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    <title>Research in Progress (RIP)</title>
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    <atom:link href="https://rip.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Research in Progress (RIP)</title>
      <url>https://rip.trb.org/Images/PageHeader-wTitle-RIP.jpg</url>
      <link>https://rip.trb.org/</link>
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    <item>
      <title>Influence of Traffic Noise and Light on Wildlife Movement Near Highways</title>
      <link>https://rip.trb.org/View/2691660</link>
      <description><![CDATA[Traffic results in noise and light propagated from roadways into surrounding landscapes, including human and natural communities. A previous National Center for Sustainable Transportation (NCST) project has supported the development of multi-scale (local to state) models of traffic illumination and noise extending from highways. These traffic-effect areas may be habitat for a wide range of species, including wildlife attempting to cross highways via existing culverts and bridges, or purpose-built wildlife crossings. With previous NCST research using camera traps, researchers found that coyote and mule deer have varying behavioral responses to traffic noise at wildlife crossings. This project extends both the noise and light modeling and the previous investigations of wildlife crossings to include more species (mountain lion, mule deer, and Peninsular bighorn sheep) and many more highways and regions. The research team will statistically model the effect of traffic noise and light from traffic on occurrence of these 3 species and movements of global positioning system (GPS)-collared individuals as they approach highways. This information is critical in informing and making more effective the massive investments that local, state, and federal governments are making in wildlife crossings and fencing to improve driver and wildlife safety. In other words, knowing the traffic effects on wildlife as they approach highways will allow mitigation of those effects using design and construction of the crossings, such as barriers and berms. Because wildlife crossings are the primary investments transportation agencies make to reduce wildlife impacts and increase driver safety, understanding wildlife ability to get to these crossings and use them is critical to the effectiveness of the investment and the role the investment plats in environmental sustainability.]]></description>
      <pubDate>Sun, 12 Apr 2026 23:12:49 GMT</pubDate>
      <guid>https://rip.trb.org/View/2691660</guid>
    </item>
    <item>
      <title>Evaluating the I-25 Greenland Wildlife Overpass using network camera monitoring</title>
      <link>https://rip.trb.org/View/2643441</link>
      <description><![CDATA[This project will examine the effectiveness the largest wildlife overpasses in the U.S. and will explore the application of cameras with networked and high-quality imaging and other other methodologies. The study should inform future wildlife mitigation design decisions and advance the ability to study and monitor wildlife structures with increased safety and accuracy and reduced staff time and cost.]]></description>
      <pubDate>Tue, 23 Dec 2025 13:59:51 GMT</pubDate>
      <guid>https://rip.trb.org/View/2643441</guid>
    </item>
    <item>
      <title>Automated Wildlife Detection for Wildlife Vehicle Collision Reduction</title>
      <link>https://rip.trb.org/View/2593929</link>
      <description><![CDATA[Large mammals cross highways to access core habitat areas, presenting significant safety hazards for Oregon drivers. Transportation infrastructure can in turn present significant disruption for wildlife connectivity. Automated wildlife detection systems tailored for Oregon conditions could enable Oregon Department of Transportation (ODOT) to efficiently assess the performance of constructed wildlife passage features, validate predicted wildlife crossing locations, monitor changes in the timing and location of crossing patterns as the climate and populations change, provide cost-effective detection systems for the many areas where crossing structures are not feasible, and most importantly reduce wildlife vehicle collisions.]]></description>
      <pubDate>Thu, 28 Aug 2025 11:42:32 GMT</pubDate>
      <guid>https://rip.trb.org/View/2593929</guid>
    </item>
    <item>
      <title>Vehicle Collision Mitigation Phase II - Determining Effectiveness of Wildlife-Vehicle Collision Mitigation Projects Phase II</title>
      <link>https://rip.trb.org/View/2582853</link>
      <description><![CDATA[The research is aimed at estimating passage rates or relative use of crossing structures for large mammals and identify other wildlife species using crossings at constructed and planned wildlife-vehicle collision mitigation projects for a 2-3 year period. In instances where fencing will be constructed during the study, the research team will compare use of crossing structures over time to evaluate the effectiveness of the fencing.
The specific objectives of this study are to: Compare wildlife passage rates or relative use of crossings with studies done in other western states; Identify infrastructure shortcomings or other factors that contribute to low passage rates or low relative use rates; Collate and review wildlife-vehicle collision and carcass collection data to determine the effectiveness of constructed projects in reducing wildlife-vehicle collisions, or at least document baseline wildlife-vehicle collision rates for planned projects; Create a guide for designing effective wildlife crossings and for improving existing drainage structures for mule deer (Odocoileus hemionus), elk (Cervus elaphus), black bear (Ursus americanus) and Mountain lion (Puma concolor).]]></description>
      <pubDate>Mon, 04 Aug 2025 17:51:43 GMT</pubDate>
      <guid>https://rip.trb.org/View/2582853</guid>
    </item>
    <item>
      <title>Practices for Wildlife Passage and Habitat Connectivity





</title>
      <link>https://rip.trb.org/View/2558417</link>
      <description><![CDATA[State departments of transportation (DOTs) install wildlife crossing structures and enhance existing structures to provide safe passage for wildlife across roadways. These passages provide safety benefits to motorists by reducing collisions. Other benefits include connecting fragmented wildlife habitats, minimizing property damage and associated costs, and increased safety of maintenance workers by reducing exposure to animal carcasses. 

The Federal Highway Administration (FHWA) guidebook Wildlife Crossing Structure Handbook Design and Evaluation in North America (2011) is one of several resources available to practitioners. However, research and implementation work since its publication provide new insights that could inform the planning and design for future wildlife crossings. Research is needed to consolidate existing resources and guidance to support state DOTs in identifying effective practices for future designs. 

OBJECTIVE: The objective of this research is to develop a guide that documents effective practices for wildlife passage and habitat connectivity. At a minimum, the guide shall: Be designed to benefit a multidisciplinary range of transportation practitioners responsible for wildlife permeability planning, project initiation, design, construction, maintenance, and monitoring; and Consider a range of scenarios including target species considerations, site variables, and distinguishing between purpose-built versus existing retrofit, with the goal of presenting effective practices.

]]></description>
      <pubDate>Tue, 27 May 2025 20:26:05 GMT</pubDate>
      <guid>https://rip.trb.org/View/2558417</guid>
    </item>
    <item>
      <title>Identification and prioritization of road sections with a relatively high concentration of large wild mammal-vehicle collisions in Gallatin County, Montana, USA</title>
      <link>https://rip.trb.org/View/2437173</link>
      <description><![CDATA[The primary objective of this project is to identify and prioritize the road sections in Gallatin County that have a relatively high concentration of collisions involving large wild mammals. These road sections may then later be evaluated for potential future mitigation measures aimed at 1. Reducing collisions with large wild mammals, and 2. Providing safe passage across roads for large wild mammals, as well as other wildlife species in the area. We acquired the 3 datasets related to large wild mammal-vehicle collisions in Gallatin County: 1. Wildlife-vehicle crash data collected by law enforcement personnel, 2. Carcass removal data collected by road maintenance personnel; and 3. Grizzly bear road mortality data by the U.S. Geological Survey. The carcass removal data and grizzly bear road mortality data were merged into one carcass database. We conducted separate analyses for the crash data and the carcass data. We conducted two different types of analyses to identify and prioritize road sections with the highest number of wildlife-vehicle crashes and carcasses: 1. Kernel Density Estimation (KDE) analysis that identifies road sections with the highest concentration of collisions, and 2. Getis-Ord Gi* analysis identifies road sections that have statistically significant spatial clusters of collisions. There was great similarity between the hotspots identified through the Kernel Density Estimation analyses for 2008-2022 and 2018-2022 for both the crash and carcass removal data. The same was true for the Getis-Ord Gi* analyses. Especially sections of I-90 and US Hwy 191 between I-90 through Four Corners to the mouth of Gallatin Canyon had the highest concentration of wild animal crashes and large wild animal carcasses. Based on the Getis-Ord Gi* analyses, these road sections generally had concentrations of crashes and carcasses that were significantly higher than expected should the crashes and carcasses have been randomly distributed. In other words, these road sections do not only have the highest concentration of crashes and carcasses, but the identification of these road sections is not based on coincidence. These road sections have a concentration of crashes and carcasses that is beyond random.]]></description>
      <pubDate>Mon, 30 Sep 2024 13:38:34 GMT</pubDate>
      <guid>https://rip.trb.org/View/2437173</guid>
    </item>
    <item>
      <title>Modeling Traffic Noise and Light on Natural Landscapes at the State Scale</title>
      <link>https://rip.trb.org/View/2431331</link>
      <description><![CDATA[Anthropogenic noise and light have been shown to impact wildlife behavior, distribution, movement, and population fitness and survival. Traffic noise and light can inhibit wildlife use of areas adjacent to roads, impair wildlife perception of traffic risks, and cause a barrier effect to wildlife occurrence and movement well beyond road edges. A critical action being taken by states to repair wildlife movement across roadways is construction of wildlife crossings, theoretically providing a safe passage across roads. Planning the location of these crossings and to some degree their design currently does not take into account traffic noise and light impacts on wildlife approaching the structures. The researchers will develop a method for statewide modeling of noise and light intrusion into areas adjacent to roads to aid locating and designing crossings to maximize wildlife approach and use. These models would have the added benefit of estimating traffic impacts as part of environmental analysis associated with delivering transportation projects. The researchers will use the Federal Highway Administration (FHWA) Traffic Noise Model (TNM) and light-scale tools in the geographic information systems (GIS) software ArcGIS to model the “noise-scape” and “light-scape” at high-resolution around California (CA) state highways and I-5 in Oregon (OR) and Washington (WA). The researchers will use 1/10 mile post-miles as the sources of traffic noise and light and model propagation of both across adjacent landscapes out to at least 1 kilometer. The researchers will validate the models in the field using transects of noise and light measurements. The outputs will be digital (raster) maps that show the high and low impact areas. The researchers will share these data through a data portal being supported through a separate grant from the Wildlife Conservation Network. Although the focus is on wildlife impacts, there would be secondary benefits for planners in communities. The researchers will share the method developed through publications and conference presentations.]]></description>
      <pubDate>Tue, 17 Sep 2024 16:18:13 GMT</pubDate>
      <guid>https://rip.trb.org/View/2431331</guid>
    </item>
    <item>
      <title>Assessment of Aquatic Organism Passage Through 3-Sided and 4-Sided Culverts on High Quality Streams  
</title>
      <link>https://rip.trb.org/View/2427732</link>
      <description><![CDATA[When culverts are placed into streams, it is important to ensure that the culvert does not inhibit aquatic organism passage (AOP). AOP refers to the capacity of a structure to maintain the natural continuity of the habitat, stream flow velocities, and depth so that aquatic organisms (e.g., fish, macroinvertebrates, salamanders, etc.) can move through the structure, both up and down stream, uninhibited. This research study is important for both Ohio Environmental Protection Agency (OEPA) and the Army Corps of Engineers (ACE) standards as well as Ohio Department of Transportation (ODOT) best practices. To ensure the most appropriate structures are utilized in high quality streams that support the viability of aquatic life, research is needed to determine the actual impact of these structures and their support of the passage of natural organisms in streams. The goal of this research is to determine the impact to AOP of 3- and 4-sided box culverts in high quality streams in Ohio and provide recommendations for the best applications based on stream characteristics. The objectives of this research include the following: (1) evaluate AOP for vertebrates and macroinvertebrates in 3- and 4-sided box culverts on high quality streams; (2) evaluate barriers to AOP by culvert type; (3) identify limitations of each culvert type, considering natural features, such as, but not limited to landscape and geology; (4) provide data set(s) demonstrating viability of AOP in culverts (or not) based on a variety of factors, such as, but not limited to slope, culvert type, velocity, etc.; and (5) recommendations for practices to improve the viability of AOP in culverts, such as, the use of products designed to support AOP, burying inverts in 4-sided structures, etc. ]]></description>
      <pubDate>Fri, 13 Sep 2024 11:19:21 GMT</pubDate>
      <guid>https://rip.trb.org/View/2427732</guid>
    </item>
    <item>
      <title>Assessment of Wildlife-Road Conflicts for Protected Species</title>
      <link>https://rip.trb.org/View/2422609</link>
      <description><![CDATA[Roads pose several risks to wildlife due to sources including direct mortality from vehicle
collisions, fragmentation of key habitat, and barriers to movement that result in isolated
populations. For imperiled species, such threats can have an outsize impact on species
persistence. Mitigation efforts such as wildlife crossings, fencing, roadside vegetation
management, and retrofitting roads with wildlife-friendly design features have been shown to be effective at reducing the negative impacts of roads on wildlife. A project is proposed, to identify priority sites in Iowa where road mitigation can provide the largest benefit to Species of Greatest Conservation Need (SGCN). Ongoing work developing habitat suitability models will be built on for a suite of SGCN to predict statewide species’ relative occurrence statewide and calculate an index of expected biodiversity. Geospatial data on road configuration, traffic intensity, and wildlife mortalities will be used to quantify road risk to identify sites with the highest combined biodiversity scores and road risk. Field surveys will be conducted at these sites to ground-truth model predictions, provide empirical estimates of species richness and density, and evaluate the feasibility and expected benefits of different mitigation efforts. Project deliverables will include: (1) recommendations for road mitigations at 10 sites identified to be SGCN hotspots and (2) a web-based application for users to explore predicted hotspot maps and prioritize future sites for mitigation. This project will help the Iowa Department of Transportation (DOT) reduce negative impacts of roads, support conservation of Iowa’s wildlife, and provide a framework for prioritizing mitigation efforts that can serve as a model for other states in the Midwest.]]></description>
      <pubDate>Tue, 27 Aug 2024 12:29:06 GMT</pubDate>
      <guid>https://rip.trb.org/View/2422609</guid>
    </item>
    <item>
      <title>Concrete Box Culvert (CBC) Adaptation to Increase Ungulate Use 
</title>
      <link>https://rip.trb.org/View/2417305</link>
      <description><![CDATA[This empirical study will explore the impact of color on the effectiveness of box culvert use by ungulates to cross beneath highways. Ungulates are deterred more by bright colors than by, for example, blue. If concrete box culverts (CBCs) can be made more effective for ungulate crossings, their use can lower the occurrence of wildlife-vehicle collisions and reduce the resulting harm to people and property, as well as to the wildlife.]]></description>
      <pubDate>Wed, 14 Aug 2024 12:10:15 GMT</pubDate>
      <guid>https://rip.trb.org/View/2417305</guid>
    </item>
    <item>
      <title>SH 13 Wildlife Mitigation Measures</title>
      <link>https://rip.trb.org/View/2417290</link>
      <description><![CDATA[This State Highway 13 Wildlife Mitigation Measures Research Study evaluates the effectiveness of wildlife mitigation measures installed in the Colorado Department of Transportation (CDOT)’s SH 13 Fortification Creek Improvement Project. The main objective is to determine the effectiveness of the wildlife mitigation features’ influence on wildlife-vehicle collisions (WVCs). The five-mile project includes the following wildlife mitigation measures: a radar wildlife detection and driver alert system, four low (4 feet) fence sections, one with a wildlife detection driver warning system; three high (8 feet) fence sections, one with a wildlife crossing structure underpass; 11 dual sided escape ramps; and two electrified ZapCrete (TM) wildlife deterrent mats at intersections.]]></description>
      <pubDate>Tue, 13 Aug 2024 17:44:08 GMT</pubDate>
      <guid>https://rip.trb.org/View/2417290</guid>
    </item>
    <item>
      <title>I-25 Gap Project Wildlife Structures </title>
      <link>https://rip.trb.org/View/2417289</link>
      <description><![CDATA[The I-25 South Gap Wildlife Mitigation Study is evaluating the effectiveness of a wildlife mitigation system constructed as part of a highway widening project on I-25 between Castle Rock and Monument. The mitigation system includes four underpasses, a major bridge replacement, small mammal connectivity features, wildlife exclusion fencing and fence end treatments, escape ramps, and wildlife guards.

Mitigation effectiveness is being measured using two general pre- and post- construction measures: the change in wildlife-vehicle collisions as measured by crash and carcass counts, and the numbers of each species using the wildlife crossings and their passage rates. The effectiveness of the other mitigation features is measured via breach and repel rates at wildlife guards or fence end treatments, and intercept and escape rates at escape ramps. These measures will be quantified relative to pre-established performance measures to assess the overall effectiveness of the mitigation and each of its component parts.

This research will provide insight into the value of the mitigation investments on I-25; determine whether adjustments to any of the mitigation components may be warranted to improve the effectiveness of the mitigation; and address gaps in the understanding of biologically and cost-effective mitigation designs for major infrastructure projects. The study findings are expected to inform the design of future mitigation projects in Colorado, western North America, and beyond.]]></description>
      <pubDate>Tue, 13 Aug 2024 17:38:50 GMT</pubDate>
      <guid>https://rip.trb.org/View/2417289</guid>
    </item>
    <item>
      <title>US 160/SH151 Wildlife Mitigation Research</title>
      <link>https://rip.trb.org/View/2417257</link>
      <description><![CDATA[The Colorado Department of Transportation (CDOT) and partners Colorado Parks and Wildlife (CPW) and the Southern Ute Indian Tribe (SUIT) along with non-government organizations invested in wildlife mitigation features along US 160 and SH 151 in the Chimney Rock area. The 1.5 miles of wildlife exclusion fence (MP 126.4 to 127.9) was erected in 2022 to guide wildlife to a new wildlife overpass, Mile Post (MP)127.2, and underpass, MP 126.8. The mitigation also included a wildlife deterrent double cattle guard (deer guard) at the junction of SR 151, multiple escape ramps, and fence end in-ground erosion control netting to deter wildlife fence end runs into the fenced area. ]]></description>
      <pubDate>Tue, 13 Aug 2024 15:48:34 GMT</pubDate>
      <guid>https://rip.trb.org/View/2417257</guid>
    </item>
    <item>
      <title>SPR-4922: Identify Bridge Design Guidelines for Wildlife Crossings</title>
      <link>https://rip.trb.org/View/2410438</link>
      <description><![CDATA[When the Indiana Department of Transportation (INDOT) is designing a new or replacement bridge, the information needed for wildlife crossings from the Indiana Department of Natural Resources (DNR) is needed in the design process. This project will make detailed requirements for wildlife crossings from DNR available to INDOT earlier in the design process to avoid spending time and money on redesigns.]]></description>
      <pubDate>Tue, 30 Jul 2024 11:12:44 GMT</pubDate>
      <guid>https://rip.trb.org/View/2410438</guid>
    </item>
    <item>
      <title>Synthesis of Information Related to Highway Practices. Topic 55-18. Permitting, Design, and Construction Practices for Aquatic Organism Passage</title>
      <link>https://rip.trb.org/View/2209731</link>
      <description><![CDATA[State departments of transportation (DOTs) have traditionally designed structures to convey water under roads based on cost, hydraulic efficiency, and risk criteria. However, this design approach can result in barriers to aquatic organism passage (AOP) as an unintended and undesired consequence. Thus, state DOTs have come under increasing regulatory direction to ensure AOP through structures.
State DOTs on the West Coast and in the Northeast have been dealing with AOP for some time now, initially motivated by state and federal regulatory requirements, and now sometimes by legal challenge. Design practice in these state DOTs has settled on a suite of generally accepted approaches and practices calling for a higher level of geomorphic and hydraulic design than was formerly the case. Modern AOP design typically entails an interdisciplinary approach relying on various combinations of hydraulic engineers, hydrologists, fluvial geomorphologists, and biologists.
As a result of AOP design, structures have gotten larger, streambed placement and construction is now a routine practice, and 3-sided and open-bottom structures are strongly encouraged by regulators and resource agencies. Project scopes and costs have increased as compared to traditional hydraulic capacity designs. Some state DOTs have elected to address AOP programmatically while others have proceeded on a project-by-project basis. Along with these challenges has come that of institutional capacity. State DOT staffs may not have the numbers, skills, or experience, nor do many of the consultants who have traditionally functioned as extensions of DOT staffs.
The objective of this synthesis is to document state DOT practices and activities in designing, constructing, and monitoring structures that deliver aquatic organism passage.
]]></description>
      <pubDate>Mon, 10 Jul 2023 21:22:59 GMT</pubDate>
      <guid>https://rip.trb.org/View/2209731</guid>
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