
AXYS®ABF-260/100W PA6 V0 Low Profile Installation Manual Rev 1.1
202103/ABFPA6VOLP_IM_1.1 11
PREPARING FOR INSTALLATION
It is assumed that the installation site (e.g. tunnel) has
been the subject of extensive acoustic analysis prior to the
actual installation. The analysis should have assessed the
acoustic conditions in the tunnel and defined the operating
scenarios (Local/All call, traffic speed, ventilation active/
inactive etc) for the PA/VA system. The minimum speech
intelligibility requirements must be met for each scenario.
The acoustic properties of the tunnel’s interior surfaces
(acoustic absorption and scattering coefficients) and the
expected background noise levels due to the traffic and/
or ventilation system should also have been established.
More information regarding the acoustic design
procedure, including design guidelines, is available at
www.axystunnel.com.
Various acoustic modelling software applications are
available; for example CATT-Acoustic®modelling is suitable
when accurate predictions of the STI (Speech Intelligibility
Index) are necessary.
Nearly all tunnel installations will need to employ multiple
ABF-260 units to obtain satisfactory sound coverage.
The acoustic design procedure will have identified the
number of ABF-260s required and the optimum physical
location for each to accurately achieve the desired acoustic
coverage. In particular, the height above the roadway, and
any mechanical mounting angles will have been specified.
50 m linear spacing between units is typical, but two or
more units may be required at each position when the
overall tunnel width is more than 12 m.
The installer should confirm that he/she has all necessary
information relating to the location and physical
orientation of all ABF-260 units making up the system. It
is important to recognise that even small deviations from
the calculated positions can adversely affect the desired
acoustic coverage.
MECHANICAL INSTALLATION
Location
The ideal mounting situation for the ABF-260 is with the upper
surface of the horn secured flush to the mounting surface (the
tunnel roof). If the roof is curved, a totally flush fitment may
be unachievable; see “Fixing to a curved roof” in this section.
Tunnel infrastructure may also preclude a flush fitment; see
“Non-flush installation” at the end of this section.
The ABF-260 should be mounted so that the flare of the
horn faces the oncoming traffic. If it is found that tunnel
infrastructure items (lights, traffic signs, fans, etc.) are
within 5 m of the horn flare and in line with the horn,
an alternative mounting location should be found. In such
cases, the installer must contact the acoustic designer for
guidance before proceeding with the installation.
Do not mount the ABF-260 in the vicinity of
high pressure deluge / sprinkler system water
outlets. Any water outlets of the sprinkler
system should not spray directly into/onto the ABF-260.
Fixings
Fixing is via the ten 9 mm mounting holes around the edge
of the upper surface. It is advised to use the 8 fixing points
located in pairs at a distance of respectively 75, 508, 782 and
947 mm from the front side of the unit as indicated in fig.2.
M8 screws or bolts should be used, of a length appropriate to
the type of mounting employed (see below).
The weight of the ABF-260 is 18 kg, and a safety
factor of 4 should be allowed when checking
the safe load capability of the mountings.
The diagram on the following page (fig.2) gives the
dimensions required for marking the mounting hole
locations on the roof.When marking out for the holes, take
care that the hole positions take into account any mounting
angle specified for the horn by the acoustic specification.
The roof mountings can be in the form of threaded inserts,
commercially available as “Rawlbolts”, or similar. An alternative
approach is to inject a fire resistant chemical screw fixing
compound into the hole and fix the loudspeaker using 8 mm
diameter hex-head coach screws. The horn may need to be
supported during the compound’s setting phase (curing time).
3. INSTALLATION GUIDE