Utilization of Current Technologies to Capture Sign and Pavement Marking Retroreflectivity
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Transcript of Utilization of Current Technologies to Capture Sign and Pavement Marking Retroreflectivity
Utilization of Current Technologiesto Capture Sign and Pavement Marking Retroreflectivity
Sign MUTCD Retroreflectivity Compliance Dates
January 2012 June 2014 – Implementation and continued use of an assessment or management method that is designed to maintain traffic regulatory and warning sign retroreflectivity at or above the established minimum levels
• January 2015 - Replace identified regulatory, warning, ground-mounted guide signs (except street-name)
January 2018 - Replace identified street name & overhead guide signs
May 14, 2012 Eliminated 46 items
Revised 4 others items Safety related compliance dates maintained (8)
Revision #2 of the 2009 MUTCD
Requirements of a Traffic Sign Visible to the driver
adequate levels of retroreflectivity and luminance (amount of light received by driver)
Nighttime more critical than daytime
fatalities
The use of the state of the art in cameras, illumination and computer vision allow a new assessment method
based into an objective and repetitive measure,
carried on in an automatic way, of the traffic signs in their actual context.
1. Visual nighttime inspection
2. Measured sign retroreflectivity
3. Expected sign life
4. Blanket replacement
5. Control signs
6. Others
MUTCDMaintenance and Inspection Methods
Technology
luminance cd/m2 (candela/m2) Illuminance = lx (lux)
INCIDENT LIGHT
(ILLUMINANCE)
REFLECTED LIGHT
(LUMINANCE)
Retroreflectivity (RA = = cd/lx/m2 ) @20 α (observation angle) luminanceilluminance
Components of Retroreflectivity
α
Luminance MeasurementHigh sensitivity cameras installed on board measures the luminance, even under low light conditions
The response curve of the cameras is equivalent to the human eye, and allows
to measure luminance consistently
Illuminance Control
A specific lighting system, computer regulated and calibrated
Provides a highly repetitive measurement. Non-glaring for road users
Calculated Illumination
LEDs + van headlights Van headlights
Luminance reflected from only the LED headlight (illuminance known)
Dual cameras and computer algorithms eliminate ambient light sources
leaving a controlled and known illuminance value
=-minus
GeometryCameras sensors are
geometrically calibrated to measure distances and
dimensions in the scene
Together with the multiple sensors on board measure the geometry context of the retroreflectivity measurement
AMAC data is based on the actual performance of the traffic sign Sign Quality as Perceived by Operator
as seen by the driver at night
Data Characteristics Retroreflectivity (background and legend) for all colors of
post-mounted-signs and overhead structures Sign luminance Contrast Ratio for warning signs (legend / background) Sign size, height above the roadway MUTCD code Evaluation from the driver eye perspective Traffic sign inventory with GPS positional data Optimizes traffic signs maintenance by providing
quantitative retro values
Accuracy Testing All tests preformed at TTI
(Texas Transportation Institute -Texas A&M University)
Performance Criteria Static Closed-Course Dynamic Closed-Course Dynamic Open-Road
Evaluation of background and legend retroreflectivity measurements
Dynamic Open-Road Testing
12-mile route Rural divided high speed highway Undivided highway Low speed urban roadways With and without roadway lighting
Dynamic Open-Road Results: Background
Repeatability
Advantages of Mobile Platform
Cost effective Measures sign from drivers perspective No traffic control necessary Safety – no workers in active traffic Actual sign retro measurements to be used
in degradation analysis Complete data capture for engineering
analysis
Mobile Pavement Marking Retroreflectivity
Multiple Line Data Capture
utilizes digital image processing
Pavement Markings Retroreflectivity Data Capture
The AMAC system utilizes the onboard image processing system to capture pavement marking retroreflectivity.
This includes striping, and pavement graphics. The system measures retroreflectivity values
as well as dimensions for all markings within and adjacent to the lane of travel.
AMAC
For further information on AMACvisit our website at www.amacglobal.comToll Free: 855.DBi.AMAC (855.324.2622)
Email: [email protected]