Page 178 - Urban Construction Project Management

Logistics 133
rides close to the face of the building so that the gap at each landing is small. If the
geometry of the installation will not permit this, then a supplemental structure needs to
be built to meet the car. A gate only operable from the outside and one on the structure
side of the hoist are installed so that each opening is safely closed off. A typical person-
nel hoist for construction operates at a speed of about 300+ fpm and by certain local
codes may not exceed 600 fpm.

Other safety considerations that must be observed include the following:
1. A 30-foot safety area should be maintained around the cars. This will include the
installation of safety nets and a sidewalk bridge.
2. A loading dock shed should be constructed that will protect workers and trucks that
will be unloading material at the loading dock.

The hoist location within the plan of the structure is determined by several factors:
1. Good access off the street for the unloading of material from trucks.
2. Close to the center of where material will be used on a floor with clear passage that
will not interfere with critical finishes.
3. Close to the fire standpipe so that firefighters have ready access when they step off
the hoist.
4. Minimal interference with the progress of construction by delaying closing or fin-
ishing critical parts of the building.
5. Avoiding potential conflicts with other activities such as crane picks.
6. Access to remove the hoist from the site after the work is completed.

The number of hoists on a project is determined by a cost benefit analysis considering
the following:
1. Number of workers that need to go up and down the building at peak times.
You want to avoid delays of bringing the workers up to the floors in the morning
and then returning during the lunch break. These delays cause losses of
productivity.
2. The amount of material that will have to be transported during the progress of the
job. In most cases, hoists may be added when the interior work starts for the
structure.
3. The cost of renting the hoist and the cost of the operators.
4. Availability of temporary power.
5. The cost benefit of schedule acceleration brought about by more carrying capacity
versus the possible delaying effect of leave outs at the hoist locations.
6. A rule of thumb is one hoist car for every 250,000 square feet.

A checklist for hoists is shown in Exhibit 6-16.