2020 TRB Annual Meeting

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Join us at the 2020 TRB Annual Meeting in Washington, DC January 12-16

(Note, on Dec 10 TRB assigned a new comittee structure. Access Management Committee (ACP60) is now under the Operations Section (ACP00).

Sunday  1:30 PM-4:30 PM

Workshop 1074

Applying Your Multimodal Access Management Toolbox
Marc Butorac, Kittelson & Associates, Inc. (KAI), presiding
Workshop
Operations and Traffic Management, Design
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Monday  10:15 AM-12:00 PM

Poster Session 1223

Access Management 2020
Poster
Operations and Traffic Management 
(see descriptions at end)

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Monday  7:30 PM-9:30 PM

Intersections, AHB65(1), Joint Subcommittee of AHB65, AFB10, AHB70, ANB20
Gil Chlewicki, Advanced Transportation Solutions, LLC, presiding
Jonathan Soika, VHB, presiding
Design, Operations and Traffic Management, Safety and Human Factors
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Tuesday  12:00 PM-1:30 PM

National Conference on Access Management Subcommittee, AHB70(1)
Lionel Lucien, Massachusetts Department of Transportation, presiding
By Invitation
Operations and Traffic Management

Tuesday  1:30 PM-3:15 PM

Access Management Research Subcommittee, AHB70(2)
Christopher Cunningham, North Carolina State University, presiding
Eric Fitzsimmons, Kansas State University, presiding
Operations and Traffic Management
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Tuesday  3:45 PM-5:30 PM

Access Management Outreach Subcommittee, AHB70(3)
Kristine Connolly, Kittelson & Associates, Inc. (KAI), presiding
Joy Davis, Institute for Transportation Research and Education, presiding
Operations and Traffic Management
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Wednesday  8:00 AM-12:00 PM

Access Management Committee
Grant Schultz, Brigham Young University, presiding
Operations and Traffic Management
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Poster session 1213Monday 10:15 AM-12:00 PM

Effect of Driveway Land-Use Type on Safety Performance for Two-Lane Rural State Highways and County Roads

Meghna Chakraborty, Michigan State University
Timothy Gates, Michigan State University

Rural roads are a critical component of transportation network in the United States, including Michigan, where county roads comprise of a majority of the state’s roadway mileage. The rates of fatal crashes on rural highways are substantially higher than that on urban roads. Previous research has investigated the safety impacts of driveway density, but little has captured the effects of various driveway land-use categories on rural roadway safety performance, particularly for county roadways. This study analyzes the safety impacts of various classifications of driveway land utilization on rural two-lane state and county roads in Michigan. Non-animal segment crashes from 2011 to 2015 were analyzed along with roadway data for greater than 5,556 miles of state highways and 5,890 miles of paved county segments from across Michigan. To account for the unobserved heterogeneity associated with varied county design standards, mixed-effects negative binomial regression models with a county-specific random effect were utilized. Separate models were developed for state highways and paved county roads. The results indicated that commercial driveways possess a stronger effect on crash occurrence than other driveway land use types, including residential and industrial driveways. The effect of driveway density on crash frequency was also found to be stronger on state highways compared to the county roads. This study contributes to the limited body of knowledge regarding the relationship between traffic safety and driveway land use for rural roadway segments, particularly for county roads, which typically possess design and travel characteristics that are considerably different from those of state highways. 

Safety Performance of Rural Offset T Intersections

Anthony Ingle, Michigan State University
Timothy Gates, Michigan State University

Offset T intersections represent a special case where two three-leg intersections adjoin the major road from opposite directions within a minimal separation distance. The operational and safety characteristics of these two intersections are inter-dependent. In rural areas, the preponderance of offset T intersections occur where section line minor roads intersect township line roads and primary arterials often at nearly perpendicular angles. Safety performance functions are developed using negative binomial models to predict the crash frequency among a sample of 113 offset T intersections and 112 four-leg cross intersections along rural Michigan highways. Through a cross sectional analysis, several crash modification factors for the conversion of an offset T intersection to a four-leg cross intersection are determined. A reduction of in total crash frequency of up to 34 percent is expected when converting and offset T intersection into a four-leg intersection. Fatal and injury crash frequencies are expected to reduce by 24 percent, while property damage only crash frequencies are expected to reduce by 16 percent. For low minor road traffic volumes (less than 15 percent of the total intersection entering traffic) converting an offset T intersection to a four-leg intersection can reduce angle crashes by 51 percent. However, offset T intersections are much more effective at reducing angle crashes for moderate to high minor road traffic volumes. Rear-end crash types can be reduced by 46 percent by converting an offset T intersection to a four-leg intersection. This study will help safety engineers to prioritize the improvement of rural un-signalized intersections. 

Poster Session 1221 10:15 AM-12:00 PM

Driveway Access Spacing Considerations for Rural Highways with High Truck Volumes

Marcus Brewer, Texas A&M Transportation Institute
Kay Fitzpatrick, Texas A&M Transportation Institute
James Cline, Texas A&M Transportation Institute

Increased traffic and heavy truck percentages associated with energy exploration in west Texas have placed unprecedented demands on the region’s highway network as well as driveway access to and from that network. Access management principles have proven to be effective in improving operations and safety in numerous locations, but many of those locations have been in urban or suburban locations where land uses and traffic patterns are different from those typically found in rural west Texas, so guidelines for driveway spacing and other access management treatments in rural, high-speed areas are not as commonplace. This paper describes the study of a corridor with high volumes, high truck percentages, high speeds, high turning volumes, and high demand for access. The study team reviewed the applicable guidelines and policies for driveway spacing in Texas, as well as relevant findings from other guidelines and research, to develop a set of recommended driveway spacing values for cars and for trucks on high-speed rural roads. 

 

Poster Session 1691 Wednesday 8:00 AM - 9:45 AM

Safety Performance of Autonomous Vehicles on an Urban Arterial in Proximity of a Driveway

Seyedeh Maryam Mousavi, Texas A&M University, College Station
Dominique Lord, Texas A&M University, College Station
Seyed Reza Mousavi, Shiraz University
Maryam Shirinzad, Texas A&M University, College Station
Maryam Shirinzad, Texas A&M University, College Station

Urban traffic network has been growing as an integral part of cities. Urban arterials, as the backbone of the urban traffic network, are characterized by closely spaces driveways and carry a high traffic volume per day. The literature consistently reported that there is a positive relationship between driveway density and crash rate. Therefore, managing driveways, which usually work as three-legged unsignalized intersections, located along urban arterials is crucial, especially under high traffic demand, to improve both safety and operation. However, due to the cost and space limitation, conventional methods are impractical and, therefore, new solutions should be implemented. Autonomous Vehicles (AVs), as a multidisciplinary technology, have been the focus as a replacement for human-driven vehicles to improve both traffic safety and operation. In this study, the effect of AVs on the safety of an urban arterial in the proximity of an unsignalized intersection was evaluated. A microsimulation model was used to develop an urban network with an unsignalized access point under various traffic congestion levels for both conventional vehicles and AVs. Afterward, the frequency and distribution of the conflicts for conventional vehicles and AVs were compared. The results indicated that AVs can enhance safety significantly compared to the conventional vehicles in proximity of an access point, especially under congested traffic situations. However, providing an exclusive lane on the arterial for the driveway vehicles to merge to the arterial promotes safety and operation of the network.

 

Author: 
AHB70