REVERSIBLE ROADWAY CONTROLS
CAPACITY IS GENERALLY THOUGHT OF AS A FUNCTION OF THE NUMBER OF LANES, BUT WITH COMPLETION OF THE INTERSTATE DRAWING NEAR AND THE ABILITY OF EXISTING CITIES TO PROVIDE MORE CORRIDORS REACHING ITS MAXIMUM, ATTENTION NEEDS TO BE GIVEN TO MEANS OF OPTIMIZING THE USE OF EXISTING SPACE. ONE MEANS IS REVERSIBLE ROADWAYS, THE CHARACTERISTICS, WARRANTS, AND APPLICATIONS OF WHICH ARE DESCRIBED IN THE PRESENT ARTICLE. PARTICULAR ATTENTION IS GIVEN TO CONTROL SYSTEMS, I.E., THE SIGNALS, SIGNS, AND BARRIERS THAT GUIDE THE TRAFFIC STREAM INTO, THROUGH, AND OUT OF THE REVERSIBLE LANES AT PROPER TIMES AND IN PROPER DIRECTIONS. BECAUSE OF THEIR EASE OF CORRELATION WITH THE LANE, OVERHEAD SIGNALS ARE THE PREFERRED CONTROL DEVICE, BUT SOME CITIES---NOTABLY THE DISTRICT OF COLUMBIA---HAVE OPPOSED THEIR USE. A VARIETY OF ROADWAY SIGNALS HAS BEEN TRIED, BUT EXPERIENCE IS MUCH LESS ADVANCED THAN WITH OVERHEAD SIGNALS. IN SAN DIEGO A BRIDGE WITH A REVERSIBLE CENTER LANE WAS EQUIPPED WITH AN ARRAY OF CENTER-LANE LIGHTS THAT APPEAR AS A GREEN ARROW TO MOTORISTS IN THE DIRECTION OF TRAFFIC FLOW AND AS A DIAGONAL RED LINE TO OPPOSING TRAFFIC. SEVERAL CHANGEABLE MESSAGE SIGNS HAVE BEEN DEVELOPED FOR THE SAME PURPOSE; AS AN ANSWER TO OBJECTIONS TO THE HAZARDS AND APPEARANCE OF SIGN SUPPORTS, HOLOGRAPHIC DISPLAYS HAVE BEEN DEVELOPED, AS HAVE PAVEMENT MARKINGS FLIPPED FROM ONE SIDE TO THE OTHER BY A JET STREAM IN THE PAVEMENT. BARRIERS IN THE FORM OF CONES, STANCHIONS, ETC. SUFFER THE SAME DRAWBACK AS MANUALLY TENDED SIGNS: MAINTENANCE AND LABOR. PNEUMATICALLY CONTROLLED POP-OUT STANCHIONS, TRIED AT SEVERAL LOCATIONS IN CALIFORNIA, HAVE NOT YET PROVED EFFECTIVE. NO AUTOMATIC SYSTEM OF SIGNALS, SIGNS, OR BARRIERS IS SUFFICIENTLY RELIABLE THAT IT CAN DO WITHOUT SURVEILLANCE. IT IS SUGGESTED THAT TWO SYSTEMS BE GIVEN EXTENSIVE FURTHER TRIAL: (1) LIGHTS MOUNTED AT ROADWAY LEVEL LEND THEMSELVES TO AUTOMATIC REMOTE CONTROL AND TO EASY MAINTENANCE; (2) COMMERCIALLY AVAILABLE PNEUMATIC POSTS NEED ATTENTION TO AIR-SUPPLY DESIGN AND TO THE REFLECTIVITY AND VISIBILITY OF THE POSTS. AN APPENDIX LISTS THE CHARACTERISTICS OF BRIDGE, TUNNEL, AND FREEWAY REVERSIBLE-LANE CONTROL SYSTEMS IN USE TODAY.
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Availability:
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Corporate Authors:
Eno Transportation Foundation
1250 I Street, NW, Suite 750
Washington, DC United States 20005 -
Authors:
- Lathrop, W H
- Publication Date: 1972-1
Media Info
- Pagination: p. 133-147
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Serial:
- Traffic Quarterly
- Volume: 26
- Issue Number: 1
- Publisher: Eno Transportation Foundation
- ISSN: 0041-0713
Subject/Index Terms
- TRT Terms: Barriers (Roads); Reversible traffic lanes; Road markings; Traffic control devices; Traffic signals; Traffic signs
- Uncontrolled Terms: Barriers
- Old TRIS Terms: Traffic marking
- Subject Areas: Highways; Operations and Traffic Management;
Filing Info
- Accession Number: 00226266
- Record Type: Publication
- Files: TRIS
- Created Date: May 16 2001 12:00AM