also sent to several U.S. Department of Agricul-
restrictions did not significantly reduce road main-
ture Forest Service (USFS) offices (as the USFS
tenance also indicated that it might be correlated
maintains approximately 360,000 miles of low
to a lack of strict enforcement. One case was cited
volume roads), and to selected report companies.
in which, even when restrictions are posted, trucks
The remainder of this report discusses survey
are occasionally allowed to haul through the night
results.
from approximately midnight until 5:00 a.m., dur-
Thirty-six state DOTs and three USFS Regional
ing which time the roads stiffen because of night-
Offices responded to the survey. Figure 2 shows
time freezing. This practice was allowed for log-
the states in which DOTs post springtime load
ging operations so as to minimize the adverse
restrictions. Regions north of the white line are cat-
economic impact (to the timber company) of a
egorized as areas of seasonal freezing based on
complete prohibition on hauling. Researchers in
either 0.3 m (1 ft) of frost penetration in 10 years
another state are developing a quantitative tech-
or an average temperature of 0C (32F) during
nique for indicating when frozen roads will not
one month in 10 years. Although some states north
be damaged. This could partially counteract the
of the white line in Figure 2 appear to have no
negative effect of spring haul restrictions on local
load restrictions, roads may be posted by agen-
economies.
cies other than state DOTs, such as counties, cit-
Sixteen state DOTs indicate that they post load
ies, towns, the USFS, and private organizations.
restrictions annually, and four states post their
All but two of the states that post load restrictions
roads at least occasionally or when conditions
indicated that restrictions are enforced, and they
warrant. All of the states posting restrictions do
are most commonly enforced (with the penalty of
so on asphalt-surfaced roads, 12 on chip-sealed
a fine) by the state police/highway patrol. Inter-
roads, and only five on gravel-surfaced (or
estingly enough, the only state that indicated
unsurfaced) roads. Unsurfaced and gravel-
DOT Imposes Seasonal Load Restriction
DOT Does Not Impose Seasonal Load Restriction
Information Not Available, Did Not Respond To Survey
Seasonal Frost Line
Figure 2. States in which DOTs post seasonal load restrictions. Seasonal frost
line is based on 0.3 m (1 ft) frost penetration in 10 years or an average of 0C
(32F) during one month in 10 years.
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