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Agree with Jose. In NY we often see 15-20% trucks (overall) on interstates and on very rural interstate sections, up to 30% or thereabouts. During the night time hours, the values are always much higher than a section's 24 hour average, regardless of urban/rural. Controlled access highways also tend to have higher operating speeds (even in work zones) than non-controlled access highways/arterials and there is generally a direct correlation between operating speed and the likelihood of a fatality. These and other factors need to be taken into account in the determination of whether or not a certain vehicle class is positively correlated with an elevated crash/fatality pattern. To example, years ago, a push was underway to ban freight trucks (Class 5+) from a section of highway during commute hours as there was a perception that they were overtly involved in crashes. I did a manual review of 3 years worth of police accident reports and found that heavy trucks were slightly less crash prone than the rest of the population on this highway section. The real problem vehicle class turned out to be panel vans often used by small businesses. It was suspected that this was because they tend to have poor rear visibility due to a lack of windows and the drivers are as not as stringently licensed as heavy truck drivers are. Those details got lost in the translation of how the police classify vehicles in crash reports and the FHWA style vehicle classes used by surface transportation professionals! Long story short, details matter! I would also recommend the consideration of crashes with injuries too, as they are a harbinger for fatalities. If the person was injured but barely survived or permanently incapacitated, it would still count as "only" an injury. These numbers are also much higher than fatal crashes and provide a more statistically robust population for analysis. Fatalities, on the whole, tend to be a small number and their occurrence may statistically fall into the realm of randomness. (Again, that depends upon the specific details)! Lee Maynus, P.E. Principal Engineer Calmar Telematics, LLC On 9/9/2010 1:40 PM, Jose Holguin-Veras wrote: > 5-6% is typically the percent of trucks in total (day + night) > traffic. At night, and particularly at interstates, it is larger. > > Are the 5-6% figures for total or only for night traffic? My sense is > that this may have an impact on your analysis. > > jhv > > On 9/9/2010 1:21 PM, Dale A Tabat wrote: >> All, >> Both nationally and in the State of Washington, 22 percent of fatalities >> occurring in highway work zones from 2002 to 2009 involved freight >> trucks. >> The average percentage of trucks in Washington State highways is 5-6 >> percent so heavy trucks are over represented in work zone fatalities. >> WSDOT >> and agencies are looking to perform root cause analysis of the >> problem to >> focus potential solutions on elements that most significantly >> contribute to the >> problem. >> >> I am interested in obtaining information related to this research and >> would >> appreciate any work being done or completed. >> >> Are other states doing analysis in this area? >> Are other states interested in this problem? >> >> Thank you, >> Dale A Tabat >> Truck Freight Program and Policy Manager >> Washington State DOT >> [log in to unmask] >> >> >