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        


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. 


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. 


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 

If you have any questions, please contact your Regional Safety Officer. 


                                                        Stephen F. 
                                                        Acting Chief, 
Office of Information 

Steve Blanchard                                        
Acting Chief,  Office of Information        
U.S. Geological Survey                          Phone: 703-648-5629
440 National Center                                  Fax:      
Reston, VA  20192