15 August 2002
Roadway. Where an entrance caisson is to be used as a roadway for
vehicular traffic, the dock coping in the way of the caisson shall be designed and
detailed to suit.
Cross Section. The most important influence of the inside as well as the
outside shape of a drydock cross section is the structural type (and construction
methods) adopted. For relation of shape to these factors, see Figure 3-3.
Floor and Wall Coping Elevation. Design the coping of the drydock wall
high enough so that it will not be overtopped by severe waves which could possibly
occur at high water, or at the grade of the surrounding yard, whichever is higher.
Establish floor elevation as set forth in sections 3-1 through 3-3; normally floors shall be
level in both directions.
Service Tunnels and Galleries
Piping. Provide service tunnels in and near the top of walls for piping,
with galleries from these openings into the drydock chamber. Service tunnels and
galleries should be designed and constructed such that they are kept dry at all times.
Sump pumps and isolation valves should be installed if necessary. Tunnels should be
wide enough to accommodate all of the required piping plus clearance for people to
walk and to effect repairs. The height should provide 1.98 m (6 ft 6 in) headroom even
where pipe crossovers exist. Refer to section 3-4.3.5 for the relation of shape and
location of tunnels to crane tracks.
Electric Lines. On small docks, electric lines are placed in ducts encased
in concrete on the land side of the walls. For large docks, where the electrical
requirements are great, place lines in a separate concrete electrical tunnel on the land
Steps or Altars. The number of setbacks or altar platforms in the inboard
faces of the dock walls shall be kept to a minimum.
Single Stepback. For gravity walls, a single stepback may be made, part
way up on the inboard face, to reduce concrete thickness in the upper part of the wall
and to improve the stability of the wall.
Low Step at Base of Wall. In some instances, a low step may be
provided at the base of the wall to facilitate drainage system details. This step is not
objectionable if it is not too wide, and will result in economy by reducing the effective
height of the wall.