WRD INFORMATIONAL MEMO NO. 2001.06--Safety--Bridge Measurement Accident
SAFETY--Bridge Measurement Accident
In Reply Refer To:
Technical Operations Program
Mail Stop 405
Sunset Date: July 2002
July 24, 2001
WATER RESOURCES DISCIPLINE INFORMATIONAL MEMORANDUM NO. 2001.06
Subject: SAFETY--Bridge Measurement Accident
This memorandum provides information on a recent accident involving a jet
ski colliding with U.S. Geological Survey (USGS) equipment and recommends
safety procedures to reduce the risk to employees, the general public, and
property. During a recent discharge measurement in the midwest, an
accident occurred when a jet ski struck the current meter suspension cable
that was hanging off a highway bridge. With only the gray 1/4" steel
suspension cable visible to boating traffic, a jet ski operator moving
about at 35 to 40 miles per hour hit the cable. The jet ski operator did
not see the cable until he was directly in front of it and was unable to
avoid a collision, which significantly damaged the jet ski. The impact
released the brake on the sounding reel, caused the line to play out, and
jerked the bridge crane, and resulted in injuries to a USGS employee's arm
and leg. The operator of the damaged jet ski was not injured.
This accident demonstrates the potential for serious injuries to both USGS
employees and the boating public when working on bridges or cableways. To
help avoid this type of accident, please review the safety precautions
found in the "National Field Manual for the Collection of Water Quality
Data - Chapter A9.4.2 Safety in Field Activities," reprinted below for
your information. Also included are examples of two effective
suspension-cable safety markers.
SAFETY IN FIELD ACTIVITIES
A.9.4.2 WORKING ON BRIDGES
a) A bridge safety plan is required by WRD Memorandum No. 95.17. For
every bridge site, develop and diagram a detailed procedure that conforms
to State and Federal regulations. Keep this procedure and diagram in the
field folder. The bridge procedure includes plans for safety cones and
signs, lane blockage, and traffic control.
b) Equipment used for sampling from a bridge can be heavy and unwieldy.
Practice assembling and using the equipment before starting field
activities, and make sure the equipment is operational before leaving the
office. When using a bridge crane, keep a pair of heavy-duty wire cutters
readily available for cutting the cable in case debris snags the sounding
line. (Note: WRD Memorandum No. 99.01 requires use of breakaway sounding
reel cable kits where appropriate.)
c) Be aware of boat traffic. The bridge crane cable should have strips of
bright plastic flagging attached in intervals to make it easily visible to
all boat traffic. (Note: please see examples listed below for other
methods. Also, some scenarios, such as large bridges or heavy boat
traffic, may require an additional person to be stationed on the opposite
side of the bridge to warn the streamgager of oncoming water traffic.)
d) A PFD must be worn when working on bridges. The suspender type PFD is
approved for bridgework.
e) Workers involved in peripheral activities should wear high-visibility
vests with reflective tape.
SUSPENSION-CABLE SAFETY MARKERS EXAMPLES
Two other examples of methods for marking cables are:
One inexpensive and highly visible marker used to warn boating traffic of
the current meter or water sampler-suspension cable has been designed by
Fred Morris (Mississippi District Safety Officer). The Hydrologic
Instrumentation Facility has a Technical Information Sheet describing this
"Suspension-Cable Safety Marker" on its website at
http://wwwhif.er.usgs.gov/uo/. (Click on "Publications" and then on
"Technical Information Sheets," and then on "Fabricating a
Suspension-Cable Safety Marker"). The marker consists of a 6 to 8 foot
length of 1-1/2-inch diameter PVC pipe covered with high-visibility
reflective and glow-in-the-dark tape, suspended by a rope side-by-side
with the current meter or sampling equipment. The Technical Information
Sheet will provide a parts list, sources of supply, and directions for
fabricating the marker, and a paragraph or two on its use and maintenance.
Another warning method, reported by Greg Susich (Eureka Satellite Office,
California) uses an orange road cone (2 foot size) and 3-pound weight.
The rope is threaded through top of road cone until 3 feet of rope has
past the bottom of cone. The rope is tied 3 feet from end with an old
nut-cable clip or group of knots or any plug that will act as a stopper to
prevent the cone from sliding down the rope. The weight is attached to
end of rope. The marker is lowered from bridge until the weight is under
water and the cone is kept above water surface. With the weight in water,
the cone will automatically be pulled downstream away from sampling
equipment and not swing back and forth. The top end of rope can be
attached to the bridge crane or moved by hand with each section throughout
measurement. The cone is very visible to boats from good distance and is
rarely approached by boat operators because they believe the cone marks a
submerged obstacle to be avoided.
A small battery powered strobe light, similar to those used on PFD's, can
also be attached to the above examples for further visibility.
District Offices have no doubt used other methods and devices for warning
boaters of suspended cables. What is important is that we recognize the
potential hazard to boaters, and that we employ effective warning
measures.
If you have any questions, please contact your Regional Safety Officer.
/signed/
Stephen F.
Blanchard
Acting Chief,
Office of Information
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Steve Blanchard
Acting Chief, Office of Information
U.S. Geological Survey Phone: 703-648-5629
440 National Center Fax:
703-648-5644
Reston, VA 20192
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