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: info@amacglobal.com