J L Gattis

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.

School Bus Design Vehicle Dimensions

Research was conducted to generate design vehicle characteristics for large or full-size school buses. Characteristics that were measured include length, width, overhangs, and the turning radius and path for 90° and 180°turns. The researchers observed the paths of the inner rear tire, the outer front corner, the outer front tire, and the outer rear corner. The paths observed in the field were contrasted to those generated by computer-aided design software. The path of the outer rear corner was found to be a significant consideration during the initial part of a turn. The researchers recommended adoption of a more intuitive terminology to describe the various turning paths.

Influences of Cross-Sectional Design Elements at Urban Arterial Driveway Locations

This paper presents a study on the influences of select cross-sectional design elements—specifically median configurations and bicycle lanes—and their impact on crash severity and type as well as the associated driver gap acceptance for turning maneuvers at midblock driveway locations on urban arterials. The primary goal of this research is to better understand how median and bicycle lane configurations can influence safety and operations at driveway locations. The authors used crash data, traffic data, and roadway information from driveway locations in Oregon, Arkansas, and Oklahoma. The data were supplemented with digital videos from field studies of the sites. These traffic videos helped to better understand how road features and traffic influenced driver behavior at selected urban arterial driveway locations. Gap acceptance studies were conducted to determine critical gaps for driveway locations at arterial roads with and without bicycle lanes. Four critical gap analysis methods were evaluated to estimate driveway operations and noted potential procedural biases associated with two of the techniques. The paper describes these field studies and summarizes how gap acceptance varied at different arterial driveway locations. Simulation analysis in CORSIM (Version 6.3) examined the influence of median type, traffic volume, and access density on traffic operational performance.