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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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    <item>
      <title>Long-Term Construction and Maintenance Cost Comparison for Road Stream Crossings: Traditional Hydraulic Design vs. Aquatic Organism Passage Design</title>
      <link>https://trid.trb.org/View/1515590</link>
      <description><![CDATA[The design and installation of road stream crossings to accommodate fish and aquatic organism passage is increasingly becoming a priority for state and federal regulatory agencies throughout the United States to meet the mandates of the Clean Water Act, and in the case with federally protected migratory species, the Endangered Species Act. While progress has been made in providing fish passage at dams on many river systems, these agencies realize that road crossings are much more numerous than dams and may have a greater impact on fish passage than dams as supported by inventories of road crossings conducted to assess aquatic passage in the Pacific Northwest. In addition, extreme weather events and other climate change concerns are driving discussions toward a new paradigm for infrastructure investment decisions that considers the overall life-cycle costs of structures. The higher costs of installing effective aquatic organism passage structures are often a concern for designers and transportation agencies. While it is clear that the upfront costs of larger structures may increase with effective aquatic organism passage designs, long term savings may be achieved by reducing the risk of road failure, reducing the need for periodic maintenance, increasing the life span of the structure, and reducing the cost of mitigation for open water and wetland impacts. There are three general approaches to the drainage design of culverts that are in use across the nation, though variations in application occur: (1) Traditional or conventional hydraulic design; (2) Aquatic organism passage (AOP) design (HEC-26 and Bankfull width times a safety factor); and (3) Stream simulation design (geomorphic design). Multiple states and federal entities have developed guidance regarding stream crossing design approaches, but the guidance focuses primarily on design approaches mentioned above and design options. While design options have been studied, research is needed to evaluate the long-term costs and benefits of aquatic organism passage design which can support decision making on project design and funding. The objectives of the overall Task 93 project research are to: (1) Quantify the long-term costs of road stream crossings that span the bankfull width of a waterway (aquatic organism passage design) in order to provide an accurate picture of the total life-cycle cost of the structure; and (2) Compare costs of aquatic organism passage design-based structures to the costs of traditional hydraulic design structures.]]></description>
      <pubDate>Mon, 18 Jun 2018 12:26:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/1515590</guid>
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      <title>Culvert Length and Interior Lighting Impacts to Topeka Shiner Passage</title>
      <link>https://trid.trb.org/View/1489905</link>
      <description><![CDATA[Culverts can act as barriers to fish passage for a number of reasons including insufficient water depth or excess velocity. In addition, concern is being raised over behavioral barriers where culvert conditions elicit an avoidance response that deters or slows fish movement. Long culverts can block sunlight creating a potential behavioral barrier as fish approach a long, dark culvert. Scant information exists on low light as a potential barrier to fish passage, particularly with warm water species, such as the federally endangered Topeka Shiner. As some older culverts are being replaced with longer total lengths to improve safety by extending the culvert through re-engineered road embankments, information is needed to 1) determine when and if light mitigation strategies are necessary, and 2) to design appropriate light mitigation strategies if necessary. Based on literature review, field monitoring, and laboratory experiments, the effect of light on fish passage for Topeka Shiner and other small prairie stream fish was indiscernible. Therefore, no light mitigation for large box culverts (up to 150 feet in length) can be recommended for similar fish communities. Culverts that are very long or have very small openings may benefit from additional light.]]></description>
      <pubDate>Mon, 04 Dec 2017 18:11:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/1489905</guid>
    </item>
    <item>
      <title>Long-Term Bed Degradation in Maryland Streams (Phase III Part 2): Urban Streams in the Piedmont Plateau Province</title>
      <link>https://trid.trb.org/View/1464131</link>
      <description><![CDATA[Estimation of potential long-term down-cutting of the streambed is necessary for evaluation and design of bridges for scour and culverts for fish passage. The purpose of this study has been to improve predictions of this potential long-term bed degradation (LTBD) in Maryland streams through the measurement and analysis of streambed and waterway structure survey data and bridge plans. Long-term bed degradation was defined as the vertical change in the channel profile other than that caused by local or contraction scour. A total of 41 sites in Frederick, Carroll, Montgomery, Baltimore, and Howard counties, Baltimore City, and Washington, DC, were selected for data collection. Drainage areas of these sites in the Piedmont Plateau physiographic provinces ranged from 0.2−62.1 mi². At each sampling site, the vertical drop at the outlet of the structure was measured with a pocket rod and a hand level. These rapid measurements were conducted where a step, a series of steps, a steep section, or a riprap-protected streambed was at the outlet of a culvert or a bridge with a paved or riprap-protected invert or downstream apron. Four of the six factors that may influence a site’s risk of LTBD were also investigated. These include (1) the valley slope, (2) the effective floodplain width, (3) discharge, and (4) downstream channel entrenchment. The possibility of developing regional relations between LTBD and either watershed area or percent impervious area was evaluated for the physiographic province, but the data were inconclusive. Two relations between LTBD and the risk factors were examined: LTBD and valley slope; and LTBD and an index combining Factors 1-4. A comparison of the resulting equations revealed that valley slope was as good a predictor of the susceptibility of a site to LTBD as the index that required additional data and considered more parameters. The relation between valley slope and LTBD was recommended to estimate LTBD for streams with slopes of less than 0.03 ft/ft. The relation should not be applied, however, to structures located in deep deposits of sediment created by backwater from dams or other structures or to structures located in streams with evidence of active channel degradation. The development of rate relationships for LTBD was also considered, but the number of available structure plans was insufficient to develop a rate relation. Future research on LTBD in Maryland should include the development of a method to include the effectiveness of downstream bed controls in limiting degradation, and the development of a rate relation should be explored further.]]></description>
      <pubDate>Mon, 15 May 2017 15:17:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/1464131</guid>
    </item>
    <item>
      <title>Culvert Designs for Aquatic Organism Passage: Culvert Design Practices Incorporating Sediment Transport</title>
      <link>https://trid.trb.org/View/1409697</link>
      <description><![CDATA[The design of culverts to accommodate aquatic organism passage (AOP) requires an understanding of organism habitat requirements, swimming ability and migration needs, as well as an understanding of how a culvert design will perform in a specific geomorphic context. This report documents existing reports on culvert design for AOP in Minnesota and nationally. The review is designed to build upon the work of Hansen et al. 2009 and 2011 to: 1) summarize current aquatic organism passage practices, 2) summarize aquatic organism passage needs for Minnesota species, 3) discuss the importance of roughness or streambed sediment within a culvert in different systems (high, medium, or low slope) in single and multiple barrel systems, and 4) summarize physical experiments of sediment transport and geomorphic processes through culverts.]]></description>
      <pubDate>Wed, 08 Jun 2016 14:55:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/1409697</guid>
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    <item>
      <title>Analysis of Projected Replacement and Costs for Potential Aquatic Barriers Maintained by MaineDOT</title>
      <link>https://trid.trb.org/View/1398948</link>
      <description><![CDATA[This project continued development of the Maine Barrier Database, integrating MaineDOT crossings with that database, and supporting the development of a tool for viewing aquatic habitat data in association with stream crossings. The final dataset includes important attributes associated with fisheries habitat values, as well as cost estimates for evaluating addition of projects to work plans. This research has been of great value in enabling the speedy delivery of preliminary assessments of aquatic habitat that might affect MaineDOT projects. A cost model for providing fish passage is applied to data generated and results show order-of-magnitude implications for various replacement strategies.]]></description>
      <pubDate>Mon, 21 Mar 2016 16:47:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1398948</guid>
    </item>
    <item>
      <title>An Evaluation of Trout Passage through Six Highway Culverts in Montana</title>
      <link>https://trid.trb.org/View/1376129</link>
      <description><![CDATA[This article examines the combinations of water velocity and passage length in highway culverts that will allow or prevent the passage of rainbow trout, brown trout, cutthroat trout and brook trout. Trapping and electrofishing were used to determine fish passage through six 45-93-m-long corrugated metal culverts. Because of the similarity of passage relations among species, the spawning rainbow trout relation was used as the general criterion for trout passage. This relation indicated that fish could swim distances of 10, 30, 50, 70, and 90 m with mean bottom velocities up to 0.96, 0.80, 0.74, 0.70, and 0.67 m/s, respectively. This information is useful for designing new culverts and for identifying existing culverts that prevent or limit the passage of trout.]]></description>
      <pubDate>Wed, 09 Dec 2015 11:06:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/1376129</guid>
    </item>
    <item>
      <title>Fish Passage Behavior for Severe Hydraulic Conditions in Baffled Culverts</title>
      <link>https://trid.trb.org/View/1299939</link>
      <description><![CDATA[Laboratory tests were conducted with brown trout to evaluate their ability to pass through a small, baffled prototype-scale culvert under a variety of culvert slopes and discharge conditions. The culvert was 18.3 m long and 0.60 m in diameter with 0.15D baffle height and 0.9D spacing, where D is the culvert inside diameter. An inverse relationship was observed between fish passage success and flow rate and/or culvert slope. The influence of the sample fish population and the length of the individual fish on passage rates were investigated; the data showed that the brown trout fish passage sample size evaluated in this study (25 per test) was sufficiently large to minimize sample size dependency. The elapsed time required for fish to traverse the culvert decreased with increasing hydraulic difficulty primarily owing to diminishing resting zones. The behavior of fish traversing the culvert was observed and reported, including resting/staging zone locations.]]></description>
      <pubDate>Wed, 26 Feb 2014 10:41:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/1299939</guid>
    </item>
    <item>
      <title>Design for Fish Passage for Bridges and Culverts</title>
      <link>https://trid.trb.org/View/1268796</link>
      <description><![CDATA[The Federal Highways Administration and Washington State University are collaborating to produce Hydraulic Engineering Circular 26: "Design of Fish Passage for Bridges and Culverts"; a comprehensive manual for the design or retrofit of a stream crossing to meet fish passage requirements. Input from State Departments of Transportation, non-governmental organizations, and other interested parties will be combined with new research and an extensive literature review to compile design methods, culvert and stream assessment techniques, case studies, and design examples. The manual will provide a set of guidelines to any party interested in the design or retrofit of culverts and bridges to meet fish passage requirements, and is intended to streamline the design process.]]></description>
      <pubDate>Tue, 03 Dec 2013 08:52:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1268796</guid>
    </item>
    <item>
      <title>Identifying Culvert Design Parameters that Correlate with Fish Passage Success</title>
      <link>https://trid.trb.org/View/1256824</link>
      <description><![CDATA[The Ohio Department of Transportation (ODOT) maintains approximately 90,000 culverts across the state. For every bridge, there are 6 culverts. This proposal seeks to understand the percentage of existing culverts that allow for fish passage. Further, the proposal wishes to use data from the existing culverts that do pass fish to identify design variables that strongly correlate with fish passage success in Ohio. Until recently hydraulic design of culverts in Ohio was based primarily on conveyance of large flood events. With the issuance of a new nationwide permit ODOT is now required to design new culverts to allow aquatic organism passage. Specifically, all new culverts are required to pass the unimpeded bankfull discharge. This recommendation comes primarily from migration studies of west coast salmon species. A recently completed report questions the effectiveness of bankfull culverts in Ohio but was unable to determine successful design characteristics due to an insufficient number of properly functioning bankfull culverts in Ohio. The proposed research compliments the study yet refocuses the question to fish passage success in all existing ODOT culverts. There are two primary benefits to this new approach. First, the proposal will be able to understand the percentage of culverts that already pass fish using existing design criteria. It is likely that many existing culverts in the ODOT system already allow for fish passage, thus indicating that under certain circumstances standard design practices are sufficient to address the new fish passage goal. Second, by including all existing culverts, the number of culverts available for evaluation increases substantially thus increasing the strength of the study and therefore the likelihood that design variables which are correlated with fish passage success in Ohio can be identified.  Objectives and Goals of the Study The overarching objective of this proposal is to understand the extent to which existing culverts in the ODOT system allow fish passage and to use the identified successful culverts to determine ranges of design variables that are important to passage success. One tool will be developed while two questions will be answered: Tool: 	A standard method for determining whether an existing culvert passes fish. Questions: 1) What percentage of culverts in Northeast Ohio allow fish movement?  2) What range of standard design parameters are correlated with fish passage success?]]></description>
      <pubDate>Sat, 20 Jul 2013 01:01:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/1256824</guid>
    </item>
    <item>
      <title>Hydraulic Loss Coefficients for Culverts</title>
      <link>https://trid.trb.org/View/1226188</link>
      <description><![CDATA[Traditional culvert applications were designed by determining the minimum culvert size that will pass the specified design flood. In recent years, culvert performance objectives and designs have been expanded to include other considerations such as improving fish and/or terrestrial animal passage and rehabilitating old, deteriorated culverts. This project evaluated culvert geometries associated with these new applications to develop the hydraulic relationships, including loss coefficients. The report will be of interest to hydraulic engineers and environmental staff.]]></description>
      <pubDate>Thu, 27 Dec 2012 14:47:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/1226188</guid>
    </item>
    <item>
      <title>Culvert Roughness Elements for Native Utah Fish Passage: Phase II</title>
      <link>https://trid.trb.org/View/1147974</link>
      <description><![CDATA[Native fishes have become an increasingly important concern when designing fish passable culverts. Many operational culverts constrict waterways which increase velocities and prevent upstream passage of small fish species. The current method to ensure fish passage is to match the average cross sectional velocity to the sustained swim speed of the fish. This study investigates the passage rates of leatherside chub (Lepidomeda aliciae) and speckled dace (Rhinichthys osculus) at three sites (an arch culvert with substrate bottom, box culvert with bare bottom, and a stream section with no culvert) located on Salina Creek near Salina, UT. It was found that fish were able to pass through all of the sites. However, fish were able to take advantage of the habitat within the culvert that had a substrate bottom more effectively than within the culvert that had no substrate within the barrel. This was reflected in population density estimates at each of the three test sites for each species. It was also found that the substrate at the arch culvert and stream sites scaled with the fish measured in this study. The D50 and D84 were 44 and 205 mm at the arch culvert site and 26 and 126 mm at the stream site. The average fish length was 76 mm for the chub and 64 mm for the dace. It is believed that placing substrate that scales with fish length within the culvert will provide enough velocity heterogeneity to allow the fish to successfully pass.]]></description>
      <pubDate>Wed, 22 Aug 2012 15:37:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/1147974</guid>
    </item>
    <item>
      <title>Long-Term Bed Degradation in Maryland Streams (Phase 2): Blue Ridge and Western Piedmont Provinces</title>
      <link>https://trid.trb.org/View/1141361</link>
      <description><![CDATA[Estimation of potential long-term down-cutting of the stream bed is necessary for evaluation and design of bridges for scour and culverts for fish passage. The purpose of this study has been to improve predictions of this potential long-term bed degradation (LTBD) in Maryland streams through the measurement and analysis of stream bed and waterway structure survey data and bridge plans. Long-term bed degradation was defined as the vertical change in the channel profile other than that caused by local or contraction scour. A total of 30 sites—23 bridges, 2 culverts, 2 utility crossings, 2 embankment walls, and 1 concrete ford—in Frederick, Carroll, and Montgomery counties were selected for data collection. Drainage areas of these sites in the Blue Ridge and Piedmont physiographic provinces ranged from 1.7-25.9 mi². At each sampling site, the vertical drop at the outlet of the structure was measured with a pocket rod and a hand level. These rapid measurements were conducted where a step, a series of steps, a steep section, or a riprap-protected streambed was at the outlet of a culvert or a bridge with a paved or riprap-protected invert or downstream apron. Six factors that may influence a site’s risk of LTBD in the three western Maryland provinces were also investigated. These include (1) the valley slope, (2) the effective floodplain width, (3) discharge, (4) downstream channel entrenchment, (5) bed material size, and (6) downstream grade controls. The possibility of developing regional relations between watershed area and LTBD was evaluated for each physiographic province, but the data were inconclusive. Three relations between LTBD and five of the risk factors were examined: LTBD and valley slope; LTBD and an index combining Factors 1-4; and LTBD and an index combining Factors 1-5. A comparison of the resulting equations revealed that valley slope was as good a predictor of the susceptibility of a site to LTBD as the two indices that required additional data and considered more parameters. The relation between valley slope and LTBD was recommended to estimate LTBD for streams with slopes of less than 0.027 ft/ft. The relation will not apply, however, to structures located in deep deposits of sediment created by backwater from dams or other structures or to structures located in streams with evidence of active channel degradation. The development of rate relationships for LTBD was also considered, but the number of available structure plans was insufficient to develop a rate relation. Future research on LTBD in Maryland should include the development of a method to include the effectiveness of downstream bed controls in limiting degradation, and the development of a rate relation should be explored further.]]></description>
      <pubDate>Wed, 20 Jun 2012 16:38:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1141361</guid>
    </item>
    <item>
      <title>Performance Assessment of Oversized Culverts to Accommodate Fish Passage</title>
      <link>https://trid.trb.org/View/1123295</link>
      <description><![CDATA[In Minnesota there is not a standard culvert design used at road crossings to improve aquatic organism or fish passage. The design process for fish passage in Minnesota is currently based on the knowledge and experience of local county, state and Department of Natural Resources personnel. The design methodology attempts to maintain the natural stream dimensions, pattern and profile through the culvert crossing. If designed properly aquatic organisms and fish that can make it upstream to the culvert should be able to pass through the culvert. This research was conducted to better understand the hydraulic conditions related to the practice of recessing culverts and other fish passage design elements over a range of landscapes in Minnesota. The design elements analyzed included bankfull width, slope, channel materials, side barrels and recessed culverts. Nineteen culvert sites were surveyed around the state. The main criterion used to evaluate performance of the culverts was the presence or absence of adequate sediment in the recessed culvert barrel. Six of the fourteen sites with recessed barrels had no sediment accumulation. A likely reason that these culverts lack sediment was increased velocities due to improper sizing relative to bankfull channel width and the accumulation of sediment in the side barrels. Wider Rosgen “C” type channels also correlated with performance issues related to culvert design.]]></description>
      <pubDate>Tue, 29 Nov 2011 16:32:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/1123295</guid>
    </item>
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      <title>Factors for Improved Fish Passage Waterway Construction</title>
      <link>https://trid.trb.org/View/1108678</link>
      <description><![CDATA[Streambeds are important fish passageways in Oregon; they provide for the necessary habitats and spawning cycles of a healthy fish population. Oregon state law requires that hydraulic structures located in water properly provide fish passage. Increasingly stringent state and federal regulations apply to these fish passageways, and designers must become more cognizant of conditions over a range of flows to accommodate fish movement and avoid expensive structural failure of these passageways. Fish passage structures are built when roads cross streambeds and may include culverts, or bridges. When these structures are built, the streambeds are re-created using a technique called “roughened channels”. Roughened channels are man-made stream channels utilized for re-creating the hydraulics necessary for adequate stream passage, and this may include new constructions or retrofits of older, inadequate structures. Mixtures of materials are used to construct the bed of roughened channels, ranging from fines such as sand, silt and gravel to coarse elements like cobbles and boulders. Fines are a critical element in limiting permeability of the constructed bed thus keeping stream flow at the surface of the roughened channel during low flow periods. This report discusses work of a research project designed to discover factors that are key to successful long-term implementation of fish passageways, especially focused on the construction process. Areas of inquiry postulated in this study are that failures experienced in actual installations may be due to inadequate range and/or mix of soil and rock material gradation; unexpected water velocity, especially during high flows; inadequate mixing of rock and soil materials during construction; and inadequate compaction of rock and soil materials during construction. This report suggests that several factors may be especially important considerations in fish passage success. These factors are the relationship of downstream slope to structure slope, well-graded fine soil materials in the channel fill (improved by choice of fill source), and frequent site visits. Improving fish passages for cost-efficient fish movement is a priority for government agencies such as Oregon Department of Transportation (ODOT) and Oregon Transportation Research and Education Consortium (OTREC).]]></description>
      <pubDate>Fri, 05 Aug 2011 16:09:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/1108678</guid>
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    <item>
      <title>Stream Simulation for Aquatic Organism Passage at Road–Stream Crossings</title>
      <link>https://trid.trb.org/View/1107507</link>
      <description><![CDATA[Historically, road–stream crossing structures were designed on the basis of the hydraulic capacity of the structure for a specific design flood without consideration of aquatic species or the swimming and jumping abilities of a single target fish species and life stage during its migration, and ignored the movement needs of other adult fish, juvenile fish, and aquatic organisms occupying the stream. Hydraulic designs typically constrict the channel, create flow hydraulics and channel conditions that are markedly dissimilar from those in the natural channel, and impede the movement of most other nontarget fish and aquatic organisms along the stream corridor. The stream simulation approach for designing road–stream crossing structures was recently adopted by the U.S. Department of Agriculture Forest Service as a pragmatic and sustainable long-term solution to maintain passage for all aquatic organisms at all life stages at road–stream crossings while meeting vehicle transportation objectives. This study shows how the stream simulation design process integrates fluvial geomorphology concepts with engineering principles to design a natural and dynamic channel through the road–stream crossing structure. The premise of stream simulation is that the creation of channel dimensions and characteristics similar to those in the adjacent natural channel will enable fish and other aquatic organisms to experience no greater difficulty moving through the structure than if there were no crossing. Stream simulation channels are designed to adjust laterally and vertically to a wide range of floods and sediment or wood inputs without compromising the movement needs of fish and other aquatic organisms or the hydraulic capacity of the structure.]]></description>
      <pubDate>Wed, 27 Jul 2011 13:42:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/1107507</guid>
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