Frequently Asked Questions
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What is remote sensing?
What are the benefits of using remote sensing?
How long does it take to test a vehicle's emissions?
Where can the equipment be used?
What gases can the AccuScan equipment test?
How long does it take to implement a Remote Sensing Program?
How many vehicles annually can be tested with the AccuScan equipment?
How many people are needed to operate the AccuScan equipment?
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Q. What is remote sensing?
A. Remote Sensing, when applied to vehicle emissions testing, refers to the measurement of vehicle exhaust emissions with roadside monitoring systems (known as remote sensing devices or RSD’s), as the vehicle passes by without interfering with or altering the vehicle progress.
Infrared (IR) and Ultraviolet (UV) light is directed across the road and passively reflected back to detectors that monitor light intensity at characteristic wavelengths. The amount of characteristic infrared or ultraviolet light absorbed is translated into the exhaust concentration of the three regulated pollutants of interest, carbon monoxide, hydrocarbons and nitrogen oxides.
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Q. What are the
benefits of using Remote Sensing equipment?
A. -Speed: Individual vehicle emissions are measured in less than a second.
-Convenience: Emissions are measured unobtrusively as the vehicle passes by.
-Efficiency: Remote sensing can be used to screen vehicles on the road and thereby supplement traditional vehicle inspection programs.
-Cost: Supplementing traditional emissions testing at fixed facilities with on-road remote sensing can reduce the overall cost of the program.
-Effective: Remote sensing is considered one of the most effective ways of evaluating I/M program performance.
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Q. How
long does it take to test a vehicle’s emissions?
A. Background levels before the car are subtracted for exhaust levels to compute the vehicle pollutants emissions. A digital image of the license plate is captured. The speed and acceleration of the vehicle is measured. All these data along with other relevant information are recorded to complete the remote sensing test in less than one second.
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Q.
Where can the equipment be used?
A. The AccuScan RSD (Remote Sensing Device) can be placed on a roadway that allows for a distance of 17 to 23 feet, or 5 to 7 meters, between the SDM (Source Detector Module) and VTM (Vertical Transfer Mirror) in order to monitor a single lane of traffic flowing in one direction. The ideal mode of operation for measurement is slight acceleration. We often find this mode at on-ramps to highways with uphill grades and vehicle speeds between 35 & 45 MPH.
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Q.
What gases can the AccuScan equipment test?
A. The AccuScan RSD3000 measures all regulated criteria pollutants: HCs CO, CO2, and NOx. The AccuScan RSD4000 measures those four and smoke. We are looking into including NO2 and SO2 channels in the future.
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Q.
How long does it take to implement a Remote Sensing program?
A. This depends on the size, scope, and type of the Remote Sensing program. If the goal is a general motor vehicle fleet survey, for example, with one or two AccuScanTM devices, the time from concept to launch can be very quick (e.g. 2 months). If it is a long term screening program, covering a large fleet of vehicles with multiple AccuScanTM devices, the time from concept to launch will be longer (6 – 9 months), but it is still faster than other vehicle emissions testing methods.
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Q.How many vehicles annually
can be tested with the AccuScan?
A. Remote sensing measurements are weighted by vehicle miles traveled. The more often the vehicle is on the road the more likely it will be tested by a remote sensing device. In contrast, inspection programs measurements are driven by registration renewals. Our experience in long-term continuous programs has been measurement of approximately 80% of the registered population when remote sensors are deployed for passive on-road measurement. Programs that include some active recruitment such as advertised car-care clinics can increase the coverage. Some registered vehicles travel too infrequently to be captured by a remote sensor.
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Q.
How many people are needed to operate the AccuScan?
A. A single trained operator is all that is needed to operate the AccuScanTM equipment.
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