Highway safety in Logan Canyon has been a concern of previous highway
projects, and has been raised in the current project.
Safety for any highway involves two major issues: (i) accident rates
and (ii) severity of accidents. UDOT has provided data for the period 1980-
1985 (6 years) for accident rates in the canyon. These rates were compared
with the accident rate for Rural Arterial Federal Highways in Utah (the standard),
and stattistical analysis indicated 3 or 4 sections of the highway
(of 13 sections) had accident rates significantly higher than those of the
standard. The other sections of the canyon had rates insignificantly differerent
or significantly lower than the standard. Subsequent analysis of the
UDOT rates, however, revealed many were in error, casting serious doubt on
the validity of the data. This also cast doubt on the validity of the standard:
if many of the calculated accident rates for Logan Canyon are wrong,
what about the reliability of the standard, presumably arrived at by the same
methods? Requests for UDOT data upon which these c~lculations are based
were made, but no data has been furnished. In order to make meaningful comparisons
of accident rates, Logan Canyon should be compared with similar canyon
highways, such as Sardine Canyon, Ogden Canyon, Little Cottonwood Canyon,
Provo Canyon and Spanish Fork Canyon. No such comparisons have been made
by UDOT or CH2M, and the necessary data 'has not been provided.
Faced with this serious question concerning accident rates, CH2M chose
instead to compare total accidents over a 6 year period (1980-85) for 0.1
mile sections of the canyon with the average for 0.1 mile sections to determine
the location of the highest accident numbers. This has led to identification
of 16 0.1 mile sections (out of 374 0.1 mile sections total) as having
significantly higher numbers of accidents (4 or more accidents in 6 years,
80% conficdence level) than the average 0.1 mile section. Such results would
occur for any highway, and it is important to note none of these 16 sections
had accident numbers greatly in excess of the expected number. Many sections
of the highway, by the same analysis, have significantly lower numbers of accidents.
At this point, there are no data to support a conclusion that Logan Canyon
has a significantly higher accident rate than any comparable highway in Utah.
With respect to severity of accidents, by far the most common accident is
sliding off the road in Winter, involving only one car. Deaths and serious
injury have been rar~, and the numbers are too low for any valid statistical
analysis. As many deaths have occurred in the lower improved sections (mouth
to Right Fork) as on the ~ of the highway from Right Fork to Beaver Mountain
As the CH2M report concludes, the chances of being involved in a serious
accident in Logan Canyon are small at any time. Safety is not a current issue
in Logan Canyon and, in the absence of valid supporting data, cannot be used
as a justification for major highway modifications.
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