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

Quantifying Opportunity Costs in Sequential Transportation Auctions for Truckload Acquisition

The principal focus of this research is to quantify opportunity costs in sequential transportation auctions. This paper focuses on the study a transportation marketplace with time-sensitive truckload pickup-and-delivery requests. In this paper, two carriers compete for service requests; each arriving service request triggers an auction where carriers compete with each other to win the right of servicing the load. An expression to evaluate opportunity costs is derived. This paper shows that the impact of evaluating opportunity costs is dependent on the competitive market setting. A simulation framework is used to evaluate different strategies. Some results and the overall simulation framework are also discussed

Modeling Carrier Behavior in Sequential Auction Transportation Markets

Online markets for transportation services, in the form of Internet sites that dynamically match shipments (shippers? demand) and transportation capacity (carriers? offer) through auction mechanisms are changing the traditional structure of transportation markets. A general framework for the study of carriers? behavior in a sequential auction transportation marketplace is provided. The unique characteristics of these marketplaces and the sources of difficulty in analyzing the behavior of these marketplaces are discussed. Learning and behavior in a sequential Vickrey auction marketplace is analyzed and simulated. Some results and the overall behavioral framework are also discussed

Auction Settings Impacts on the Performance of Truckload Transportation Marketplaces

This paper compares the performance of different sequential auction settings for the procurement of truckload services. In this environment, demands arrive randomly over time and are described by pick up, delivery locations and hard timewindows. Upon demand arrival, carriers compete for the loads. Different auction and information disclosure settings are studied. Learning methodologies are discussed and analyzed. Simulation results are presented

Effective Study: Development and Application of a Question-Driven, Time-Effective Cardiac Magnetic Resonance Scanning Protocol

BACKGROUND: Long scanning times impede cardiac magnetic resonance (CMR) clinical uptake. A “one‐size‐fits‐all” shortened, focused protocol (eg, only function and late‐gadolinium enhancement) reduces scanning time and costs, but provides less information. We developed 2 question‐driven CMR and stress‐CMR protocols, including tailored advanced tissue characterization, and tested their effectiveness in reducing scanning time while retaining the diagnostic performances of standard protocols. METHODS AND RESULTS: Eighty three consecutive patients with cardiomyopathy or ischemic heart disease underwent the tailored CMR. Each scan consisted of standard cines, late‐gadolinium enhancement imaging, native T1‐mapping, and extracellular volume. Fat/edema modules, right ventricle cine, and in‐line quantitative perfusion mapping were performed as clinically required. Workflow was optimized to avoid gaps. Time target was 30% (CMR: from 42±8 to 28±6 minutes; stress‐CMR: from 50±10 to 34±6 minutes, both P45% of cases. Quality grading was similar between the 2 protocols. Tailored protocols did not require additional staff. CONCLUSIONS: Tailored CMR and stress‐CMR protocols including advanced tissue characterization are accurate and time‐effective for cardiomyopathies and ischemic heart diseas

Predictors of adverse prognosis in COVID-19: A systematic review and meta-analysis

Background: Identification of reliable outcome predictors in coronavirus disease 2019 (COVID-19) is of paramount importance for improving patient's management. Methods: A systematic review of literature was conducted until 24 April 2020. From 6843 articles, 49 studies were selected for a pooled assessment; cumulative statistics for age and sex were retrieved in 587 790 and 602 234 cases. Two endpoints were defined: (a) a composite outcome including death, severe presentation, hospitalization in the intensive care unit (ICU) and/or mechanical ventilation; and (b) in-hospital mortality. We extracted numeric data on patients’ characteristics and cases with adverse outcomes and employed inverse variance random-effects models to derive pooled estimates. Results: We identified 18 and 12 factors associated with the composite endpoint and death, respectively. Among those, a history of CVD (odds ratio (OR) = 3.15, 95% confidence intervals (CIs) 2.26-4.41), acute cardiac (OR = 10.58, 5.00-22.40) or kidney (OR = 5.13, 1.78-14.83) injury, increased procalcitonin (OR = 4.8, 2.034-11.31) or D-dimer (OR = 3.7, 1.74-7.89), and thrombocytopenia (OR = 6.23, 1.031-37.67) conveyed the highest odds for the adverse composite endpoint. Advanced age, male sex, cardiovascular comorbidities, acute cardiac or kidney injury, lymphocytopenia and D-dimer conferred an increased risk of in-hospital death. With respect to the treatment of the acute phase, therapy with steroids was associated with the adverse composite endpoint (OR = 3.61, 95% CI 1.934-6.73), but not with mortality. Conclusions: Advanced age, comorbidities, abnormal inflammatory and organ injury circulating biomarkers captured patients with an adverse clinical outcome. Clinical history and laboratory profile may then help identify patients with a higher risk of in-hospital mortality

Spatial Accessibility and Equity Analysis of Amazon Parcel Lockers Facilities

The onset of the COVID-19 pandemic has accelerated the growth of e-commerce and home 32 deliveries. Automated parcel lockers are a way to improve delivery efficiency, but despite their 33 rapid growth, little is known about their accessibility and equity impacts. Among e-commerce 34 players in the U.S., Amazon stands out by its large market share. This research studies the 35 location of Amazon lockers in Portland, Oregon utilizing highway, land use, employment, and 36 sociodemographic datasets. Geographical tools and cluster analysis are utilized to estimate 37 accessibility and equity metrics. Lockers tend to be located in mixed-use areas and can be 38 utilized by a large percentage of the population. However, the equity metrics indicate that the current distribution of lockers could be improved to reach traditionally underserved populations. Given the environmental and economic advantages of lockers, policymakers should encourage the expansion of this type of last mile solution to avoid market failures in areas that are currently underserved

Evidence from Urban Roads without Bicycle Lanes on the Impact of Bicycle Traffic on Passenger Car Travel Speeds

A concern raised by some motorists in relation to the presence of bicycles on urban roads without bicycle lanes, discussed in part of the traffic literature, is that cyclists will slow down motorized vehicles and therefore create congestion. This research answers this question: do bicycles reduce passenger car travel speeds on urban roads without bicycle lanes? To answer this question, a detailed comparative analysis of the travel speeds of passenger car (class two vehicles) on lower volume urban roads without bicycle lanes is presented. Speed distributions, the mean, and the 50th and 85th percentile speeds for two scenarios were examined: (i) a passenger car that was preceded by a bicycle and (ii) a passenger car that was preceded by another passenger car. Peak hour traffic and 24-h traffic speeds were analyzed using t-tests and confidence intervals. Although a few statistically significant differences between scenarios (i) and (ii) were found, the actual speed differences were generally in the order of 1 mph or less. Therefore, differences in class two (motorized passenger) vehicle speeds with and without cyclists were found to be negligible from a practical perspective. Bicycling is a vastly underutilized mode throughout most of the U.S.A., comprising just half of one percent of commuters throughout the nation (1) Given its potential for greater flexibility in route choice and lower costs for infrastructure and operation compared with transit, there is a substantial opportunity for cities to expand bicycling as a primary transportation mode. Congestion mitigation and environmental concerns from rising urban populations have been significant factors cited by communities as they push for greener transportation policies and travel modes. According to the Portland Bureau of Transportation, in 2017, 6.3% of commuters traveled by bicycle (2). The Portland Bike Plan has established a goal to increase that mode share to 25% by the year 2030 (3). With this mode shift toward bicycling, it is necessary to study the impacts these changes may have on the existing transportation network and motorized vehicles. In support of the Portland Bike Plan’s goal to reach a 25% bicycle mode share, the city authorities expect to add nearly 100 mi (161 km) of bikeways to the existing 385 mi (620 km), approximately 36% of which are currently shared-use roadways (2). Although it is generally favored to segregate bicyclists and motor vehicles, it is infeasible and often unnecessary to create such infrastructure on every road. For example, Danish bicycle design guidelines suggest that mixed traffic conditions are acceptable for roadways with speed limits less than approximately 35 km/h (22 mph) and average daily traffic (ADT) less than approximately 2,500 vehicles (4). Shared-use roads can be an economical solution to a growing demand for bicycle facilities. However, this sharing of space presents its own challenges in the contexts of safety and mobility. Several research studies have been conducted on vehicle–bicycle interactions, many of them focused on lateral positioning and passing behavior. Of particular interest, however, is the effect of bicycle traffic on motorized traffic speed, capacity, and flow. A general concern of motorists in relation to the presence of bicycles on roads without bicycle lanes is that they will impede motor vehicles because of their differing performance characteristics, which may serve to increase congestion and vehicle emissions—two consequences of urbanization that a larger bicycle mode share seeks to mitigate. Recent discussions based on a simulated traffic study have warned that traffic congestion and travel time delay will worsen as the bicycle mode share increases unless bicycle lanes are installed (5, 6). To the authors’ knowledge, there have not been any studies to date using empirical data of passenger cars on shared roads or roads without bicycle lanes that explore the validity of this claim. This paper seeks to expand the knowledge on vehicle–bicycle interactions by studying the impact of bicycles on the travel speed of passenger cars on roadways without bicycle lanes