From Tech Transfer Newsletter, Winter 2008
This document is found at www.techtransfer.berkeley.edu/newsletter/08-1/resources.php

Resources from the Transportation Library
Passing Lanes on Two-Lane Rural Roads

By Rita Evans, Reference Librarian, Institute of Transportation Studies Library

Super 2 Highways: Two-Lane Rural Highways with Passing Lanes

TTI Project Summary Report

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Design Guidelines for Passing Lanes on Two-Lane Roadways (Super 2)

Complete Report
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• Develops design guidelines that can be used to design periodic, short-term passing lanes (called Super 2 roadways in Texas). Addresses optimum passing lane length and spacing, shoulder width requirements, and optimum signing and pavement marking strategies. Such passing lanes improve traffic operations by breaking up platoons and by reducing delays caused by inadequate passing opportunities.

Methods for Increasing Passing Opportunities on Two-Lane Roads

AASHTO, 2004, pages 250-255.

• Describes passing lanes, turnouts, shoulder driving and shoulder use. More detailed information on these techniques is available in FHWA's informational 1987 guide Low Cost Methods for Improving Traffic Operations on Two-Lane Roads

Benefits and Design/Location Criteria for Passing Lanes

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Midwest Research Institute, Missouri DOT, 2004.

• Found that passing lanes improve percent time spent following by 10 percent to 31 percent and accident frequency is 12 percent to 24 percent lower than for conventional two-lane highway sections. Presents criteria to determine where passing lanes could provide level of service and safety benefits. Looks at five case studies from Missouri.

Incremental Improvements to Rural Two-Lane Highways

Mack-Blackwell Transportation Center, 2003.

• Focuses on three-lane alternate passing designs in Arkansas. Aspects examined include effects of passing lane length on speed, platooning and passing, and crash histories of transitions and passing lanes. Even though the passing lane segment volumes were higher than the state average, crash rates were lower than the statewide average crash rate on rural two-lane roads.

Review of the Effectiveness, Location, Design and Safety of Passing Lanes in Kansas

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Kansas State University and Kansas DOT, 1999.

• Evaluates the effectiveness of existing passing lanes in Kansas from an operational, safety, and public perception standpoint. Provides information for locating, planning, designing, constructing and signing passing lanes in a way that maximizes their safety and efficiency. Addresses the geometric elements relating to passing lanes, including lane and taper length and cross sections, and pavement marking and signing. Available statistics show a downward trend in crashes.

Interactive Highway Safety Design Model (IHSDM)

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Federal Highway Administration, 2007.

• IHSDM checks existing or proposed two-lane rural highway designs against relevant design policy values and estimates expected safety and operational performance. Highway project managers, designers, traffic reviewers and engineering consulting firms can download the 2007 release free of charge; free technical support is also available. Includes five modules: Crash Prediction, Design Consistency, Intersection Review, Policy Review, and Traffic Analysis.

Making Two-Lane Roads Safer

by Raymond A. Krammes and Carl Hayden
Public Roads, January/February 2003.
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• Describes the Crash Prediction and Policy Review modules of the Interactive Highway Safety Design Model (IHSDM).

A Comparison and Evaluation of the Geometric Design Practices with Passing Lanes, Wide-Paved Shoulders and Extra-Wide Two-lane Highways in Canada and Germany

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International Symposium on Highway Geometric Design Practices, 1998. TRB E-Circular 003.

• Discusses operational experiences in terms of overtaking rates, speed-volume relationships, platooning, level-of-service, accident rates and driver attitudes. Finds that passing lanes, wide-paved shoulders and extra-wide two-lane highways increase the level of service and decrease the accident rate compared to convential two-lane roads.

Effective Use of Passing Lanes on Two-Lane Highways

Harwood, Hoban, Warren. Transportation Research Record 1195. 1988, pages 79-91.

• Provides guidelines for effectively locating, designing, signing, and marking passing lanes to improve traffic operations. Presents a procedure for estimating the operational effectiveness of passing lanes in terms of improved service. Finds that such passing lanes  are effective in reducing accidents on two-lane highways.

Design Guide for Auxiliary Passing Lanes on Rural Two-Lane Highways

Kaub, Berg. Transportation Research Record 1195. 1988, pages 79-91.

• Identifies conditions under which the construction of an auxiliary passing lane on two-lane rural highways is economically justified. Benefit-cost analysis was applied to determine the average daily traffic (ADT) levels at which an auxiliary passing lane would be economically justified as a function of section length, percent passing zones available, cost per conflict, construction cost, and discount rate.

Application of European 2+1 Roadway Designs

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NCHRP Research Results Digest No. 275, Transportation Research Board, April 2003, 31 pages.

• Describes how using a continuous three-lane cross section with alternating passing lanes, known in Europe as 2+1 road design, can substantially improve operational level of service without increasing capacity. The 2+1 is recommended for traffic flow rates of up to 1200 veh/h in one direction. Use of 2+1 design is appropriate for roads with a substantial percentage of heavy vehicle traffic and it can be used in level or rolling terrain. The digest includes a summary of European practice and recommendations for use in the U.S.

About the UC Berkeley Transportation Library

Most of the items listed in this article are available from the UC Berkeley Transportation Library. Visit the Library homepage for more information about the library or to request access.

• Employees of California public sector transportation agencies at the local, state, and regional levels, including federal agencies located in California, are eligible to request anything in the transportation library's catalog for free. The library will even provide up to 50 pages of photocopies of articles from journals, trade magazines, or conference reports, or scan and e-mail the requested material.

What People Have to Say About the Transportation Library

"I have a science background, so I was searching journals for information when I found a reference to the Harmer Davis Library. The librarian pulled a lot of stuff and e-mailed it, plus sent copies of material that wasn't available online. We're a rural county and we're far away. It saved us the time and expense of my driving down and hunting for the information myself." Vickie Smith-Becker, Analyst, Calaveras County DPW

"I'm on a committee tasked to look five-plus years into the future and to explore alternative fuel/rolling stock. The Town of Mammoth Lakes purchased six new trolleys and six new cutaway buses last year. All gasoline powered. The ski area (Mammoth Mountain) has large diesel buses—they burn five percent bio. We've started a vehicle replacement fund, and are looking at getting the first new piece of rolling stock around 2012. What that may be is undetermined at this point, and as we've learned, can or will change almost every year as we see hybrid, hydrogen, CNG, etc. come about. The information Rita has provided me has been great." Scott Campbell, Assistant Airport Manager, Mammoth Yosemite Airport.

For more about how the Transportation Library makes research easier for transportation professionals in California, read this article.

Next time you're doing research, make the transportation library your first stop. Then, send them your success story.

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