October 2019

The choice of machines does not affect the safety distance SQ. This size results from the type of barrier selected (vehicle restraint system or guide beacons, etc.) and the maximum permissible speed in the construction site area.

Possible special regulations for special requirements

If there is little space available, the VESF always advocates full closure in case of doubt. It not only ensures more safety, but also higher quality. Last but not least, a full closure often leads to faster completion of the construction work.

If a full closure is not possible, special arrangements have to be made that involve additional expenditure. For example, when using a large milling machine with a cabin, it would be conceivable to prohibit all construction site personnel from entering the area facing the traffic and also not to open the cabin window. With these precautions, BM on the side facing the traffic could be reduced to zero. In doing so, the tendering authorities must be aware of the fact that the restriction of freedom of movement can also result in a loss of quality, for example on the precision when setting a milling track, for which the view out of the cabin window can be important.

Such specifications must already be announced in the tender and require thorough preparation and instruction of all persons involved in the measure - not only the milling personnel. It is also essential that appropriately authorised personnel are present on site during the entire milling process to ensure compliance with the specifications.

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