Climate Change on Winter Weight Premiums and Spring Load Restrictions

Focus Area

Environmental Considerations in Planning








1-2 years

Research Idea Scope

Highway agencies place Winter Weight Premiums (WWP) and
Spring Load Restrictions (SLR) during the winter and spring seasons when the
performance of pavement structure changes due to winter freeze and spring
thaw.  The onset and ending of these
programs in effect are rigid and usually scheduled in advance.  A careful scheduling of WWP and SLR is
required in order to avoid an unnecessary risk of pavement deterioration due to
heavy weight exerted on the pavement. 

Research shows positive trends in winter air temperature
in recent decades, particularly in the lower percentiles of minimum air
temperature.  These trends in winter air
temperature will shift both temporal and spatial extents of regions that are
able to enable WWP and require SLP, and changing winter severity due to climate
change alters the nature and degree of frost penetration in the subgrade, which
subsequently impact the decisions on the onset and ending of WWP and SLR. 

For the trucking, resources, and farming industries,
information regarding the timing of these programs is paramount.  The consequence of being unable to provide
timely and correct information could result in economic losses of the involved
industries as well as expensive repair costs that highway agencies must
face.  While it appears that the
industries and highway agencies have competing goals, there is a working
solution with positive outcomes for both parties.  In addition, the trucking, resources, and
farming industries and their shipping activities are not confined within administrative
boundaries, and thus a standardized procedure is a must between highway
agencies and the industries involved in order for the shipping activities to
take place seamlessly. 

A comprehensive working policy needs to be made as soon
as possible with cooperation with the highway users, involving the trucking,
resources, and farming industries that depend on highways and are affected
through the programs of WWP and SLR. 
Thus, this proposal sets multifaceted goals: (1) to synthesize different
approaches that highway agencies in various regions take for WWP and SLR, (2)
to create a framework to gather information regarding the industries (i.e.,
road users) and their inputs toward the programs, (3) to find vulnerable
regions that climate change would affect the standardized WWP and SLP, (4) to
identify vulnerable routes and possible alternate routes available for the
trucking industry, and (5) to make the findings available to both highway
agencies and users to share the knowledge. 

An in-depth regional analysis of highway agencies’
practices for WWP and SLR has been completed for the Prairie Provinces of
Canada.  A similar analysis for
respective regions of the North America should be carried out, which involves
bidirectional participations of the industries and highway agencies.  Synthesizing information on WWP and SLR will
require reviewing current programs and research activities carried out by
multiple bodies of organizations and agencies, including TRB Committees (AHD65:
Winter Maintenance; AFP50: Seasonal Climatic Effects on Transportation
Infrastructure; and AFB30: Low-Volume Roads), state DOTs, Aurora, Clear Roads,
US Forest Service, US Army Cold Regions Research and Engineering Laboratory,
the Bureau of Land Management, National Oceanic and Atmospheric Administration,
FPInnovations of Canada, and other organizations and agencies in the

Scheduling reliable onset and ending of WWP and SLP
require models that are able to replicate frost penetration and subsequent
thaw, and input data from multiple sources, some of which are from external to
the field of transportation.  In
addition, changing climate is often described by a mean shift as well as a
variance change of climate variables, and the latter is increasing.  The model building process has begun
including the variance in climate data in addition to the mean state
alone.  With variance, in particular, the
current models from the standardized WWP and SLP need to be examined.  Moreover, it is necessary to identify any
availability of alternate routes for a given pair of origin and destination
that would allow more flexible framework of WWP and SLR.  The use of Intelligence Transportation
Systems and Geographic Information Systems helps conduct this complex task,
which requires a large amount of spatial data.

Urgency and Payoff

While extreme weather and conditions are focused when it
comes to the topic of climate change, winter weather conditions can be as
important as or even more important than those extreme conditions, as wintry
weather conditions, such as freezing, drastically change with warming trends of
winter.  Synthesis of current policies
from different highway agencies and concerns from the industries should take
place as soon as possible so that a working overall policy can be drafted
before considerable evidence of climate change manifests itself.

Climate change will bring challenges to both highway
agencies and users who will need to adapt to new conditions that are brought by
changing climate.  Sharing knowledge that
different agencies and users currently possess should become a positive asset
for other agencies and users in different regions that would experience
changing winter conditions.  This should
prevent reinventing WWP and SLP programs in the regions that will experience changing
winter conditions, and both highway agencies and industries will realize
monetary and environmental benefits.


This topic has been modified from its previous submittal
to the 2013 NCHRP Synthesis.  It is
supported by TRB Winter Maintenance Committee, AHD65

Suggested By

Dr. Noriyuki Sato California State University, Chico

[email protected]