Office of Operations
21st Century Operations Using 21st Century Technologies

Safety Implications of Managed Lane Cross Sectional Elements

Printable Version [PDF, 900 KB]
You may need the Adobe® Reader® to view the PDFs on this page.
Contact Information: Operations Feedback at OperationsFeedback@dot.gov

Publication No. FHWA-HOP-16-076
December 2016

United States Department of Transportation Federal Highway Administration logo

U.S. Department of Transportation
Federal Highway Administration
Office of Operations (HOP)
1200 New Jersey Avenue, SE
Washington, DC 20590

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

The Federal Highway Administration provides high quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

Technical Report Documentation Page

1. Report No.
FHWA-HOP-16-076
2. Government Accession No. 3. Recipient's Catalog No.
4. Title and Subtitle
Safety Implications of Managed Lane Cross Sectional Elements
5. Report Date
December 2016
6. Performing Organization Code
 
7. Author(s)
Kay Fitzpatrick and Raul Avelar (Texas A&M Transportation Institute)
8. Performing Organization Report No.
 
9. Performing Organization Name and Address
Battelle
505 King Avenue
Columbus, OH 43201
Texas A&M Transportation Institute
State Headquarters Research Building
2935 Research Parkway
Texas A&M University Research Park
3135 TAMU
College Station, TX 77843-3135
10. Work Unit No. (TRAIS)
 
11. Contract or Grant No.
Contract No. DTFH61-12-D-00046;
Task Order No. T-5012
12. Sponsoring Agency Name and Address

U.S. Department of Transportation
Federal Highway Administration Office of Operations
1200 New Jersey Avenue, SE
Washington, D.C. 20590
13. Type of Report and Period Covered
Technical Report
May 2016-December 2016
14. Sponsoring Agency Code
FHWA-HOP
15. Supplementary Notes
Greg Jones, FHWA Task Manager
16. Abstract

The objective of this project was to investigate the relationship between crashes and buffer-separated manage lane dimensions. The results from several previous research studies have demonstrated that reductions in freeway lane width or shoulder width are associated with more crashes. A wider managed lane envelope widths (i.e., left shoulder, managed lane, and buffer width combined) are also associated with fewer freeway crashes for both all severity levels and fatal and injury severity levels. Wider envelopes are associated a reduction of 2.8 percent (in Texas) or 2.0 percent (in California) in total freeway crashes (all severities) for each additional foot of envelope width. In California, wider envelopes are associated with a reduction of 4.4 percent in managed lane-related crashes (fatal and injury severity levels) for each additional foot of envelope width. The analysis was conducted on non-weaving managed lane segments that included a single managed lane separated from the general purpose lanes with a flush buffer area. The dataset included crashes on 128.0 miles in California (all 128.0 miles with flush buffers) and 60.4 miles in Texas (41.7 miles with pylon buffers and 18.7 miles with flush buffers). The California sites included freeways with three or four general-purpose lanes while the Texas freeways had three to five general-purpose lanes.

17. Key Words
Managed lane, safety, crashes, cross-section, buffer width, shoulder width
18. Distribution Statement
No restrictions.
19. Security Classif.
(of this report)

Unclassified
20. Security Classif.
(of this page)

Unclassified
21. No. of Pages
52
22. Price

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES

LIST OF ABBREVIATIONS

AADT
Annual average daily traffic
AADTHV
Annual average daily traffic for the managed lane
AADTMainL
Annual average daily traffic for the general-purpose lanes
AASHTO
American Association of State Highway and Transportation Officials
Avg
Average
Buf_Type
Analysis variable; buffer type between managed lane and general-purpose freeway lanes – either pylons or flush
Buf_W
Analysis variable; buffer width
Dir
Direction
DOT
Department of transportation
EB
Eastbound
F
Flush buffer
FHWA
Federal Highway Administration
ft
Foot or feet
GP_Adj_W
Analysis variable; general-purpose lanes, width of lane adjacent to the managed lane
GP_All_Ln_W
Analysis variable; general-purpose lanes, width of all general-purpose lanes
GP_Avg_Ln_W
Analysis variable; general-purpose lanes, average lane width
GP_Ent
Analysis variable; general-purpose lanes, number of entrance ramps within the segment
GP_Exit
Analysis variable; general-purpose lanes, number of exit ramps within the segment
GP_NumLn
Analysis variable; general-purpose lanes, number of general-purpose lanes that are not barrier separated and are moving in same direction
GP_R_Shld_W
Analysis variable; general-purpose lanes, right shoulder width
GP_Trvl_W
Analysis variable; general-purpose lanes, travel width for general-purpose lanes, determined as number of lanes multiplied by average lane width
GP_Weave
Analysis variable; general-purpose lanes, number of weaving areas within the segment
HOT
High-occupancy toll
HOV
High-occupancy vehicle
HSIS
Highway Safety Information System
HV
Abbreviation used for HOV or managed lanes in analysis
Hwy
Highway
m
Meter
Max
Maximum
mi
Mile
Min
Minimum
ML
Managed lane
MLB
Managed lane or buffer related crashes
ML_L_Shld_W
Analysis variable; managed lane, left shoulder width
ML_Ln_W
Analysis variable; managed lane, lane width
ML_Env
Analysis variable; managed lane envelope which is the sum of left shoulder width, lane width, and buffer width
MRI
Midwest Research Institute
MUL
Managed use lane
NB
Northbound
NCHRP
National Cooperative Highway Research Program
NW Length
Sum of the lengths for non-weaving segments within the corridor
OLCR
Optimal lane changing region
P
Pylons present within buffer area
PSL
Posted speed limit
SB
Southbound
T_Trvl_W
Analysis variable; total travel width
veh
Vehicle
WB
Westbound
yr
Year
Office of Operations