Evaluation of a Shared Space Alternative in Morgantown, WV

Pedestrian and vehicle movement conflicts and the associated safety and efficiency issues have always been addressed in traffic engineering based on the principle of separation through bridges, tunnels, or signals. Pioneered by Hans Monderman, shared space is a new approach in transportation design which inverts this paradigm of separation and designs streets with no demarcations or access restrictions. Shared space has been implemented in a number of cases in Europe with improved efficiency and safety. This research focuses on a specific case study for analyzing the possible implementation of shared space in the United States on the West Virginia University downtown campus in the heart of Morgantown, West Virginia.https://pdxscholar.library.pdx.edu/trec_seminar/1057/thumbnail.jp

Evaluation of Posted Speed Limits Reductions on Urban Roads with a High Percentage of Cyclists

This paper presents a before and after analysis of the impact of posted speed limit (PSL) changes on passenger car (FHWA class two vehicles) speeds in Portland, OR. The study focuses on urban roads, comparing sites that underwent a PSL 5-mph reduction (treatment sites) and sites where the PSL did not change (control sites). Sites with a high percentage of and priority for cyclists (neighborhood greenways) and sites with a more standard traffic composition were compared. Differences in speed characteristics such as mean and 85th percentile speeds, the speed variance, and the proportion of vehicles exceeding a speed threshold (relative to the posted speed limit) were evaluated on aggregate and individual scales. A series of statistical hypothesis tests were employed to assess changes in the speed characteristics among individual dataset pairs. The results suggest distinct differences between the treatment and control groups and neighborhood greenway and non-greenway sites. Although there is a high degree of variability, the treatment group experienced more decreases in the speed characteristics, and by a greater amount than the control group, on average. Within the treatment group, sites with a priority for cyclists were even more likely to experience a larger reduction in operating speeds. These results could be interpreted as link level data providing indirect yet supporting evidence for the safety in numbers hypothesis and changes in motorists’ behavior on neighborhood greenways

Data from: Statistical Inference for Multimodal Travel Time Reliability

Travel time reliability is a key metric of interest to practitioners and researchers because it affects travel choice and the economic competitiveness of urban areas. This research focuses on three travel time reliability metrics – buffer index, modified buffer index, and the relative width of travel time distributions. The key novel contributions of this research include using the multivariate delta method to prove that the sampling distributions of the three travel time reliability metrics are asymptotically normal. The asymptotic standard error for the three reliability metrics is derived. The asymptotic normality and the standard error result are used to arrive at a formula for the confidence interval. The derivations are non-parametric since they do not impose any shape requirement on travel time distributions. A case study based on a highway corridor in Portland, OR, is utilized to estimate confidence intervals for the three travel time reliability metrics for several travel time distributions with different shapes and levels of skewness. The performance of the proposed method is compared against several bootstrapping-based confidence intervals with favorable performance. Finally, upper-tailed, lower-tailed, and two-tailed one-sample hypothesis testing procedures are developed, and numerical tests show a positive performance and high statistical power for sample sizes that can be readily obtained

Statistical Inference for Multimodal Travel Time Reliability

Travel time reliability is a key metric of interest to practitioners and researchers because it affects travel choice and the economic competitiveness of urban areas. This research focuses on three travel time reliability metrics – buffer index, modified buffer index, and the relative width of travel time distributions. The key novel contributions of this research include using the multivariate delta method to prove that the sampling distributions of the three travel time reliability metrics are asymptotically normal. The asymptotic standard error for the three reliability metrics is derived. The asymptotic normality and the standard error result are used to arrive at a formula for the confidence interval. The derivations are non-parametric since they do not impose any shape requirement on travel time distributions. A case study based on a highway corridor in Portland, OR, is utilized to estimate confidence intervals for the three travel time reliability metrics for several travel time distributions with different shapes and levels of skewness. The performance of the proposed method is compared against several bootstrapping-based confidence intervals with favorable performance. Finally, upper-tailed, lower-tailed, and two-tailed one-sample hypothesis testing procedures are developed, and numerical tests show a positive performance and high statistical power for sample sizes that can be readily obtained

Advancing Bridge Technology, Task 10: Statistical Analysis and Modeling of US Concrete Highway Bridge Deck Performance -- Internal Final Report

Concrete highway bridge deck repairs represent the highest expense associated with bridge maintenance cost. In order to optimize such activities and use the available monies effectively, a solid understanding of the parameters that affect the performance of concrete bridge decks is critical. The National Bridge Inventory (NBI), perhaps the single-most comprehensive source of bridge information, gathers data on more than 600,000 bridges in all fifty states, the District of Columbia, and the Commonwealth of Puerto Rico. Focusing on concrete highway bridge deck performance, this research developed a nationwide database based on NBI data and other critical parameters that were computed by the authors, referred to as the Nationwide Concrete Highway Bridge Deck Performance Inventory (NCBDPI) database. Additionally, two performance parameters were computed from the available concrete bridge deck condition ratings (CR): Time-in-condition rating (TICR) and deterioration rate (DR). Following the aggregation of all these parameters in the NCBDPI database, filtering, and processing were performed. In addition to a basic prescriptive analysis, two types of advanced analysis were applied to the new dataset. First, binary logistic regression was applied to a subset of the data consisting of the highest and lowest DR. Second, a Bayesian survival analysis was performed on the TICR considering censored data. Through the analyses it was possible to show which parameters influence deck performance and create tools that can help agencies and bridge owners make better decisions regarding concrete bridge deck preservation

A Heuristic for the Two-Echelon Multi-Period Multi-Product Location–Inventory Problem with Partial Facility Closing and Reopening

In this paper, the two-echelon multi-period multi-product location–inventory problem with partial facility closing and reopening is studied. For each product and period, plants serve warehouses, which serve consolidation hubs, which service customers with independent, normally distributed demands. The schedule of construction, temporary partial closing, and reopening of modular capacities of facilities, the continuous-review inventory control policies at warehouses, the allocation of customer demands to hubs, and the allocation of hubs to warehouses are determined. The service levels for stockout at warehouses during lead time and the violation of warehouse and hub capacities are explicitly considered. The proposed mixed-integer non-linear program minimizes the weighted summation of the number of different facilities and logistical costs, so that the number of different facilities can be controlled. Since the proposed model is np-hard, the multi-start construction and tabu search improvement heuristic (MS-CTSIH) with two improvement strategies and the modified MS-CTSIH incorporating both strategies are proposed. The experiment shows that the two improvement strategies appear non-dominated, and the modified MS-CTSIH yields the best results. The comparison of the modified MS-CTSIH and a commercial solver on a small instance shows the efficiency and effectiveness of the modified MS-CTSIH. The sensitivity analyses of problem parameters are performed on a large instance

Comparisons of Linear Regression Models for Properties of Alkaliactivated Binder Concrete

Concrete with alkali-activated binder (AAB) is increasingly considered as a better alternative to conventional portland cement (PC) concrete due to its superior sustainable and green properties. In order to promote the practical usage of AAB concrete, a previous study by the present authors proposed models on correlations among their mechanical and nondestructive properties. The present study extends the previous knowledge by proposing new improved models using linear regressions to predict compressive strengths and modulus of elasticity from ultrasonic pulse velocities. The models are developed for both unstressed and stressed AAB concrete with different curing temperatures. The accuracies of the models are compared with both sum of squares due to errors (SSE) and R2 depending on the type of equations; and the new models are found to be more accurate compared to the previous models

COMPARISONS OF LINEAR REGRESSION MODELS FOR PROPERTIES OF ALKALIACTIVATED BINDER CONCRETE

Concrete with alkali-activated binder (AAB) is increasingly considered as a better alternative to conventional portland cement (PC) concrete due to its superior sustainable and green properties. In order to promote the practical usage of AAB concrete, a previous study by the present authors proposed models on correlations among their mechanical and nondestructive properties. The present study extends the previous knowledge by proposing new improved models using linear regressions to predict compressive strengths and modulus of elasticity from ultrasonic pulse velocities. The models are developed for both unstressed and stressed AAB concrete with different curing temperatures. The accuracies of the models are compared with both sum of squares due to errors (SSE) and R2 depending on the type of equations; and the new models are found to be more accurate compared to the previous models

NONDESTRUCTIVE CHARACTERIZATIONS OF ALKALI ACTIVATED FLY ASH AND/OR SLAG CONCRETE

In recent years, the alkali activated material (AAM) concrete is emerging as a sustainable and green alternative to traditional portland cement (PC) concrete. In order to widen its applications, more information on correlations among its mechanical and physical properties is required. To address the issue this paper studies the relationships between compressive strength, dynamic modulus of elasticity, and ultrasonic pulse velocity of various AAM concrete mixtures with fly ash and/or slag as precursors cured at different temperatures at both unstressed and stressed conditions. The results show that effective relationships can be established to predict compressive strength and modulus of elasticity from the ultrasonic pulse velocity with reasonable accuracy for wide range of AAM concrete mixes