Browsing by Subject "Warning signs"

Now showing 1 - 10 of 10
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    Advanced LED Warning Signs for Rural Intersections Powered by Renewable Energy
    (Minnesota Department of Transportation Research Services Section, 2010-12) Kwon, Taek Mu; Weidemann, Ryan
    A majority of intersection-related fatal crashes occur at rural, through/stop intersections. At these intersections, sight restrictions caused by vertical and horizontal curves negatively affect a driver’s ability to safely accept a gap in the traffic stream. Static advanced warning signs are sometimes installed at these intersections to warn drivers on the main, through approaches that an intersection is ahead. These warning signs appear to be ineffective. A new Advanced Light-Emitting Diode (LED) Warning System was developed and deployed at a rural, through/stop intersection with limited intersection sight distance due to a severe vertical curve. This warning system actively detects vehicles on all approaches and activates LED blinker warning signs for the conflicting movements. The research project included analysis of driver behavior obtained through video data and a survey of local residents and frequent users of the intersection. This report describes the development, implementation, and evaluation results of this new warning system.
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    Advanced LED Warning System for Rural Intersections: Phase 2 (ALERT-2)
    (Minnesota Department of Transportation, 2014-02) Kwon, Taek M.; Ismail, Husam
    This report presents findings of the second phase of the Advanced LED Warning System for Rural Intersections (ALERT) project. Since it is the next generation of the same system, the second phase system is referred to as the ALERT-2 system while the first system is referred to as the ALERT-1 system. The ALERT systems demand use of four basic Intelligent Transportation Systems (ITS) technologies: LED-based signs, renewable energy, non-intrusive sensors, and wireless communication. Use of these four basic technologies remained the same for both phases of the system. In the first phase, the data showed that the ALERT-1 system reduced vehicle speeds on the main approach, increased STOP wait time on minor approaches, and eliminated roll-throughs for vehicles on minor approaches when a conflict existed in the intersection. However, when no conflict exists in the intersection, an increase in roll-throughs for vehicles on the minor approaches was observed. The ALERT-2 system was redesigned to mitigate this increased roll-throughs. With respect to technological advances, the ALERT-2 system improves many aspects of the basic technologies, providing higher system reliability, easier installation and maintainability, and better self-sustainability through redesign of the renewable energy application. To assess the driver behaviors at the test site, 13 moths worth of video data and a survey of local residents were collected. This report describes the system development, implementation, and analysis of the video and survey data.
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    The Design of a Minimal Sensor Configuration for a Cooperative Intersection Collision Avoidance System - Stop Sign Assist: CICAS-SSA Report #2
    (2010-08) Gorjestani, Alec; Menon, Arvind; Cheng, Pi-Ming; Shankwitz, Craig; Donath, Max
    The deployment of a Cooperative Intersection Collision Avoidance System – Stop Sign Assist (CICAS-SSA) can save lives by addressing the causal factor of crashes at rural thru-Stop intersection: drivers who stop on the minor leg of the intersection, improperly assess the gaps in the traffic on the major leg, proceed, and are then hit. The prototype CICAS-SSA system consisted of a network of sensors covering both the minor and the major legs of the intersection. Sensors on the minor road monitored the approach of vehicles and classified them based on their length and height. Sensors along the major road were arrayed to track vehicles (and the gaps between them) approaching the crossroads from 2000 feet away as a means to ensure that the tracking algorithm had sufficient time to “lock on” and track all approaching vehicles. Because cost is a primary concern for any highway safety application, the development of a “minimal sensor set” which would provide adequate safety performance for minimum cost was paramount to the success of the CICAS-SSA program. This report documents the development of this minimal sensor configuration.
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    Determination of the Alert and Warning Timing for the Cooperative Intersection Collision Avoidance System-Stop Sign Assist Using Macroscopic and Microscopic Data: CICAS-SSA Report #1
    (2010-08) Gorjestani, Alec; Menon, Arvind; Cheng, Pi-Ming; Shankwitz, Craig; Donath, Max
    Crashes at rural thru-stop intersections arise primarily from a driver attempting to cross or enter the mainline traffic stream after failing to recognize an unsafe gap condition. Because the primary cause of these crashes is not failure to stop, but failure to recognize an unsafe condition, the US DOT FHWA, MnDOT, and the University of Minnesota ITS Institute undertook the Cooperative Intersection Collision Avoidance System – Stop Sign Assist (CICAS-SSA) program. CICAS-SSA uses roadside radar sensors, a computer processor and algorithms to determine unsafe conditions, and an active LED icon based sign to provide timely alerts and warnings which are designed to reduce the frequency of crashes at rural expressway intersections. The focus of this report is the alert and warning timing used to provide a driver with assistance in recognizing and taking appropriate action when presented a gap which could be considered unsafe. The work presented herein uses both macroscopic data collected by roadside sensors and data acquisition equipment in Minnesota, Wisconsin, and North Carolina, and microscopic data collected using an instrumented vehicle and test subjects at the Minnesota Research Intersection, located at the intersection of US Hwy 52 and Goodhue County Road 9. Three tenets that are particularly germane to the determination of alert and warning timing for the CICAS-SSA system are: (1) the system does not help a driver choose a safe gap; it is designed to assist a driver with unsafe gap rejection, (2) it indicates when it is unsafe to proceed, not when it is safe to proceed, and (3) it must complement good decision making, and address those instances where poor decision making could lead to a crash.
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    Macroscopic Review of Driver Gap Acceptance and Rejection Behavior at Rural Thru-Stop Intersections in the US - Data Collection Results in Eight States: CICAS-SSA Report #3
    (2010-08) Gorjestani, Alec; Menon, Arvind; Cheng, Pi-Ming; Newstrom, Bryan; Shankwitz, Craig; Donath, Max
    Crashes at rural thru-stop intersections arise primarily from a driver attempting to cross or enter the mainline traffic stream after failing to recognize an unsafe gap condition. Because the primary cause of these crashes is not failure to stop, but failure to recognize an unsafe condition, the US DOT FHWA, MnDOT, and the University of Minnesota ITS Institute undertook the CICAS-SSA program. CICAS-SSA uses roadside radar sensors, a computer processor and algorithms to determine unsafe conditions, and an active LED icon based sign to provide timely alerts and warnings which are designed to reduce the frequency of crashes at rural expressway intersections. These rural, thru-stop crashes are problems in many states. In conjunction with the CICAS-SSA program, MnDOT and the University of Minnesota led a nine-state (CA, GA, IA, MI, MN, NC, NH, NV, and WI) pooledfund study whereby driver behavior data at rural thru-stop intersections was collected by the Minnesota Mobile Intersection Surveillance System (MMISS). The ultimate goal of the pooled fund study and the analysis of that data described here, was to identify whether drivers in different regions of the county exhibit different gap acceptance/rejection behavior, and if different driver behaviors are identified, determine whether they are different enough to inhibit the deployment of a common CICAS-SSA design throughout the US. The analysis of the data indicated that the system can indeed be deployed nationally.
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    Portable, Non-Intrusive Advance Warning Devices for Work Zones with or without Flag Operators
    (Minnesota Department of Transportation Research Services, 2012-10) Hourdos, John
    The main objective of this study was to develop a work zone alert system informing speeding drivers of the upcoming work zone and raising their attention level before they reach the taper line and/or the work zone flag operator. The resulting system, termed Intelligent Drum Line (IDL), is capable of delivering visual and auditory warnings, targeting vehicles that are exceeding the posted or temporary speed limit upstream of the work zone. The IDL system, in its final incarnation, is the best compromise that can be reached between developing a low-cost system that is rugged enough to be deployed on the shoulder of high-speed roadways and comprised of as few individual parts as possible so a single work zone worker can deploy and move the system as the work zone operations are progressing and delivery of a warning targeted only at vehicles that are going faster than the desired speed set by the work zone crew. The IDL system has been tested in the MnROAD facility, targeting vehicles ranging from regular passenger vehicles to a 3-ton snowplow truck. The auditory warning has been successful in penetrating the vehicle cab and loud enough to attract the attention of the driver. Although, still in a prototype stage, the IDL system has received high marks from MnDOT engineers and work zone workers. Further development is needed to ensure that the final product is crash proof and that it can be produced efficiently.
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    Sign Comprehension, Considering Rotation and Location, Using Random Gap Simulation for a Cooperative Intersection Collision Avoidance System – Stop Sign Assist: CICAS-SSA Report #4
    (2010-08) Creaser, Janet; Manser, Michael; Rakauskas, Michael; Donath, Max
    Crashes at rural thru-stop intersections arise primarily from a driver attempting to cross or enter the mainline traffic stream after failing to recognize an unsafe gap condition. Because the primary cause of these crashes is not failure to stop, but failure to recognize an unsafe condition, the US DOT FHWA, MnDOT, and the University of Minnesota ITS Institute undertook the CICAS-SSA program. CICAS-SSA uses roadside radar sensors, a computer processor and algorithms to determine unsafe conditions, and an active LED icon based sign to provide timely alerts and warnings which are designed to reduce the frequency of crashes at rural expressway intersections. The primary goal of this portion of the overall effort was to evaluate several candidate CICAS-SSA concepts in order to identify a single sign that may provide the greatest utility in terms of driver performance and usability at a real-world rural intersection. A secondary goal of the work was to determine the ideal physical characteristics (i.e., location and rotation of a sign relative to drivers) of the candidate CICAS-SSA at a test intersection to maximize comprehension (and subsequent use) of the sign. This report summarizes the results of the work.
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    User-centered Smart Traffic Sign Development Study
    (Minnesota Department of Transportation, 2023-06) Morris, Nichole L.; Rajamani, Rajesh; Drahos, Bradley A.; Xie, Zhenming; Alexander, Lee; Kessler, William
    Flaggers protect workers by providing temporary traffic control and maintaining traffic flow through a work zone. They are often the first line of defense to stop distracted, inattentive, or aggressive motorists from intruding into the work area. This project aims to develop an automated intrusion detection system to alert drivers who are unsafely approaching or entering a flagger-controlled work zone. A human factors user needs assessment found maintenance workers preferred a modified traffic signal to feature the alert system due to flagger risks of being in the roadway and drivers failing to stop and remain stopped when presented with the STOP side of the flagger sign. A modified traffic signal that could be operated using a handheld remote was developed. The low-cost embedded electronics on the traffic signal enabled it to track trajectories of nearby vehicles, detect potential intrusions, and trigger audio-visual warnings to alert the intruding driver. Usability testing in a simulated driving test found poor expectancies and stopping rates of the traffic signal-based alarm system compared to a traditional flagger but did demonstrate evidence that drivers may be less likely to stop and remain stopped with the flagger STOP sign than the red ball indicator of the traffic signal. Furthermore, some drivers corrected their initial stopping error after triggering the auditory alarm of the traffic signal. A follow up test found improved performance with the alert system incorporated into an audiovisual enhanced STOP/SLOW flagger paddle. Testing of the developed sensor system found the system capable of simultaneous multivehicle tracking (including estimation of vehicle position, velocity, and heading) with a range of up to 60 meters and angular azimuth range of 120 degrees and correctly detecting all test intruding vehicles.
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    Validation Study – On-Road Evaluation of the Cooperative Intersection Collision Avoidance System – Stop Sign Assist Sign: CICAS-SSA Report #5
    (2010-08) Rakauskas, Michael; Creaser, Janet; Manser, Michael; Graving, Justin; Donath, Max
    The CICAS-SSA sign is a roadside driver support system that is intended to improve gap rejection at rural stopcontrolled intersections. The CICAS-SSA system tracks vehicle locations on a major roadway and then displays a message to a driver on the minor road via an active LED icon-based sign. The basis of this sign is a “Divided Highway” sign that is commonly presented in traffic environments. Overlaid on the roadways of the sign are yellow or red icons that represent approaching vehicles that are at a distance at which the driver on the minor road should proceed with caution or at a distance that is considered unsafe to enter the intersection. Previous research conducted in a driving simulation environment indicated potentially beneficial changes in driver decision-making relative to approaching vehicle gap sizes and indicated that drivers perceive the system as being both useful and satisfying. While simulation-based evaluations provide a wealth of useful information, their ability to replicate the full array of behavioral, cognitive, and perceptual elements of a driving environment do have some limitations. It is because of these limitations that it is useful to confirm simulation-based findings in a real-world environment. The primary goal of the current work was to evaluate the candidate CICAS-SSA sign in a real-world setting to confirm previously identified benefits and identify any unintended consequences of sign usage. This goal was accomplished through a validation field test performed at the intersection of US Highway 52 and County Road 9 in Southern Minnesota. The findings of the work are summarized in this report.
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    Vehicle Speed Impacts of Occasional Hazard (Playground) Warning Signs
    (Minnesota Department of Transportation, 2012-02) Davis, Gary; Knapp, Keith K.; Hourdos, John
    The main objective of this study was to estimate the speed impact of occasional hazard (playground) warning (OHPW) signs along residential streets. Three types of data were collected at each of three study sites approximately one month before and one week to one month after the installation of a pair of OHPW signs. Vehicle speed data were collected with a pneumatic tube device. Manual observations were recorded, and focused on the magnitude and location of the on-street parking and park and/or playground activities occurring at the study sites. Linear regression analysis was used to estimate the change in mean vehicle speed associated with the presence of the OHPW signs, while controlling for the effects due to activity levels on the streets and the playgrounds. At one site the OHPW sign had no discernible effect on mean vehicle speeds, while at the other two sites mean vehicle speeds decreased by 1.5 mph and 0.9 mph following installation of the OHPW signs.