Newsletters and Summaries

The Southern Plains Transportation Center compiles periodic newsletters to communicate the impact of the center in the areas of research, outreach, workforce development and more.

A weather and climate trends roadmap for oklahoma 

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OVERVIEW: Oklahoma is used to extreme weather - from heatwaves and droughts, to severe storms, ice and snow, and floods. The state’s large transportation network is regularly exposed to adverse conditions, which contribute to degradation, damage, and disruption. Nationally, transportation agencies are becoming increasingly aware of the longer-term risks to
infrastructure posed by changing environmental conditions. However, adaptation and mitigation of hazards on regional and local scales can be limited, in part due to a lack of regionally relevant information on trends. We developed a comprehensive climatological analysis using multiple data sources to project trends in temperature and precipitation extremes through the
21st century. Expert input from transportation professionals identified applicable metrics and thresholds. This work suggests that Oklahoma is likely to experience: (1) A decrease in winter weather hazards such as extreme cold, freeze thaw cycles, and winter precipitation. Freeze-thaw days decline by 15-30% by 2050, and the frequency of snow and ice by 30-40%; (2) An increase in hazards such as heatwaves, drought, and heavy precipitation. Hot summers analogous to 2011 in the state could occur every few years by the late 21st century (2061-90). Extreme precipitation, such as the 100-year daily rainfall, also increases, even by mid-century, on average becoming the 10-20 year rainfall. Some of the largest uncertainties in the trend are dictated by the degree of possible climate change, based on fossil fuel emissions. An unabated increase in greenhouse gas emissions produces more pronounced increases in heat and decreases in cold weather-related hazards, especially later in
the century. These underlying changes in the probability of hazards suggest that some physical infrastructure may not be prepared to withstand future extremes without adaptation.

ANALYSIS: 

newslet.JPG
  • The flow chart shows the
    activities associated with this
    research
  • Details on each stage of the
    work can be found in the SPTC final report –
    SPTC14.1-50 (McPherson/Mullens)
  • Work in collaboration with the South
    Central Climate Science Center to aid the SPTC
    research focus on climate resilient transportation
    ttp://southcentralclimate.org

CLIMATE TRENDS: 


20-30% fewer freeze-thaw cycles by 2050, 30-60% by 2090.
The coldest nighttime temperatures warm 5-10 degrees F by late
century. Implication: Little short-term benefit, longer-term
reduction in damage and maintenance costs due to freezethaw
damage.

Climate Trends .jpg

25-40% decrease in ice/snow frequency by 2050, 40-80% by
2090. Intensity of individual events on average does not
change, Central Oklahoma winter temperature climatology
similar to Dallas by 2090 with high emissions. Implication: Still high variability in winter storms, but lower frequencies
may eventually decrease maintenance and operation
costs/activities. Less winter-related disruption.

Mcpherson pic.jpg

Frequency of 100 degrees F days increases by a factor of 2-3 by
2050, and 4-6 by 2090. Summers like 2011 occur on average every 6 years by 2090 with mid-range emissions, and every 2 years with high emissions. Peak summer temperatures could reach or exceed 120 degrees F. Implication: multi-decade fixed infrastructure vulnerable to shortened lifespan; changes in
maintenance schedules; possible adaptation of bridge superstructures, road surface materials (e.g., asphalt binders)

Most models project an increase in extreme daily extreme
precipitation at 2-100 year return periods. Magnitude
changes are highly dependent on each model and are
uncertain. On average, the historical 100-year rainfall occurs
every 15-20 years by 2050 and 11-18 years by 2090.
Implication: Non-stationary precipitation trends will affect
hydrologic design for roads, bridges, and culverts. Increased
flooding damage through scour and erosion.

Moderate or greater drought becomes about 2-3 times as frequent by 2090. Implications: As well as impacting the regional economy (e.g., agriculture, energy, water), drought and low soil moisture promotes cracking and
shrinkage, and with some soil types this movement can damage surface infrastructure. Embankment and slope stability issues when coupled with more variable and intense precipitation events and enhanced wet/dry cycles.

RESOURCES: State climate futures summaries are being developed for each SPTC region state, and include detailed information for each trend. Oklahoma and Texas have an expected release in September 2017. For other resources on how to incorporate climate futures in transportation design and planning, the Federal Highways Administration has case studies, best practices and reports on their website:  https://www.fhwa.dot.gov/environment/sustainability/resilience/. We hope to
make many of the datasets and graphical summaries generated from this work available to use. Please contact Esther Mullens (esther.white@ou.edu) for more information.

ABOUT THIS SUMMARY: Historical information alone no longer captures the range of potential weather and
climate extremes that may be experienced in the future in Oklahoma, with broad implications for the transportation
sector. The Final Report referenced in this summary is available upon request. Please send inquiries to sptc@ou.edu.


Bridge Timber Pile Treatment, repair and assessment techniques

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OVERVIEW: Oklahoma is rated first in the Nation in the percentage of bridges that are structurally deficient or functionally obsolete (OkTC 2013).  According to Federal Highway Administration data, Oklahoma has approximately 23,250 bridges maintained by state, County, City, and Tribal governments.  The Oklahoma Department of Transportation estimated that it would cost $3.4 billion to replace these bridges (OkTC 2013).  As funds for replacing bridges decline and construction costs increase, effective rehabilitation and strengthening techniques for extending the life of the timber substructures in bridges with structurally sound superstructures has become even more important (Iowa 2012). These techniques can facilitate county, tribal, and local government officials in prioritizing and wisely spending bridge and road maintenance resources. Implementation can also result in successfully extending the life of bridges and enhancing stewardship and safety (OkTC 2013).

CURRENT TECHNIQUES: There are a number of timber pile treatment, repair and assessment techniques being used across the country today (Iowa 2012). Preservative treatments are generally oil-borne or water-borne preservatives and are applied to timber to enhance its longevity or service life and will depend upon a range of factors including type of preservative, treatment quality, construction practices, type of exposure, and climate (Iowa 2012). Copper naphthenate, either in liquid or paste form, is the most commonly used preservative treatment indicated in a national survey (Iowa 2012). The American Wood Protection Association (AWPA) has produced standards for treatment and care of timber products for use in bridge applications.

Available repair methods for timber piles can be categorized by the stage of biological or physical deterioration in which they are best applied: preventive maintenance, remedial maintenance and major maintenance (Iowa 2012). Preventive maintenance is applied when no deterioration is observed, but conditions are favorable for decay. This type of maintenance is associated with the best cost savings over the long term because it reduces the greater costs of major rehabilitation due to maintenance deferment (Iowa 2012). Techniques include moisture control, in-place treatments (e.g. surface treatments, paste, fumigants) and minor crack repair (e.g. epoxy grouting) (Iowa 2012).

Remedial maintenance is used when non-structural deterioration is observed. It serves to protect the strength and environmental resilience of piles. It does this by repairing the pile and inhibiting the exponentially-increasing decay and includes the following techniques (Iowa 2012):

  • Posting/splicing – removing and replacing the damaged portion of timber at or above-ground level (OkTC 2013)
    • connecting the new portion via concrete jacket or fishplates (shown right; White et al. 2007)
    • connecting the new portion via fiber reinforced polymers (FRP) sheets or composites
    • mechanical splicing – lap splices secured with metal screws
    • posting and epoxy grouting procedure
  • Concrete jacketing – encasing pile with reinforced concrete or concrete-filled corrugated pipe
  • Polyvinyl Chloride (PVC) Wrap - flexible plastic wrap tightly drawn/attached to pile
  • Epoxy-Injected Piles (OkTC 2013),
  • Installing steel H-pile sections or mild-steel reinforcement (e.g. angles, channels, W shapes), and
  • FRP composite shell - FRP jacket, an underwater epoxy or grout fill, or carbon fiber reinforcement between the FRP jacket and the timber pile (shown below; SPTC 2017, Lopez-Anido et al. 2005).

Design tables and installation procedures of splice repair have been developed by an Oklahoma study to assist county management in choosing a replacement shape that will safely take the load from the bridge deck to the old pile underground (OkTC 2013). The final design specifies the details in all welds, including types of weld and sizes of weld.  The guidance also includes details of splice connections.  Diagrams are provided to assist in the installation process (shown right). These types of repairs can adequately restore strength and stiffness and transfer loads from the super structure to the foundation. 

Major maintenance, which is considered to be the most costly type of maintenance due to the extent of damage, is applied to correct and restore the strength of the pile structure and includes adding supplemental piles for support.

Studies also noted techniques for assessing timber pile condition, which include visual assessment, probing and picking, moisture measurement, sounding, stress wave devices, drill resistance devices, core boring and preservative retention analysis. However, any single method may give an incomplete or inaccurate assessment of the given substructure element; therefore, using multiple assessment methods to evaluate a given structure is recommended (Iowa 2012).

ABOUT THIS SUMMARY Implementation of effective timber pile treatment, repair and assessment techniques can support the protection and strengthening of structures and extend their life expectancy, enhance user safety and reduce costs. The Final Reports referenced throughout this summary are available upon request.  Please send inquiries to sptc@ou.edu.

The Southern Plains Transportation Center is a consortium of eight universities in U.S. Department of Transportation Region VI: the University of Oklahoma, Oklahoma State University, Langston University, University of Arkansas, University of New Mexico, Louisiana Tech University, University of Texas at El Paso and Texas Tech University.

The SPTC provides a unique opportunity through multi-institutional initiatives to develop comprehensive, cost-effective, and implementable solutions to critical infrastructure issues facing the transportation systems of the region and the nation, and to prepare transportation professionals for leadership roles through Research, Leadership, Collaboration, Education, Outreach, Tech Transfer and Workforce Development activities.

 

Newsletter Archive

Fall 2016 newsletter - 
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Spring 2015 newsletter - Download PDF

Fall 2014 newsletter - 
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Other Publications  

University Transportation Center Program, Design of Integral Abutment Bridges for Extreme Climates - September 2015

OU School of Civil Engineering and Environmental Science, Communique - Summer 2014 (see pg. 14)