969 research outputs found

    Rumble Stripes: Opportunity to Improve Safety and Retroreflectivity

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    Painted rumble stripes can provide safety benefits as well as improved retroreflectivy and paint durability. This presentation covers specifications and construction techniques. A case study will describe the recent application of rumble stripes on US 231 between Crawfordsville and Lafayette, Indiana

    Alternatives to Raised Pavement Markers (RPMs)

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    Empirical evidence shows that raised pavement markers (RPMs) can become dislodged from the pavement when struck by snowplows, presenting a road hazard. Furthermore, a dislodged RPM opens an ingress point for water to reach the sub pavement, potentially reducing the design life of the pavement. To address this issue, Indiana conducted an evaluation of centerline rumble stripes (CLRSs) as an alternative to RPMs on rural, non-interstate, roadways. Five pilot test sites consisting of 41.2 miles of roadway were constructed to evaluate CLRS performance in multiple regions of Indiana under various pavement conditions. CLRS were subsequently incorporated into INDOT’s 2013 Goals and approximately 238 project miles were programmed for construction. The project team participated in the development of a new specification for use in contract lettings after September 1, 2013. This technical report summarizes that evaluation, briefly summarizes the project background and development of CLRS specifications, provides detailed photos of a fall 2013 deployment, and summarizes the post—construction close out meeting held on December 4, 2013

    Painted Rumble Stripes: Alternatives to Raised Pavement Markers (RPMs)

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    This poster highlights research completed by the Joint Transportation Research Program (JTRP) led by Darcy Bullock, Lyles School of Civil Engineering, Purdue University, for JTRP Project SPR-3528, Alternatives to Raised Pavement Markers (RPMs). The poster includes photos taken at a construction site on State Road 25 located near Shadeland, Indiana. The top photo demonstrates how the center line corrected a driver when snow covered to avoid oncoming traffic. Photo was taken on US 231 near Country Road 800 in Tippecanoe County

    Analysis of Peer Intersection Data for Arterial Traffic Signal Coordination Decisions

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    This is the author-accepted manuscript version of Day, C.M., T.M. Brennan, H. Premachandra, J.R. Sturdevant, and D.M. Bullock, “Analysis of Peer Data on Intersections for Decisions About Coordination of Arterial Traffic Signal,”Transportation Research Record: Journal of the Transportation Research Board, No. 2259, Transportation Research Board of the National Academies, Washington, D.C., pp. 23–36, 2011, copyright National Academy of Sciences.http://dx.doi.org/10.3141/2259-03 Its corresponding poster can be found here:http://docs.lib.purdue.edu/atspmw/2016/Posters/3

    A Roundtable for Victoria M. Grieve, Little Cold Warriors: American Childhood in the 1950s

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    Dr. Thomas Field introduces a roundtable discussion of Victoria M. Grieve\u27s Little Cold Warriors: American Childhood in the 1950s, providing a synopsis of reviewer critiques before the reviewers expand on their views and the author responds

    Leveraging High Resolution Signalized Intersection Data to Characterize Discharge Headway Distributions and Saturation Flow Rate Reliability

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    As highway systems become more congested, it becomes increasingly important to understand the reliability with which we can estimate important performance measures such as volume to capacity ratios, particularly as we move toward leveraging field infrastructure to obtain real-time performance measures. In 1947, Greenshields wrote a paper that characterized “green time consumed” by “car-in-line-number” that ultimately was called headway. Average headway is one of principles used by the highway capacity manual to estimate saturation flow rate at signalized intersections. However, the current analytical techniques calculate a deterministic value for saturation flow rate that does not consider the stochastic variation of saturation flow rate. This paper reviews techniques used to estimate saturation flow rate, and proposes enhanced calculation methods to group saturation flow rate estimates by queue length. Grouping saturation flow rate estimates by queue length provides a convenient framework to evaluate saturation flow rate reliability. The inter-quartile range (25% - 75%) of saturation flow rates was calculated to be 1000vph based on Greenshields’ calculation techniques. Using the proposed enhanced calculation characterizing saturation flow rate, the inter-quartile range of saturation flow rate was shown to decrease from approximately 400 vph with 5 cars in a queue to 300 vph with 10 cars in queue. Because saturation flow rate is a fundamental input to volume-to-capacity performance measures, characterizing the stochastic variation of saturation flow rates provides a basic input for assessing how reliably one can estimate important performance measures such as volume-to-capacity ratios, as well as other performance measures that build upon volume-to-capacity ratios

    Two Alleles of NF-κB in the Sea Anemone Nematostella vectensis Are Widely Dispersed in Nature and Encode Proteins with Distinct Activities

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    BACKGROUND. NF-κB is an evolutionarily conserved transcription factor that controls the expression of genes involved in many key organismal processes, including innate immunity, development, and stress responses. NF-κB proteins contain a highly conserved DNA-binding/dimerization domain called the Rel homology domain. METHODS/PRINCIPAL FINDINGS. We characterized two NF-κB alleles in the sea anemone Nematostella vectensis that differ at nineteen single-nucleotide polymorphisms (SNPs). Ten of these SNPs result in amino acid substitutions, including six within the Rel homology domain. Both alleles are found in natural populations of Nematostella. The relative abundance of the two NF-κB alleles differs between populations, and departures from Hardy-Weinberg equilibrium within populations indicate that the locus may be under selection. The proteins encoded by the two Nv-NF-κB alleles have different molecular properties, in part due to a Cys/Ser polymorphism at residue 67, which resides within the DNA recognition loop. In nearly all previously characterized NF-κB proteins, the analogous residue is fixed for Cys, and conversion of human RHD proteins from Cys to Ser at this site has been shown to increase DNA-binding ability and increase resistance to inhibition by thiol-reactive compounds. However, the naturally-occurring Nematostella variant with Cys at position 67 binds DNA with a higher affinity than the Ser variant. On the other hand, the Ser variant activates transcription in reporter gene assays more effectively, and it is more resistant to inhibition by a thiol-reactive compound. Reciprocal Cys<->Ser mutations at residue 67 of the native Nv-NF-κB proteins affect DNA binding as in human NF-κB proteins, e.g., a Cys->Ser mutation increases DNA binding of the native Cys variant. CONCLUSIONS/SIGNIFICANCE. These results are the first demonstration of a naturally occurring and functionally significant polymorphism in NF-κB in any species. The functional differences between these alleles and their uneven distribution in the wild suggest that different genotypes could be favored in different environments, perhaps environments that vary in their levels of peroxides or thiol-reactive compounds.National Institutes of Health (CA047763); National Science Foundation (FP-91656101-0); Environmental Protection Agency (F5E11155); Conservation International Marine Management Area Science Program; Boston University (SPRInG grant); Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution; The Beacon Institute for Rivers and Estuaries; the J Seward Johnson Fund; Boston University (5 P42 ES07381
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