Building Design and Construction Handbook - Merritt - Ventech!

VERTICAL CIRCULATION 16.15
most attractive to traffic and where convenient for passengers. The facility should
be designed and signed in a manner that makes it apparent where the visitor will
find the escalator. Since escalators are devices that will fail on occasion, the designer
must provide alternative transportation (usually adjacent stairs) for times
when the escalator is unavailable for passenger use. More importantly, where escalators
will be operating at capacity as a result of specific programmatic considerations,
the designer must plan alternative routing for times when one or more
escalators is under repair. In retail applications, marketing needs generally motivate
selection of escalator locations.
In design of a new building, adequate space should be allotted for escalators.
Generous areas should be provided at both loading and unloading areas. Special
consideration should be given to the possibility of a disaster resulting at a constricted
exit from an escalator when pedestrian traffic is restricted below the escalator’s
capacity in the path of travel. Similarly, planning of landing areas should
consider both queuing space and what happens when an escalator is stopped for
some reason while pedestrian traffic continues. In addition, before stacked escalators
are planned for an arena, stadium, or other facility having exit peaks, the potential
for pedestrian traffic jams should be carefully weighed. If exiting traffic is very
heavy in a stacked escalator system, upper levels can easily fill lower-level escalators,
creating a jam at the escalator entries and leaving little space for lower-level
pedestrians.
For an escalator installation in an existing building, careful study should be made
to determine the necessary alterations to assure adequate space and supports.
16.4.6 Structural Considerations in Escalator Installation
Floor-to-floor height should be taken into account in determining loads on supporting
members. Generally for floor-to-floor heights of less than 20 ft, the escalator
truss need be supported only at top and bottom. Increased vertical rise can create
the need for intermediate support points. A structural frame should be installed
around the escalator well to carry the floor and wellway railing.
Inasmuch as an escalator is a mechanical device, careful consideration should
be given to the potential for noise and vibration in design of the escalator structural
supports. Where necessary, the escalator can be mounted on vibration-isolating
devices to help reduce noise and vibration.
16.4.7 Escalator Installation
Design of escalators permits a vertical variation of 1 ⁄2 in in the level of the supporting
beams from the specified floor-to-floor height. The escalator is shimmed to
bring it level. If variations in elevation exceed 1 ⁄2 in, installation is difficult and
much time will be lost. To allow for variations in overall escalator length, truss
extensions can be provided.
Trusses generally are brought to the job in one section. There, they are raised
into position with chain hoists, either through an elevator shaft or on the outside
of the building. Typically, the escalator manufacturer does not furnish either the
exterior truss cladding or the wellway railings and accessories. Because of the need
for economy, escalator manufacturers design for minimal weight in the truss cladding.
Hence, care should be taken to coordinate carefully the desired design with
the escalator manufacturer.