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The Essex Hotel, San Francisco, CA
Contractor: Ascent Elevator Services Inc.
Major alteration of 19-teens Otis basement winding drum,
swing door passenger elevator. New
Hollister Whitney #44 basement O.D. machine, MCE controls,
V/E sling, platform
& cab and Adams fixtures.
RCB Elevator Consulting, LLC and its associate structural
engineering firm, Eddington Engineering, performed all of
the elevator and building engineering required to make the
conversion. This included performing all field
surveys, elevator design drawing preparation, elevator
structural engineering and owner consultation.
Project Description
The Essex Hotel at 684 Ellis Street in San Francisco,
California was one of the city's early hotels of some
elegance and merit. However, over the years time had
taken its toll and the facility became one of the many
single room occupancy residence hotels that make up the
colorful area of the city known as the Tenderloin. As
a part of the ongoing initiative in San Francisco known as
Care Not Cash, this facility and many others like it are
being renovated to provide supportive housing for the
formerly homeless.
One of the goals of Mayor Newsom's program in housing the
homeless is to make the facilities ADA compliant and
accessible to the disabled. This presents challenges
for converting these older facilities as many of the
structural elements of the buildings limit what can be done,
and this is especially true with respect the elevator.
The ADA law and the elevator code and industry standards
prescribe the minimum car and entrance sizes required to
accommodate a wheelchair and other accessibility devices.
Existing elevators and their hoistways in these older
facilities are typically undersized as compared to these new
standards. The cost of increasing the hoistway size by
moving walls, stairways, etc. and the structural work that
such changes would require, as well as the loss of usable
housing space, make complying with the larger elevator size
requirements impracticable.
Therefore, the city and the mayor's office can establish a
hardship requirement, as allowed by the ADA law, to retain a
smaller elevator car. Certain special measures are
taken to accomplish this. The intent of the code is
for a wheelchair to enter the car and rotate 180 degrees to
exit. These smaller cars won't provide this turning
radius, instead requiring the wheelchair to back out.
To assist in this, a second car operating panel and a mirror
are required at the rear of the elevator car. These
features were provided as part of this elevator remodel
along with full 36" wide, power operated entrances and all
of the other standard accessibility provisions.
Calling this elevator job a modernization is a bit of an
understatement. Modernization is the common industry
term - the technical code term is actually "alteration" -
describing any work short of a full elevator replacement or
new installation. In this job, only the steel
guiderails, machine base and overhead sheave beams were
retained. And these were either modified or
reinforced. For all practical purposes, it's a new
elevator in an existing hoistway and machine room.
The core of the work is converting the elevator from an
obsolete basement winding drum to a modern basement traction
elevator. Note that special care must be taken to
structurally and seismically anchor the new basement
traction drive machine. It is insufficient to simply
bolt the new machine down to the old winding drum machine
base as the new machine weighs less, the new car &
counterweight weigh more and there is no way to certify the
strength of the old machine base anchorage. Keep in
mind, Otis probably didn't include seismic loading when
designing the original anchorage. Therefore, we design
and structurally calculate a completely new machine
anchorage separate from the old base. In this job, it
includes a vertical plate and angle assembly that is
anchored to both the original elevator pit wall and new pit
floor slab. See more discussion on our page,
Winding Drum Elevator Conversions.
Another rather unique feature of this job was to provide a
new car sling, platform and cab that replicate the original
car's feature of having the car sling stile channels inset
into the platform. This allows for a wider functional
car interior in front of and behind the stiles. It
also allows for a wider entrance. This is one of the
tricks to maximizing the car size to unusually small
hoistways. The cab interiors accommodate this with
stainless steel formed channels that are set near to the web
of the stile channels so as to minimize the stiles'
intrusion on the car interior space.
The existing hoistway has a concrete encased building column
in the front left corner, which restricted the width of the
entrances. We dispensed with the usual entrance corner
angle strut to save space and instead suspended the entrance
hanger plates with clip angles and wedge anchors mounted
directly to the concrete column. Another hoistway
maximizing design we typically apply on these tight jobs
when converting from swing doors to power-operated elevator
doors is to place the new entrance packages outside the
existing hoistway line and into the entrance lobbies.
This also relieves the need for entrance fascia as the edge
of the entrance sill is set just into the line of the
hoistway.
The final results are a functionally new, code compliant,
accessible elevator that will take the facility into its new
generation of use. With the proven components used and
quality installation workmanship, it may even approach the
life span of its original.
Before Alteration
This view of the original machine room shows the ancient
basement winding drum machine. The old mechanical
selector can be seen at the left.
The vintage open relay, city DC, rheostat controller with
its open contactors.
Looking up at the original wood platform and drum safety.
The view of the pit and machine drum. Note the rubber
puck car buffers and lack of a counterweight buffer.
Note the 8 lb./ft. steel counterweight guiderail and 1/2" x
2" bar type support bracket.
See the original babbit bearing overhead sheaves. Note
the roping scheme with 2 ropes from the machine drum to the
car, 2 ropes from the machine drum to the counterweight and
2 ropes between the car and the counterweight. The
original Otis un-switched flyball governor is seen on the
right.
The original lobby entrance at left and the basement
entrance at right are non-ADA swing door type.
After Alteration
The new Hollister-Whitney #44 basement O.D. machine mounted
to an 3/4" adapter plate, which is bolted to the original
Otis machine base. Note, no upthrust value is accorded
to the original Otis base.
This view from the pit shows the new structural anchorage of
the new machine, including anchorage to the existing pit
wall and new pit floor. This anchorage alone is
calculated to hold down the machine, including seismic
reactions.
A view of the new machine's drive & overhead deflector
sheaves with seismic rope retainers.
The new solid state MCE VVVF-AC controller with the solid
state seismic switch mounted to the floor slab to the left
of the controller. The original machine room was used
but cleaned of all foreign utilities and new ventilation and
services added.
The existing overhead sheave room with new Hollister-Whitney
sheaves with seismic rope retainers. Note the original
overhead support sheaves were reused, with the upper level
moved slightly, after structurally proving their strength
per code. The new Hollister-Whitney governor can be
seen behind the sheaves.
The new E/V isolated car sling and platform with
Hollister-Whitney #540 safeties and #379 roller guides.
Also note the repair work to the existing hoistway
fireproofing.
The existing 15 lb/.ft. car guiderails and the 8 lb./ft.
counterweight guiderails and brackets were structurally
calculated to prove them compliant with the most current
elevator code including seismic with respect to deflection
criteria. This picture shows an example of some of the
structural reinforcing that the counterweight brackets
required.
A view of the new sling, car top and GAL door operator.
Note the car is 9'-0" high, more furniture accommodating and
vandal resistant than the standard 8'-0" high car.
The new stainless steel elevator car includes a standard
ADA-compliant car operating panel in the front return.
It also includes an auxiliary COP in the rear wall and a
mirror, as required by San Francisco's Mayor's Office on
Disability Access.
The new two-speed, power operated entrances are 3'-0" wide
by 8'-0" high, providing full width access for wheelchairs.
Note the Smoke Guard drop down smoke curtain fixture over
the entrance.
Drawings & Engineering
Click on the drawing above to open the full drawing set in
PDF format. To see drawings in landscape view, click
on your Adobe Reader's Rotate Counterclockwise image button.
Note drawings cannot be printed or altered. All
drawings and artwork are the property of RCB Elevator
Consulting, LLC and may not be used, copied, or in anyway
used without the owner's consent.
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Essex Hotel