Assessing tradeoffs between safety and operations: an analytical framework

Roadway improvements are often made based on safety or operations. While each factor is important, consideration of one factor may impact another negatively. The tradeoffs between factors are often not well understood. The failure or inability to consider these impacts is of particular concern, as a general improvement in one area (ex. operations), may have adverse results on another;This dissertation presents a methodology to link safety and operations in order to determine the tradeoffs of improvements. A zero-inflated Poisson model was selected to model safety and was specified within a hierarchical Bayesian framework. Bayesian p-values were utilized to establish model confidence and found that the model which was developed appeared to fit the data reasonably well;Model results indicated that the approach speed limit, opposing approach speed limit, right turn lane length, maximum green time for the through movement, median width, land use and left turn movement all had an effect on the number of crashes per site per approach at different levels of severity. Protected/permitted phasing and through movement had an effect on crashes at all types of severities. Protected/permitted phasing had an effect on the overall number of crashes per site by approach when not considering severity;Twenty three case studies were simulated to determine how safety or operational countermeasures impacted their counterpart. Impacts were assessed at the approach level and for the intersection as a whole. Benefit-Cost analysis was performed to further quantify the financial impacts of selected countermeasures;Based on the simulations, the impact of safety changes on operations could be considered to be more negative than positive. Benefit-Cost analysis found that, for safety improvements, only four of the ten study sites produced a B/C ratio greater than 1.0. The impacts on safety of operational countermeasures were generally found to be positive. Eleven of the thirteen operational study sites produced a B/C ratio greater than 1.0

Baryon-number -flavor separation in the topological expansion of QCD

Gauge invariance of QCD dictates the presence of string junctions in the wave functions of baryons. In high-energy inclusive processes, these baryon junctions have been predicted to induce the separation of the flows of baryon number and flavor. In this paper we describe this phenomenon using the analog-gas model of multiparticle production proposed long time ago by Feynman and Wilson and adapted here to accommodate the topological expansion in QCD. In this framework, duality arguments suggest the existence of two degenerate junction-antijunction glueball Regge trajectories of opposite $\cal{C}$-parity with intercept close to 1/2. The corresponding results for the energy and rapidity dependence of baryon stopping are in reasonably good agreement with recent experimental findings from STAR and ALICE experiments. We show that accounting for correlations between the fragmenting strings further improves agreement with the data, and outline additional experimental tests of our picture at the existing (RHIC, LHC, JLab) and future (EIC) facilities.Comment: 27 pages, 15 figure

Evaluation of Pavement Markings on Low-Volume Rural Roadways in Iowa

Many rural roadways in Iowa have centerline and/or edgeline pavement markings. The current Manual on Uniform Traffic Control Devices (MUTCD), however, requires centerline and/or edgeline pavement markings only along streets and roadways with traffic volumes much greater than 400 vehicles per day (the volume-based definition of a low-volume roadway in the MUTCD). This project was initiated to gather and summarize information about the state of practice related to the installation and maintenance of pavement markings along low-volume rural roadways in Iowa. Additional information was also collected to provide more guidance in the pavement-marking decision-making process. The tasks completed include an examination and summary of past research, the collection of legal input related to the use of pavement markings in Iowa, and a survey of Iowa county engineers that focused on their current pavement-marking practices. A basic safety benefit-cost evaluation of pavementmarking applications was also performed. Overall, the literature on the effectiveness of pavement markings and their safety impacts is limited. A number of studies have been completed with varying levels of robustness and reliability in their results. The Highway Safety Manual includes crash modification factors for the installation of centerline markings that it indicates should be used with caution, and one for the installation of edgeline and centerline markings that equates to a 24 percent total serious and minor-injury crash reduction. A more recent study from Louisiana also found a 15 percent reduction in total crashes after the addition of edgelines. The legal input acquired as part of this project was generally common knowledge. It indicated that once a traffic control device has been installed, the jurisdiction must properly and adequately maintain it. The survey completed found that, of the great majority of the respondents (97 percent), painted centerline/no passing zones and edgelines on at least some of their paved low-volume rural roadways. A much smaller percentage took this approach, or just painted centerlines/no passing zones, along their seal-coated roadways. The basic cost-benefit evaluation found that the percentage of crash reduction needed from pavement markings to make them beneficial was very low (i.e., 5.1 percent, at most). Overall, it was concluded that pavement markings are widely used in Iowa along low-volume paved roadways and sometimes seal-coated roadways. In addition, there is a safety benefit to the installation of pavement markings. but the research into that impact is limited, particularly along low-volume roadways. It is recommended that further analysis be completed on potential pavement-marking safety impacts, that a pavement-marking database be developed, and that a committee be initiated to help develop policies related to pavement-marking removal

Evaluation of LIDAR-derived terrain data in highway planning and design

Surface terrain information is required to economically site new or relocate existing infrastructure facilities and make final design plans. Currently, ground surveying and photogrammetric mapping are the methods used by DOTS to acquire these data. Both methods are time and resource intensive since they require significant data collection and reduction to provide the level of detail necessary for facility location. The research presented here investigates a new method for collecting elevational data: LIDAR (Light Detection and Ranging). A pilot area previously mapped using photogrammetry by the Iowa Department of Transportation Office of Photogrammetry was selected, and surface grids of varying resolutions were developed from photogrammetric and LIDAR data. These were compared to determine the elevational accuracy of LIDAR. Additionally, the location processes of Iowa, Virginia and New Mexico are documented to determine how LIDAR data collection can be integrated into existing processes. The experiences of the Iowa DOT in the use of LIDAR are also presented

Asymptotic Behavior of the Einstein-Yang-Mills-Dilaton System for a Closed Friedmann-Lemaitre Universe

We study the coupled Einstein-Yang-Mills-Dilaton (EYMD) equations for a Fried\-mann-Le\-mai\-tre universe with constant curvature $k=1$. Our detailed analysis is restricted to the case where the dilaton potential and the cosmological constant vanish. Also assuming a static gauge field, we present analytical and numerical results on the behavior of solutions of the EYMD equations. For different values of the dilaton coupling constant we analyze the phase portrait for the time evolution of the dilaton field and give the behavior of the scale factor. It turns out that there are no inflationary stages in this model.Comment: 18 pages, Uuencoded gzip compressed tar file containing a latex file and 12 figures. The epsfig.sty is neede

Evaluating Remotely Sensed Images for Use in Inventorying Roadway Infrastructure Features

The main objective of this research was to evaluate the use of remotely sensed images as a method to facilitate accurate and rapid collection of large quantities of inventory data. Images collected from either an airplane or satellite can be collected fairly rapidly for large areas without locating on-road or interfering with traffic. With the launching of the IKONOS satellite, resolutions of 1 meter can be practically obtained from space. Image resolution of as high as 1-inch are possible with aerial photography. Aircraft can be flown at higher altitudes for lower resolutions. Since cost typically decreases as resolution decreases, one of the goals of the research was to test images at different levels of resolution to make recommendations on the minimum necessary to collect specific inventory features. This is especially important since many agencies already have access to low resolution images such as the USGS orthophoto quarter quads. Besides the advantage of more rapid data collection, use of remote sensing may allow collection of data which was previously difficult to obtain from conventional methods

The failure of cosmological perturbation theory in the new ekpyrotic and cyclic ekpyrotic scenarios

Cosmological perturbation theory fails in the new ekpyrotic and cyclic ekpyrotic scenarios, before the scale factor of the Universe reaches zero. As a result, a recently-proposed recipe for evolving the curvature perturbation through the bounce in these scenarios cannot be justified.Comment: 10 pages. v2: Logic of the demonstration of non-linearity stated more explicitely. Remarks on non-singular bounces removed for inclusion in a later paper. v3: As accepted by Phys Lett B v4: Comment on the paper of Banks and Fischler removed following its withdrawal; more precise abstrac

Closed-String Tachyons and the Hagedorn Transition in AdS Space

We discuss some aspects of the behaviour of a string gas at the Hagedorn temperature from a Euclidean point of view. Using AdS space as an infrared regulator, the Hagedorn tachyon can be effectively quasi-localized and its dynamics controled by a finite energetic balance. We propose that the off-shell RG flow matches to an Euclidean AdS black hole geometry in a generalization of the string/black-hole correspondence principle. The final stage of the RG flow can be interpreted semiclassically as the growth of a cool black hole in a hotter radiation bath. The end-point of the condensation is the large Euclidean AdS black hole, and the part of spacetime behind the horizon has been removed. In the flat-space limit, holography is manifest by the system creating its own transverse screen at infinity. This leads to an argument, based on the energetics of the system, explaining why the non-supersymmetric type 0A string theory decays into the supersymmetric type IIB vacuum. We also suggest a notion of `boundary entropy', the value of which decreases along the line of flow.Comment: 24 pages, Harvmac. 2 Figures. Typos corrected and reference adde

Semiclassical vs. Exact Solutions of Charged Black Hole in Four Dimensions and Exact O(d,d) Duality

We derive a charged black hole solution in four dimensions described by $SL(2,R)\times SU(2)\times U(1)/U(1)^2$ WZW coset model. Using the algebraic Hamiltonian method we calculate the corresponding solution that is exact to all orders in ${1\over k}$. It is shown that unlike the 2D black hole, the singularity remains also in the exact solution, and moreover, in some range of the gauge parameter the space-time does not fulfil the cosmic censor conjecture, $i.e.$ we find a naked singularity outside the black hole. Exact dual models are derived as well, one of them describes a 4D space-time with a naked singularity. Using the algebraic Hamiltonian approach we also find the exact to all orders $O(d,d)$ transformation of the metric and the dilaton field for general WZW coset models and show the correction with respect to the transformations in one loop order.Comment: 42 pages, (typographical errors in pages 33 and 35

Duality Invariance of Cosmological Perturbation Spectra

I show that cosmological perturbation spectra produced from quantum fluctuations in massless or self-interacting scalar fields during an inflationary era remain invariant under a two parameter family of transformations of the homogeneous background fields. This relates slow-roll inflation models to solutions which may be far from the usual slow-roll limit. For example, a scale-invariant spectrum of perturbations in a minimally coupled, massless field can be produced by an exponential expansion with $a\propto e^{Ht}$, or by a collapsing universe with $a\propto (-t)^{2/3}$.Comment: 5 pages, Latex with Revtex. Hamiltonian formulation added and discussion expanded. Version to appear in Phys Rev