Author: U.s. Department of Transportation
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723432101
Category :
Languages : en
Pages : 100

Get Book Here

Book Description
Synthesis of variable speed limit signs /

Author: Bryan Katz
Publisher:
ISBN:
Category : Speed zoning (Traffic engineering)
Languages : en
Pages : 85

Get Book Here

Book Description
Variable speed limit (VSL) systems utilize information on traffic speed, occupancy, and volume detection, weather, and road surface conditions to determine the appropriate speeds at which drivers should be traveling, given current roadway and traffic conditions. The use of VSL during less than ideal conditions, such as heavy traffic and adverse weather, can improve safety by decreasing the risks associated with traveling at speeds that are higher than appropriate for the conditions and by reducing speed variance in traffic. In addition, VSL can be used to dynamically manage speeds during planned (rush hour congestion) and unplanned (incidents) events. Used in conjunction with managed lanes and other active traffic management strategies, VSL can respond to downstream congestion to eliminate or delay bottlenecks and mitigate the possibility of crashes. Based on a comprehensive literature review along with agency interviews to gather information on existing, deactivated and planned VSL systems, this synthesis provides a comprehensive review of current practices on VSL operations, particularly experiences from deployments in the United States, and to identify successful and best practices from the following perspectives: planning and policy, design, deployment, and standards, operations and maintenance, and outcomes.

Author: Matt Riffkin
Publisher:
ISBN:
Category : Highway communications
Languages : en
Pages : 37

Get Book Here

Book Description
Technological advances allow speed limits to be changed in real time based on actual roadway conditions. There may be potential advantages to using variable speed limits in Utah, such as for traffic control during construction where the speed limit may be lowered adjacent to actual construction activities versus at other times or locations within an established work zone. This research will test the compliance and derive potential advantages from the use of variable speed limit equipment.

Author: Disapat Lavansiri
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 312

Get Book Here

Book Description

Author: Gerry John Forbes
Publisher: Transportation Research Board
ISBN: 0309143217
Category : Rural roads
Languages : en
Pages : 114

Get Book Here

Book Description
TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 412: Speed Reduction Techniques for Rural High-to-Low Speed Transitions explores techniques for lowering traffic speeds in rural transition zones. Transition zones are those portions of high-speed roads that have lower posted speed limits as the roadway approaches a settlement.

Author:
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 4

Get Book Here

Book Description
This guideline provides guidance when collocating static and dynamic signs on the same supporting gantry as variable speed limit (VSL) signs.

Author: Nicholas J. Fudala
Publisher:
ISBN:
Category : Road work zones
Languages : en
Pages : 42

Get Book Here

Book Description
Variable speed limit (VSL) systems have been used in a number of countries, particularly in Europe, as a method to improve flow and increase safety. VSLs use detectors to collect data on current traffic and/or weather conditions. Posted speed limits are then dynamically updated to reflect the conditions that motorists are actually experiencing. Presenting drivers with speed limits that are appropriate for current conditions may reduce speed variance, a concept sometimes called speed harmonization. If properly designed, VSL systems have been shown to reduce crash occurrence and can also reduce system travel time through increased uniformity in traffic speeds. High-volume urban work zones tend to be prone to congestion and safety problems, and VSLs may be one way to ameliorate these issues. VSLs were recently installed at a high-volume, congested urban work zone located on I-495 (the Capital Beltway, hereinafter the Beltway) between the Springfield Interchange in Springfield, Virginia, and the Virginia-Maryland state line on the Woodrow Wilson Memorial Bridge. VSL signs were activated in late July 2008, but initial evaluations of the system showed inconclusive effects. Changing site conditions made a direct before-and-after evaluation of the system deployed in the field problematic, and some problems with the control algorithm were also noted. Given the difficulties in evaluating the system deployed in the field, a calibrated simulation of the site was constructed to assess the effects of the VSL system on traffic operations and safety surrogate measures. The simulation platform also provided an opportunity to examine a number of system configurations to assess how changes in system design and driver behavior might affect a variety of measures. The results indicated that the VSL could create substantial improvements in traffic operations provided the demand did not exceed capacity by too large a margin. The location of the VSL signs played an important role in operational performance. The study recommends that the Virginia Department of Transportation continue to pursue this technology but carefully scrutinize algorithm design and VSL sign placement. Further, a cost/benefit analysis indicated that VSLs may be most appropriate for long-term applications.

Author: Byungkyu Park
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 188

Get Book Here

Book Description
There has been a considerable increase in the amount of construction work on the U.S. national highways in recent years. This is a direct result of the current transportation policies emphasis on the maintenance of existing facilities rather than on building new ones. But with the increase in the amount of traffic on the interstates, the safety at the construction sites is getting worsened. Variable speed limit (VSL) systems are a kind of intelligent transportation systems (ITS) technology and they try to increase safety by posting the maximum or minimum speed limits. The speeds to be posted on the VSL signs are calculated manually or with the help of algorithms. This study is an attempt to evaluate the performance of various speeds at work zones and to develop VSL control logics that would calculate suitable speeds for different traffic conditions. The research is conducted by simulating a postulated test-bed network and then validating the results by simulating a real world work zone site. The study uses a microscopic simulation model - VISSIM. The study developed a safety surrogate measure, minimum safety distance equation (MSDE), to quantify safety. Travel times have primarily been used to quantify mobility. Since most of the existing VSL control logics consider only the traffic advisory speed or average traffic speed, an attempt was made to develop a logic that would consider both safety and mobility in calculating speeds. The results of simulating the postulated network indicated that the performance of speeds varied with traffic demand volumes and compliance rate conditions. In general an increase in speed decreased safety, but improved travel time. Surprisingly at low volume and low compliance conditions an increase in speed also improved safety. In order to find the speeds that provide optimal measures of safety and mobility a normalization procedure that combines travel time and safety measures is used. The performance of the logics is mixed. In general logic 3 (that considers both safety and mobility measures to calculate VSL speed) performed better than logics 1 and 2 (that use average traffic speed). However logics 1 and 2 performed better than Logic 3 for oversaturated conditions and for low volume and low compliance conditions. Statistical analysis was performed to substantiate the results of the base cases and the logics. The performance of the VSL system was also evaluated by simulating a real world work zone site at Covington, Virginia. The results were found to be consistent with those of the postulated network.

Author:
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 19

Get Book Here

Book Description
This guideline defines the placement and mounting requirements for variable speed limit signs (VSLS) and variable speed limit and lane control signs (VSL / LCS) on motorways, long bridges and in tunnels. Please check provided website / URL for currency.

Author: M. D. Harmelink
Publisher: TAC = ATC
ISBN: 9781551872148
Category : Speed limit
Languages : en
Pages : 124

Get Book Here

Book Description
Speeding in work zones is one of the most common traffic violations observed by road builders and road maintenance crews. It creates an unsafe environment for road workers and all types of road users. This synthesis is intended to help address this situation by reviewing work zone speed management efforts in Canada and the United States. The report provides an overview of technologies and methods for managing speed in work zones, with topics ranging from posted speed limit reductions and narrowing lanes to portable variable message signs and enforcement. In addition, the report discusses other methods for speed management, including merge control, driver and worker education, and real-time traffic information systems. The report also provides a number of conclusions and recommendations based on the synthesis, which identify some of the key problems and solutions.