Jerome Gluck

Safety of U-Turns at Unsignalized Median Openings: Some Research Findings

Many state and local transportation agencies install nontraversable medians on multilane highways to improve safety and travel times and to manage local access better. While nontraversable medians restrict direct left-turn access to and from adjacent developments, traffic destined for these locations must use alternate routes, some of which may involve making U-turns at nearby median openings-a movement often referred to as an indirect left turn. Until recently, the safety effects of increased U-turn volumes have been largely unknown. NCHRP Project 17-21, Safety of U-Turns at Unsignalized Median Openings, documented the safety performance and operational effects of U-turns at median openings. This paper presents the key findings from that research. It presents a summary of key literature and current highway agency practice related to median openings, a detailed classification scheme for median openings, and a summary of the results of comprehensive field studies. The research results indicate that access ...

State of the Practice in Highway Access Management

This synthesis reports how various agencies have acted on the various components of an access management program, what have been barriers to action, and how new efforts might improve implementation of access management strategies. Primary focus areas considered are legal and legislative bases, contents of policies and programs, implementation aspects, reported effectiveness of program implementation, and profiles of contemporary practice. This synthesis reports on the state of the practice with respect to planning, highway design, development review and permitting, and other focus areas where access management is typically incorporated. The emphasis is placed on states, but counties, municipalities, and metropolitan planning organizations are also considered. The synthesis includes a comprehensive review of existing access management-related literature. This was supplemented by an online survey questionnaire distributed to key staff with access management responsibilities identified by state departments of transportation, as well as various participating metropolitan planning organizations, counties, and municipalities. Although 45 of 50 states initially responded to the survey, 5 additional states later provided survey responses, raising the response rate to 100%. In addition, profiles of contemporary access management practices, highlighting key aspects of how transportation agencies develop and administer their access management programs are presented.

Development of Left-Turn Lane Warrants for Unsignalized Intersections

Left-turn movements at intersections, including driveways—especially movements that are made from lanes that are shared with through traffic—cause delays and adversely affect safety. Although some left-turn warrants have been updated, many agencies still use research performed by M. D. Harmelink in the mid-1960s. Most states use procedures that are based on Harmelinks work, but several limitations have been identified. Economic analysis can provide a useful method for combining traffic operations and safety benefits of left-turn lanes to identify situations in which left-turn lanes either are or are not justified economically. This project used a benefit–cost approach to determine when a left-turn lane would be justified. The steps included simulation to determine delay savings from installing a left-turn lane, crash costs and crash reduction savings determined from safety performance functions and crash modification factors available in the Highway Safety Manual, and construction costs. Left-turn lane warrants were developed for rural two-lane highways, rural four-lane highways, and urban and suburban roadways. In addition, warrants for bypass lanes were developed for rural two-lane highways.

Access Management: The Challenge of Retrofit Theory Versus Reality

This paper discusses issues encountered in developing a retrofit project for a roadway in a densely developed, commercialized area. The project was initiated, directed, and funded by the New York State Department of Transportation (NYSDOT). Numerous major shopping centers and a high volume of through traffic produce congestion and affect safety. NY-27, also known as Sunrise Highway, is a principal arterial in suburban Long Island. The conditions along NY-27 reflect what happens when development approvals are granted by local land use agencies without sufficient consideration of whether the transportation system can accommodate the associated traffic. NYSDOT, in this case, was put in the position of attempting to implement a retrofit project to mitigate the traffic and safety conditions. The proximity of shopping center driveways to each other and to nearby intersections results in weaving movements and heavy turning-movement volumes that block the through travel lanes and cause overlapping conflicts. The significant traffic congestion and high accident rate reflect the problems caused by inadequate access spacing and need for improved access management. The improvement options identified represented a wide range of access management strategies and configurations. The options were screened and modified to reflect community desires and business concerns. This paper reviews operational and safety problems, identifies a theoretical access configuration along the NY-27 corridor that could mitigate these problems, and reviews the alternative that was approved and is being progressed. The approved alternative reflects real-world considerations that affect a retrofit project.

Access Management at a High-Volume Interchange

Alternatives for improving operations and safety at the complex urban Highbridge Interchange of the Cross Bronx Expressway (Interstate 95) and the Major Deegan Expressway (Interstate 87) in New York City are presented. These alternatives were developed as part of the Bronx Arterial Needs Major Investment Study (BAN MIS) that is being performed for the New York State Department of Transportation. The unusually high levels of congestion on Interstate 95 and Interstate 87 required a high level of analysis and alternatives development for this location. This interchange experiences high levels of delay and accident frequency for several reasons. The interchange incorporates two of the most heavily used Interstate highways in the city, and both of these have a high volume of trucks. It includes or is adjacent to other heavily used facilities, including park-ways, other expressways, and high-volume local arterials and the George Washington Bridge (a 14-lane facility). Finally, it is sited in a part of the western Bronx and northern Manhattan of New York City that is severely constrained by adjacent land uses, severe grades, and elevation changes. The BAN MIS is exploring a wide range of strategies in the vicinity of Highbridge Interchange to improve traffic operations and safety. Strategies applied basic principles of access management to reduce conflicts and eliminate weaving, to separate through from local movements, and to maintain a hierarchy of roads by function. These principles are applicable to other interchange projects to help in developing alternatives for improving traffic operations and safety.

EVALUATION OF HIGH-OCCUPANCY-VEHICLE LANES ON LONG ISLAND EXPRESSWAY

New York States first suburban high-occupancy-vehicle (HOV) lanes were opened in May 1994 along a 19.3-km (12-mi) stretch of the Long Island Expressway (LIE), I-495 in western Suffolk County, a major suburb of metropolitan New York City. As with some other HOV facilities across the country, the implementation of HOV lanes on Long Island remains controversial. Nevertheless, HOV lanes continue to have an important role in subsequent plans to manage congestion on the LIE. In May 1991 the New York State Department of Transportation formed the LIE/HOV task force to provide advisory opinions on key HOV issues. The task force, comprising private-sector and government representatives, recommended among its numerous findings that the New York State Department of Transportation establish a comprehensive HOV monitoring program to provide up-to-date information to the media and concerned citizens, as well as help fine-tune operational and marketing elements associated with HOV lane usage and to provide firsthand inf...

Considering and Applying Driveway Design for All Users

NCHRP Project 15-35, Geometric Design of Driveways, was initiated to help address the lack of comprehensive research and national design guidance for the design of driveway connections to roadways. The research initiated with this project included an extensive literature review, a survey of state agencies and contacts with interest groups, and fieldwork to measure traffic attributes. The project produced two publications: a research report on the NCHRP website and NCHRP Report 659: Guide for the Geometric Design of Driveways. This paper considers the following topics: (a) What design issues were identified? Current design practices may not adequately consider the range of all driveway users: bicyclists, motorists, and pedestrians. The paper discusses the vulnerability of various users on the basis of historical crash data. (b) What user attributes were found? The research produced information about the driveway grades at which the undersides of vehicles may drag and the speeds at which vehicles on urban arterials entered commercial driveways having radii ranging from 13 to 20 ft. (c) What design practices were recommended? The guide presents a number of design practices to better meet the needs of all users. This paper provides useful information for design consultants and local government professionals.

Multimodal Driveway Design

Driveways are the link between public roadways and the abutting activities that they serve. Driveways serve a wide range of activities in a variety of contexts. Driveway design guidelines have traditionally focused on accommodating motor vehicles, but in recent years, growing emphasis has been placed on a broader range of issues, such as better managing access and accommodating all modes, including pedestrians and bicyclists. How well driveways are designed affects the safety and mobility of not only motorists but also bicyclists and pedestrians. This paper draws from research performed for NCHRP Project 15–35, Geometric Design of Driveways. It discusses multimodal driveway design considerations and provides design guidelines that recognize the needs of pedestrians (including those with disabilities and transit users) and bicyclists.

Guide for the Geometric Design of Driveways

This report presents guidelines that will be of use to state departments of transportation, local governments, and consultants for the geometric design of driveways. It contains driveway-related terms and definitions, basic geometric controls, a summary of access spacing principles, and detailed discussions of various geometric design elements. The objective of the research was to develop recommendations for the geometric design of driveways that consider standard engineering practice and accessibility needs and provide for safe and efficient travel by motorists, pedestrians, and bicyclists on the affected roadway.

Overview of the Draft Roadway Access Management Guidelines for the Port Authority of New York and New Jersey

This paper provides an overview of the efforts by the Port Authority of New York and New Jersey (port authority) to develop and implement roadway access management guidelines for its airports and ports. The paper first summarizes the process used, including extensive intra-agency coordination, to develop and refine roadway access management guidelines tailored for port authority facilities. The paper then provides an overview of the draft guidelines recommended for each primary guidance area (e.g., traffic signal spacing and unsignalized driveway spacing). In many cases, the guidelines formalize the practices already used so that access management may be applied more consistently. The draft guidelines are under review by management in the port authoritys Engineering and Architecture Design Division. Administrative aspects, such as the variance procedure and language related to intra-agency coordination, are a primary focus. The guidelines include an access classification system with associated design criteria tailored to the specific functions of the agencys roadway facilities.