Offer Grembek

University of California, Berkeley | UCB · Department of Civil and Environmental Engineering

This chapter describes the results of a short-term analysis of highway crashes in California during the first year of the COVID-19 pandemic. The pandemic has had an unexpected and abrupt influence on the demand for mobility. The effect of this was a drastic reduction in the level of activity on the roads. This level of activity defines the exposure...

Autonomous vehicles (AVs) are promoted as a technology that will create a future with effortless driving and virtually no traffic accidents. AV companies claim that, when fully developed, the technology will eliminate 94% of all accidents that are caused by human error. Indeed, these AVs will likely avoid the large number of crashes caused by impai...

The operational reality that dominates organizations can inhibit their ability to document recurring work processes, which is instrumental in defining work responsibilities, incorporating quality assurance, evaluating lead time, eliminating inefficiencies, and developing workforce training requirements. The authors describe the application of proce...

Autonomous vehicles (AVs) are promoted as a technology that will create a future with effortless driving and virtually no traffic accidents. AV companies claim that, when fully developed, the technology will eliminate 94\% of all accidents that are caused by human error. These AVs will likely avoid the large number of crashes caused by impaired, di...

Intersections are hazardous places. Threats arise from interactions among pedestrians, bicycles and vehicles, more complicated vehicle trajectories in the absence of lane markings, phases that prevent determining who has the right of way, invisible vehicle approaches, vehicle obstructions, and illegal movements. These challenges are not fully addre...

Count expansion methods are a useful tool for creating long-term pedestrian or cyclist volume estimates from short-term counts for safety analysis or planning purposes. Expansion factors can be developed based on the trends from automated counters set up for long periods of time. Evidence has shown that the activity patterns can vary between sites...

For this study, we developed one of the first statewide pedestrian exposure models, using log-linear regression to estimate annual pedestrian crossing volumes at intersections on the California State Highway System. We compiled a database of more than 1,200 count locations, one of the largest ever used to create a pedestrian volume mode. We initial...

Bicycle level of service (LOS) measures are essential tools for transportation agencies to monitor and prioritize improvements to infrastructure for cyclists. While it is apparent that different types of cyclists have varying preferences for the facilities on which they ride, in current research and practice, measures are used that are either insuf...

Complex movement patterns of pedestrian traffic, ranging from uni-directional to multi-directional flows, are frequently observed in major public infrastructure such as transport hubs. These multi-directional movements can result in increased number of conflicts thereby influencing the mobility and safety of pedestrian facilities. Therefore, empiri...

Expansion factors based on the trends in long-term count data are useful tools for estimating daily, weekly, or annual volumes from short-term counts, but it is unclear how to differentiate locations by activity pattern. This paper compares two approaches to developing factor groups for hour-to-week pedestrian count expansion factors. The land use...

Intersections are hazardous places. Threats arise from interactions among pedestrians, bicycles and vehicles, more complicated vehicle trajectories in the absence of lane markings, phases that prevent knowing who has the right of way, invisible vehicle approaches, vehicle obstructions, and illegal movements. These challenges are not fully addressed...

This paper presents a method to assess the safety of uncontrolled intersections considering two major properties of traffic conflicts-conflict probability and severity. This method assesses both the safety level of the entire intersection in addition to the distribution of safety within it. Intersections are modeled by a two-dimensional Cartesian c...

In this paper, the non-motorized traffic safety concerns in and around three university campuses are evaluated by comparing police-reported crash data with traffic safety information sourced from the campus communities themselves. The crowdsourced traffic safety data comprise of both self-reported crashes as well as perceived hazardous locations. T...

Decision makers are encouraged to consider multiple objectives (such as traffic efficiency, safety, and environment) together to make decisions. Although there are methods to evaluate each objective respectively, there are few reports or research papers showing how to incorporate these objectives and put it in practice. Thus, this study aims to dev...

Objectives: To identify the characteristics related to crash and victim, as well as the after-effects/disabilities and consequences arising from traffic crashes occurring in the city of Rio Branco - Acre. Methods: This is an analytical descriptive cross-sectional study conducted in the City of Rio Branco - Acre. The study population consisted of...

Network screening techniques are widely used by state agencies to identify locations with high collision concentration, also referred to as hot spots. However, most of the research in this regard has focused on identifying highway segments that are of concern to automobile collisions. In comparison, pedestrian hot spot detection has typically focus...

The objective of this work is to identify characteristics of different metrics of exposure for quantifying multi-modal travel injury risk. First, a discussion on the use of time-based and trip-based metrics for road user exposure to injury risk, considering multiple travel modes, is presented. The main difference between a time-based and trip-based...

Information about pedestrian infrastructure and volume is indispensable to monitoring, evaluating, and improving the environment for comfortable and safe walking. However, determining and organizing the various types of data in a way that is easy to update and analyze can present challenges. This study designed and developed a relational database f...

The multimodal transportation network includes a mix of inherently different modes. In addition to differences in price, range, and comfort of travel, these modes differ in mass and velocity, which correspond to different orders of magnitude in the kinetic energy carried. This discrepancy in kinetic energy affects both the level of protection of ea...

Background: In recent years, there has been a rush to pass laws to regulate or ban the use of electronic devices while driving, a behavior that is known to reduce driver attention and performance. These laws vary, targeting handheld cell phone use, text messaging, or certain types of drivers (e.g., commercial or teen). Methods: A natural experime...

Problem, research strategy, and findings: College campuses are multimodal settings with very high levels of walking and biking in conjunction with high levels of vehicular traffic, which increases risks for bicyclists and pedestrians. In this study, we examine crash data (both police reported and self-reported) and urban form data from three U.S. c...

Prominent pedestrian trip attractors, such as college campuses and major urban parks, are often surrounded by roadways with high volumes of motor vehicle traffic. Although many pedestrians cross busy boundary roadways, relatively little is known about the pedestrian crash risk along these types of facilities. This study quantifies pedestrian crash...

Two safety management tools have recently been developed for the California Department of Transportation (Caltrans). One is the continuous risk profile (CRP) approach, which is a network screening procedure, and the other is the California Safety Analyst (CASA), a web-based application designed to assist state safety engineers in conducting safety...

The paper deals with the estimation of pedestrian risk exposure in urban areas. The approach proposed is based, on the one hand, on a spatial analysis technique called Space Syntax that characterizes the street integration - how streets are connected to each other - which gives rise to a natural movement of persons, and on the other hand, on land-u...

Pedestrian exposure is a necessary component for a meaningful evaluation of pedestrian safety. The Space Syntax approach has a track record of accurate prediction of pedestrian activity by estimating the physical street connectivity in urban environments. However, for some environments, the performance of Space Syntax is limited and cannot be used...

Background: Rapid deployment of motor vehicles globally has contributed to increased economic development. However, with benefits of motorization have come fatalities and injuries: more than 1.2 million fatalities and 50 million injuries in 2009; about half are vulnerable road userspedestrians, cyclists, and motorcyclists. The World Bank and the Wo...

L'article présente des travaux en cours sur l'analyse des déplacements de piétons autour du campus de l'Université de Californie à Berkeley et la prédiction du nombre de passants. La finalité de cette recherche est l'estimation de l'exposition des piétons au risque de collision avec des véhicules. Il s'agit d'un indicateur permettant au gestionnair...

The perceptibility of a safety system is defined as the extent to which the system can be perceived by the senses or the mind. A web-based, pairwise comparison survey, was conducted to eval-uate the perceptibility of fifteen safety systems ranging from traffic safety systems to consumer safety. The analytic hierarchy process was applied to estimate...

Although it is generally believed that people drive less carefully when their vehicles are equipped with new protection systems, the possible impact of such behavior on fatalities has never before been quantified. A meta-study across a diverse set of injury protection systems strongly suggests that users do adapt to new protection systems in a way...

Methods for identifying sites with potential for preventing traffic fatalities and injuries have been developed for vehicle-vehicle collisions. This study was funded by the California Department of Transportation (Caltrans) to develop methods for identifying sites where there is potential for significant reductions in pedestrian and bicyclist injur...