General Principles for the Design of the Cross-section - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 12

An exception permit is to be obtained from the BMVBW (federal ministry for transport,
building and town development) in each individual case for the application of the height
of 5 100* mm above TOR according to Fig. 1-8.

In contrast to the details described until now, the safety space in S-Bahn tunnels has to
be at least 80 cm wide. For the height and width of the escape route, the dimensions of
2.20 m · 1.20 still apply.
Fig. 1-9 shows as an example the guideline detail from Ril 853 for a 2-track S-Bahn tunnel
with rectangular cross-section.

1.2.4 Construction of rail tunnels
The fire and civil protection requirements for the construction and operation of rail tunnels
are laid down in the guideline of the federal railway authority (EBA) with the same name
from 15 August 2001. The following section describes some important design principles
from this guideline. More detailed information can be found in the guideline.

Fire duration and temperature curve. In order to minimise the depth of concrete spalling
that could endanger passengers, a curve of temperature against time is to be assumed for
design purposes (Table 1-1).

Table 1-1 Temperature curve depending on fire duration according to EBA.

Fire duration [min] 0 5 60 170

Temperature [°C] 0 1200 1200 0

These data can be used to determine the additional stresses, which have to be resisted by
constructional measures (for example additional layers of reinforcement).
Safe areas, escape routes, emergency exits. Each track is provided with its own escape
route next to it, as has already been mentioned in the description of the various planned
uses. Localised narrowing of the escape route is to be avoided or in exceptional cases
limited to a length of 2.0 m and a depth of 0.3 m. Handrails should be provided on all
escape routes.
For the design and layout of escape shafts and tunnels, the limited physical capabilities
of frail people and those with disabled mobility should be considered. Shafts should not
exceed a level difference of 60 m and if the level difference is more than 30 m, should
be equipped with a lift with dimensions 1.1 · 2.1 m. Stairs should be suitable for people
passing and for the transport of stretchers according to DIN 13024.

Escape tunnels must have a cross-section of at least 2.25 m · 2.25 m, and not exceed a
maximum gradient of 10 % and a maximum length of 150 m if they do not reach the open
air directly but up a shaft. For lengths of more than 300 m long, rescue shafts must be ac-
cessible for ambulances.
Rescue areas and access roads. All exits and portals of the tunnel must be accessible by
road. For long tunnels, a rescue area is to be provided at each portal and emergency exit.
For shorter tunnels, one rescue area is sufficient.