Safety of U-Turns at Unsignalized Median Openings (2004) / Chapter Skim
Currently Skimming:
Appendix B - Summary of Survey Responses From State and Local Highway Agencies
Appendix B - Summary of Survey Responses From State and Local Highway Agencies
Pages 90-105
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 90... ...
The responses indicate that about half of the responding agencies have formal policies concerning median opening location and about half have guidelines or informal policies. Table B-4 presents a list of the factors considered by highway agencies in determining the location of median openings.
|
From page 91... ...
Of the five county agencies that TABLE B-1 Response rate for the highway agency survey Agency type Number of questionnaires mailed Number of responses received Response rate (%) State agencies 50 35 70.0 Local agencies 109 30 27.6 Total 159 65 40.9 TABLE B-2 List of highway agencies that responded to survey State highway agencies Local highway agencies Alabama City of Mobile, AL Alaska Borough of Matanuska-Susitna, AK Arizona City of El Cajon, CA California City of San Diego, CA Connecticut City of Loveland, CO Florida City of Albany, GA Georgia City of Peoria, IL Idaho City of Ann Arbor, MI Illinois City of Kansas City, MO Iowa City of Springfield, MO Kansas City of Henderson, NV Louisiana City of Concord, NH Massachusetts City of Newark, NJ Michigan City of Bismarck, ND Mississippi City of Fargo, ND Missouri City of Columbus, OH Nebraska City of Norman, OK Nevada City of Charleston, SC New Hampshire City of Nashville, TN New Mexico City of Houston, TX New York City of St.
|
From page 92... ...
10 (17.9) Total number of agencies responding 31 25 56 Factors considered State agencies Local agencies Total Proximity to other median openings 15 11 26 Traffic volumes (particularly minor-road volumes)
|
From page 93... ...
This county stated that they use the access management policy of their state DOT. Question 4 -- Location of Unsignalized Median Openings Question 4 asked highway agencies about their policies for location of unsignalized median openings.
|
From page 94... ...
. Question 6 -- Use of Indirect Left-Turn Treatments Question 6 asked highway agencies about their use of indirect left-turn treatments.
|
From page 95... ...
59 (96.70) 61 TABLE B-9 Local agency policies on minimum median opening spacing TABLE B-10 Formal policies on location of unsignalized median openings TABLE B-11 Minimum sight distance (ft)
|
From page 96... ...
However, in larger metropolitan areas, a traversable TWLTL may be used. TABLE B-14 Type of policy used for geometric design of median openings TABLE B-15 Policy on the use of raised medians versus continuous two-way left-turn lanes Policy used for geometric design of median openings State agencies Local agencies Total AASHTO policy 19 (67.9)
|
From page 97... ...
Table B-16 presents the number and percentage of the state and local agencies that do consider U-turn maneuvers explicitly in their criteria. The responses indicate that only 16 percent of highway agencies have a formal policy on median opening design and location that considers U-turn maneuvers, while 84 percent of highway agencies do not have such a policy.
|
From page 98... ...
generally prohibit U-turn maneuvers at unsignalized median openings. Question 11 -- Criteria for U-Turn Prohibitions at Median Openings Question 11 asked highway agencies whether they have formal policies on when to prohibit U-turn maneuvers at specific median openings.
|
From page 99... ...
Question 12 -- Median and Roadway Widths Required to Provide for U-turns at Unsignalized Median Openings Question 12 asked highway agencies about the median width required by their agencies to provide for U-turns at unsignalized median openings. Fifteen state and five local agencies (or 53 percent of the agencies responding)
|
From page 100... ...
Question 16 -- Safety or Operational Problems at Unsignalized Median Openings Question 16 asked highway agencies whether they had experienced safety or traffic operational problems at unsignalized median openings. Table B-22 shows the number and percentage of highway agencies that indicated that they had experienced such problems at unsignalized median openings.
|
From page 101... ...
Number of agencies State agencies Local agencies Total Factors related to safety or operational problems Yes No Yes No Yes No Operational considerations (congestion, trucks) 10 0 10 7 20 7 Median too narrow 10 1 6 10 16 11 Driveway nearby 6 3 10 8 16 11 Poor roadway geometry 8 1 7 9 15 10 Roadway too narrow 8 3 6 11 14 14 Median opening within the functional area of an intersection 5 4 7 8 12 12 Insufficient sight distance 6 3 5 10 11 13 Frequency/density of median openings 4 6 6 9 10 15 Median opening across from right-turn lane 3 7 1 14 4 21 Median opening too long 5 5 4 11 9 16 Median opening within left-turn lane 4 5 4 12 8 17 Inconsistent application 4 5 5 9 9 14 Median too wide 4 6 4 11 8 17 TABLE B-23 Factors identified by highway agencies as related to the safety or operational problems they encountered at unsignalized median openings Number (percentage)
|
From page 102... ...
Question 19 -- Increase in U-Turn Volumes at Adjacent Median Openings Caused by the Installation of Raised Medians to Eliminate Direct Left-Turn Access to Intersections or Driveways In Question 19, highway agencies were asked whether they had experienced increases in U-turn volumes at median openings, as a result of projects in which a raised median that eliminated direct left-turn access to one or more intersections or driveways was installed. Table B-27 shows that more than half of the responding agencies indicated that they had implemented such projects recently (during the last 5 to 7 years)
|
From page 103... ...
Question 20 -- Closing of Existing Unsignalized Median Opening Resulting in Increased U-Turn Volumes at Median Openings Elsewhere on the Same Roadway Question 20 asked highway agencies whether they had implemented projects in which existing unsignalized median B-14 openings were closed eliminating direct left-turn access to one or more intersections or driveways, and resulting in increased U-turn volumes at median openings elsewhere on the same roadway. The responses to this question are summarized in Table B-32.
|
From page 104... ...
Table B-36 summarizes the number of state and local agencies that have projects involving closure of unsignalized median openings that may be suitable for evaluation as part of this research. Nine agencies (five state and four local agencies)
|
From page 105... ...
23 (71.9) 32 TABLE B-36 Number of agencies that may have projects involving closure of existing unsignalized median openings that may be suitable for evaluation as part of this research
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.