Sadly bridges are not immune to accidents.  They happen.  Perhaps the bridge you are researching has been involved in an "incident."  Some famous examples include the:

• collapse of the incomplete Point Quebec cantilever bridge on August 29, 1907, killing 75 workman; and
• destruction of the Tacoma Narrows suspension bridge due to wind gusts.  You should take a look at an MPEG video of the collapse here.

Examples of these and other collapses can be found at http://eduspace.free.fre/bridging_europe/disasters.htm and http://www.iti.northwestern.edu/clear/bridge/bri_dis.html and should definitely be checked out. 

Log Entry #5

Was your bridge ever involved in an accident, no matter how minor? If so, record the details (who, what, when, where) under key question #5 in your research log.