Patent Publication Number: US-6671630-B2

Title: System and method for remote analysis of small engine vehicle emissions

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 09/740,853, filed Dec. 21, 2001 now U.S. Pat. 6,560,545 which claims priority to U.S. provisional application serial No. 60/173,514, entitled “SYSTEM AND METHOD FOR REMOTE ANALYSIS OF SMALL ENGINE VEHICLE EMISSIONS,” filed on Dec. 29, 1999. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a system and method for remote analysis of emissions from vehicles with small engines, such as motorcycles. 
     BACKGROUND OF THE INVENTION 
     Internal combustion engines produce gaseous by-products during operation. Many of these gaseous by-products pollute the environment and, in high concentrations, can be extremely harmful. The cumulative effect of these pollutants, especially from automobiles and other vehicles, has had a significant impact on air quality and ozone depletion throughout the world. 
     In order to curb vehicle emissions, many states have instituted Inspection and Maintenance (IM) programs. Some IM programs include periodic inspections conducted at state run facilities. These inspections involve operating the vehicle through a series of accelerations, decelerations, stops, and starts on a chassis dynamometer and collecting the vehicle&#39;s emissions in an analyzer. These inspections take time and are inconvenient for vehicle owners. 
     To this end, remote sensing systems have been under development for many years. For example, U.S. Pat. No. 5,210,702 discloses a system for remotely detecting carbon monoxide and carbon dioxide levels in vehicle emissions. The system used an infrared (IR) source to project a collimated beam of IR radiation through the exhaust plume of a passing vehicle. Optical apparatus was used to separate various wavelengths of the beam and direct them to particular photodetectors. Each photodetector generated an electrical signal based on the presence or absence of light of a specified wavelength. The electrical data was fed into a computer which is used to calculate and compare the ratios of carbon monoxide and carbon dioxide exhaust components. From those ratios, high emitting vehicles were identified. These ratios could also be put into a series of equations based on the stoichiometric relationships between the exhaust components which are used to compute the concentrations which would be observed by a tailpipe probe (corrected for water and any excess air). 
     Other methods of determining emission concentrations using remote optical gas analyzers were also attempted. One method, disclosed in U.S. Pat. No. 4,924,095, used multiple beam paths to sample a cross-sectional “slice” of the exhaust plume. The volume of the slice was determined and used to calculate an absolute concentration of one or more exhaust components. Such a system proved inaccurate and unworkable in practice due to irregular dispersion of the exhaust plume and significant difficulties in calculating the volume of the exhaust plume. 
     Remote vehicle emission testing systems have undergone many improvements since originally disclosed. Some examples include: linked video surveillance of the vehicle whose emissions were to be analyzed and license plate readers to actually “read” the license plate; the combination of UV and IR radiation sources for detectors with CO, CO 2 , NO x , water, and hydrocarbon (HC) detector channels; and various optical arrangements effecting beam splitting, beam paths, filtering, and time multiplexing. 
     While cars and trucks are the largest source of polluting vehicle emissions, vehicles with smaller engines, such as motorcycles, mopeds, and other small motorized vehicles may also contribute to the accumulation of pollutants in urban areas. Because the engines of small motorized vehicles typically generate considerably smaller and less dense exhaust plumes, present remote sensing systems for cars and trucks may have difficulty distinguishing exhaust readings for small motorized vehicles from background noise. For example, a 50 cc moped produces an exhaust plume ten to twenty times less than that of a small car. 
     Further, the spatial location of small engine exhaust plumes can be critical to successful remote sensing due to their small size and rapid dispersion. Due to the variability in the height of motorcycle exhaust outlets, a motorcycle exhaust plume may occur anywhere between 6 in. and 3 ft. above the ground. Present remote sensing systems may have difficulty targeting the exhaust plume of vehicles with small engines and variable height exhaust outlets. 
     These and other drawbacks of present remote emission sensing systems are overcome by one or more of the various preferred embodiments of the invention. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a system and method for detecting and measuring the relative concentrations of gases in the exhaust of moving vehicles with small engines. 
     This and other objects of the present invention may be achieved by a system for detecting components of the exhaust of moving vehicles. The system of the invention uses more than two beam passes through a detection space in order to generate a signal of sufficient magnitude to overcome the ambient noise in the detection space. Concentrations of one or more exhaust components may be calculated based on a ratio technique in order to render concentrations of one or more exhaust components independent of the absolute magnitude of the detector signal. The system includes a radiation source for producing a beam, optics for guiding the beam through the detection space, and a detector for receiving the beam and generating at least one signal indicative of the absorption of the beam in a wavelength band corresponding to one or more vehicle exhaust components. The system also includes a processor for obtaining information about one or more vehicle exhaust components from the generated signal or signals. 
     The present invention also relates to a method of detecting components in the exhaust of a moving vehicle. The method involves directing radiation through more than two passes through a detection space to a detector whereby the radiation passes through an exhaust plume located in the detection space. The next step is to generate at least one signal responsive to the radiation which passed through the exhaust plume. The at least one signal from the detector may be used to compute a ratio of the amounts of exhaust components. The ratio may be used to provide information about the emissions of a particular vehicle. 
     Other features and advantages of the present invention will be apparent to one of ordinary skill in the art upon reviewing the detailed description of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram of an emission testing system according to one embodiment of the invention. 
     FIG. 2 is a schematic diagram of an emission testing system of a second embodiment of the invention. 
     FIG. 3 is a schematic front view of a vehicle testing lane and emission testing system of a third embodiment of the invention. 
     FIG. 4 is a schematic side view of the vehicle testing lane and emission testing system of FIG. 3 
     FIG. 5 is a schematic of an optical system for use in an embodiment of the invention. 
     FIG. 6 is a schematic diagram of a method in accordance with the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the drawing figures generally, and particularly to FIG. 1, a system for detecting components of the exhaust of a moving vehicle is shown. Analyzer  101  may comprise source  110 , detector  120 , optics  130 , and data processing system  140 . Source  110  may generate a beam  150 . Beam  150  may be projected from source  110  to follow a predetermined path as directed by optics  130 . Optics  130  may be a system of interrelated lenses, reflectors, splitters, filters, or other optical devices for manipulating or directing radiation. Optics  130  direct beam  150  through multiple passes across detection space  160  before directing beam  150  to detector  120 . Detector  120  generates a signal based on the wavelengths of radiation present in the beam. Data processing system  140  may interpret the signal from detector  120 . Data processing system  140  may compute the concentration of one or more components of the vehicle exhaust or may compute ratios indicative of the relative concentrations of two or more exhaust components. 
     Analyzer  101  may be provided in a stationary or mobile vehicle testing lane. Gas analyzer  101  is preferably positioned such that beam  150  makes a plurality of passes through at least a portion of a passing vehicle&#39;s exhaust plume. A plurality of passes may be necessary, in some case, to provide an adequate signal, relative to ambient noise, for determining the relative amounts of compounds present in small quantities in vehicle exhaust, such as CO, NO x , hydrocarbons, and other minor exhaust components. The signal returned by detector  120  may be compared to carbon dioxide, which is typically present in relatively large quantities in vehicle exhaust. In one embodiment, the ratio of one or more exhaust components may be compared to a predetermined threshold for determining whether the vehicle is a high emitter of that component. In another embodiment, data processing system  140  may calculate relative concentrations of one or more exhaust components based on the signals from the detector. The relative gas concentrations may be compared against predetermined emission standards, manually or automatically, and high emitting vehicles can be recognized in this manner. 
     In one embodiment, a highway, off ramp, parking lot, or other driving surface may be used as a vehicle testing lane for analyzer  101 . Analyzer  101  may be set up so that beam  150  crosses a portion of the space above the driving surface substantially orthogonal or perpendicular to vehicle&#39;s direction of travel. When a vehicle&#39;s exhaust plume enters the path of beam  150 , signals from the detector  120  may be used by data processing system  140  to compute the relative amounts of one or more exhaust gases. 
     Analyzer  101  may be permanently or temporarily installed in one or more equipment housings on either side of a vehicle path. In one embodiment, source  110 , detector  120 , data processing means  140 , and some of optics  130  may be installed in a housing on one side of a highway and other optics  130  may be installed on the opposite side of the highway. In another embodiment, components may be installed in a plurality of housings. Preferably, at least the source  110  is contained in a housing which serves to at least partially insulate source  110  from ambient conditions in order to maintain a substantially constant temperature. 
     Source  110  at components may be connected by appropriate connectors, such as wires or a wireless signal transfer system. In another embodiment, some components may be housed in a vehicle, such as a van, to allow easy transportation and redeployment. In one embodiment, analyzer  101  may be mounted on a mobile structure, such as a trailer. A portion of the mobile structure may be a driving surface, preferably an inclined surface. 
     Source  110  produces beam  150 . Beam  150  may be an optical beam of any wavelength of radiation useful in absorption spectroscopy. Source  110  may be any source for generating radiation of the wavelength or wavelengths desired. In one embodiment, beam  150  may comprise ultraviolet and infrared radiation of wavelengths specific to the absorption bands of exhaust components such as CO 2 , CO, NO x , water, hydrocarbons, or other exhaust components. Source  110  may comprise an ultraviolet source and/or an infrared source. Beam  150  may be collimated. Source  110  may produce a collimated beam or may comprise optics for collimating uncollimated radiation produced within source  110 . Source  110  may produce individual beams of a plurality of predetermined wavelengths and may use optics to direct the individual beams into beam  150 . Source  110  may produce a wide range of wavelengths which include the specified wavelengths for exhaust components. Multiple sources may be used. 
     Detector  120  may receive beam  150  and generate a signal indicative of the wavelengths received. In one embodiment, detector  120  comprises one or more sensors recognizing a particular wavelength or range of wavelengths. Detector  120  may comprise optics for splitting, filtering, and directing beam  150  or a portion of beam  150  to the sensors. These detector optics may comprise an optical mechanism for time multiplexing incoming beam  150 . The sensors may generate a signal indicative of the existence and/or intensity of the radiation of the wavelength the sensor receives. Sensors may themselves be sensitive to specific wavelengths or optics, or splitters and filters may be used to direct specific wavelengths to sensors of general sensitivity. Detector  120  may include an array of sensors disposed on a microchip. Detector  120  may be a conventional spectrometer. 
     Multiple detectors may also be used. 
     In one embodiment, Detector  120  is positioned above source  110  on the same side of detection space  160 . Detector  120  may be spaced vertically above driving surface  162  or source  110  may be positioned proximate to driving surface  162 . Detector  120  and source  110  may be situated in other positions relative to each other, detection space  160 , and driving surface  162 . The specific positioning may be determined by the type of source and detector used, the configuration of the optics, and the expected position of exhaust plumes. In any given configuration of the analyzer  101 , the source and detector positions may be interchangeable. 
     Optics  130  may direct beam  150  through multiple passes through detection space  160 . In one embodiment, optics  130  may comprise paired reflectors to reflect beam  150  back and forth across detection space  160 . A first reflector  132  may be positioned on one side of detection space  160  and a second reflector  134  may be positioned on the opposite side of detection space  160 . Beam  150  may be emitted by source  110  toward first reflector  132 . Beam  150  may reflect off of a portion of first reflector  132  toward a portion of second reflector  134 . Beam  150  may then reflect off of the portion of second reflector  134  back toward first reflector  134 . Beam  150  may reflect back and forth across detection space  160 , from first reflector  132  to second reflector  134  one or more times before being directed to detector  120 . Multiple passes of beam  150  increases the likelihood of encountering emissions from a vehicle with a small exhaust plume or for vehicles having their tailpipes at non-standard positions. Multiple passes of beam  150  may encounter an exhaust plume multiple times and may help to increase the signal to noise ratio for generating a useful detector signal. 
     In one embodiment, as shown in FIG. 1, beam  150  makes ten passes across detection space  160 . Beam  150  makes pass  150   a  from source  110  to first reflector  132 . Beam  150  makes pass  150   b  from first reflector  132  to second reflector  134 . Beam  150  makes pass  150   c  from second reflector  134  back to first reflector  132 . Beam  150  makes passes  150   d ,  150   e ,  150   f ,  150   g ,  150   h , and  150   i  as it is reflected back and forth between the two reflectors  132 ,  134 . Beam  150  makes pass  150   j  as it travels from first reflector  132  to detector  120 . In this embodiment, the detection space  160  may be defined as the area approximately between first reflector  132  and second reflector  134 , above driving surface  162 , and below and including the path of pass  150   j . The vertical height and placement of the detection space may vary depending on the location of exhaust ports of the vehicles being analyzed. In a more preferred embodiment for use with motorcycles and similar vehicles, the vertical height of the detection space, as measured from driving surface  162  to the top of pass  150   j , may be about 5 feet or less. Most preferably, the detection space begins about 6 inches off the ground and goes up to a vertical height of about three feet off the ground to thereby accommodate the various types of exhaust systems routinely encountered on vehicles with small engines. Beam  150  may make at least about 2 passes per vertical foot in one embodiment, or about 4 passes per foot in an alternative embodiment. 
     Data processing system  140  may be coupled to detector  120  for receiving signals from detector  120  indicative of the existence and/or intensity of the radiation received by detector  120 . Data processing system  140  may also be coupled to source  110 . Data processing system  140  may use signals received from detector  120  to calculate ratios of one or more exhaust components in order to compensate for dispersion of the exhaust plume. Dispersion may be caused by mixing of ambient air with the exhaust plume, by wind or other ambient conditions, or by the natural process of the exhaust plume spreading out as it leaves the exhaust system. The data processing system  140  of the present invention compensates for various forms of dispersion using the ratio technique explained herein. Data processing system  140  may use signals received from detector  120  to calculate relative concentrations of one or more components of the path of beam  150 . Data processing system  140  may compare the radiation intensity at specific wavelengths produced by source  110  to the radiation intensity at specific wavelengths received by detector  120 . In one embodiment, data processing system  140  may use data from multiple channels, each specific to a particular emission component, to calculate relative concentrations of exhaust species. In one embodiment, data processing system  140  may use data from a continuous range of wavelengths and extract necessary data only on the wavelength or wavelength bands of interest. Data processing system  140  may use signal data to determine the relative concentration of one or more exhaust components based on each component&#39;s detected ratio to carbon dioxide and/or information derived from the stoichiometry of fuel combustion. In one embodiment, data processing system  140  may determine the relative concentration of one or more of the following: CO, CO 2 , HC, NO, NO 2  and water. Data processing system  140  may also calculate relative engine temperature and/or the opacity of the exhaust plume based on signal data. Data processing system  140  need not calculate the total volume of the exhaust plume and need not determine an absolute concentration of the carbon dioxide present in the exhaust plume in order to provide accurate and useful information about various components of the exhaust plume. 
     In one embodiment, data processing system  140  may be part of a computer system for controlling operation of analyzer  101  and peripheral devices. The computer system may control calibration, sampling times, frequency of sampling, timing of sampling, reference sampling, components analyzed, and other aspects of the emissions analysis. The computer system may automatically compare the calculated relative concentrations of one or more components to predetermined emission standards to identify high emitters. Peripheral devices controlled may include video cameras for recording vehicles, license plate readers or other devices for specifically identifying vehicles, devices for detecting vehicle speed and acceleration, display devices and communication devices for relaying calculations and other data, storage devices for storing calculations and other data, and other peripheral devices. 
     FIG. 2 shows an alternate arrangement of an analyzer  201  for a system for remotely detecting components in the exhaust of a moving vehicle. In analyzer  201 , a combination source/detector  210  may be positioned spaced from driving surface  262  at the top of detection space  260 . Combination source/detector  210  may be a combined unit for generating and receiving beam  250 . Combination source/detector  210  may otherwise operate as described above for sensor  110  and detector  120 . Beam  250  is projected from source/detector  210  and guided by optics  230  through detection space  260 . Optics  230  may comprise first reflector  232  on one side of detection space  260  and second reflector  234  on the other side of detection space  260 . Beam  250  may be reflected back and forth between reflectors  232  and  234  in a series of passes before striking reflector portion  236 . In one embodiment, beam  250  may then be reflected by reflector portion  236  back along substantially the same path between reflectors  232  and  234  to source/detector  210 . In another embodiment, beam  250  may be reflected by portion  236  back along a substantially different path between reflectors  232  and  234  to source/detector  210 , such as to make a crisscross pattern. Data processing system  240  may be coupled to source/detector  210  and may operate substantially as described above for data processing system  140 . 
     In a preferred embodiment, shown in FIG. 2, beam  250  makes twenty passes through detection space  260 . Beam  250  makes pass  250   a  from source/detector  210  to first reflector  232 . Beam  250  makes pass  250   b  from first reflector  232  to second reflector  234 . Beam  250  makes pass  250   c  from second reflector  234  back to first reflector  232 . Beam  250  makes passes  250   d ,  250   e ,  250   f ,  250   g ,  250   h , and  250   i  as it is reflected back and forth between reflectors  232  and  234 . Beam  250  makes pass  250   j  as it travels from first reflector  232  to portion  236  of second reflector  234 . Portion  236  reflects beam  250  along substantially the same path beam  250  traveled between reflectors  232  and  234 . Beam  250  makes passes  250   k ,  250   l ,  250   m ,  250   n ,  250   o ,  250   p ,  250   q ,  250   r , and  250   s  as it is reflected back and forth between reflectors  232  and  234  following substantially the same path, in reverse, as passes  250   j ,  250   i ,  250   h ,  250   g ,  250   f ,  250   e ,  250   d ,  250   c , and  250   b . Beam  250  makes pass  250   t  from first reflector  232  to source/detector  210 . The vertical height of detection space  260 , as measured from driving surface  262  to the top of pass  250   a , may be less than 5 feet. Beam  250  may make at least 4 passes per vertical foot. 
     FIGS. 3 and 4 show an embodiment of a system for detecting components in the exhaust of a moving vehicle incorporating an analyzer  301  into a mobile vehicle testing lane  300 . Mobile vehicle testing lane  300  may comprise analyzer  301 , ramp  370 , support structure  380 , and trailer structure  390 . In one embodiment, analyzer  301  may be an gas analyzer as substantially as described above for analyzer  101 . Analyzer  301  may comprise source  310 , detector  320 , optics  330 , and data processing system  340 . Ramp  370  may comprise vehicle driving surface  362 . Analyzer  301  may be supported by support structure  380 . Analyzer  301 , ramp  370 , and support structure  380 , may be mounted on trailer assembly  390 . 
     Source  310  generates a beam  350 . Source  310  may operate substantially as described above for source  110 . Beam  350  may be projected from source  310  and follow a predetermined path as directed by optics  330 . 
     Optics  330  may be a system of reflectors  331 ,  332 ,  333 ,  334 ,  335 ,  336 ,  337 ,  338 , and  339 . Optics  330  may direct beam  350  through multiple passes across detection space  360 . Beam  350  may travel from source  310 , across detection space  360 , to reflector  331 , from reflector  331 , across detection space  360 , to reflector  332 , and so on between the reflectors. Reflector  339  directs beam  350  to detector  320 . The width of detection space  360  measured horizontally between opposed reflectors may be a distance of 3 to 20 feet, more preferably less than 6 feet. A narrow detection space allows more passes with a shorter path length and may make testing lane  300  narrower and more easily transported. Further, a wide detection space may be unnecessary to accommodate small engine vehicles such as motorcycles, mopeds, and other small engine vehicles. 
     Detector  320  may receive beam  350  and generate a signal based on the wavelengths of radiation present in beam  350 . Detector  320  may operate substantially as described above for detector  120 . 
     Data processing system  340  may interpret the signal from detector  320  and compute a relative concentration of one or more components in the path of beam  350 . Data processing system  340  may operate substantially as described above for data processing system  140 . Alternatively, data processing system  340  may not be housed in mobile vehicle testing lane  300 . In one embodiment, data processing system  340  is structurally separate from vehicle testing lane  300  but may be connected to source  310  and detector  320  by a signal transfer device. Signal transfer devices may include wires, wireless signal transfer devices, or other signal transfer devices. In one embodiment, data processing system  340  comprises a computer system for operating analyzer  300  and peripheral devices. 
     Ramp  370  may provide an inclined surface for guiding a vehicle through mobile vehicle testing lane  300 . An inclined driving surface  362  may be provided to increase loading on a vehicle with a small engine in order to increase exhaust plume size or density or to measure emissions from the engine when under load. In one embodiment, ramp  370  may comprise an inclined portion  372  extending through detection space  362  of analyzer  301 , a level portion  374  beyond detection space  362 , and a declined portion to return a vehicle to ground level. 
     Support structure  380  may provide a frame for supporting the components of analyzer  301 . Support structure  380  may provide a first vertical support  382  and a second vertical support  384 . In one embodiment, vertical supports  382  and  384  may support source  310 , detector  320 , and optics  330 . Support structure  380  may be attached to ramp  370  and/or trailer assembly  390 . 
     Trailer assembly  390  allows mobile vehicle emissions testing lane  300  to be easily transported between testing locations. Trailer assembly  390  may comprise wheels and a coupling device for coupling testing lane  300  to a vehicle for transport. In one embodiment, testing lane  300  may have an active configuration for testing vehicle emissions and a transport configuration for transporting testing lane  300 . The transport configuration may comprise folding or detaching portions of ramp  370  and/or securing portions of analyzer  301 . 
     FIG. 5 shows an optical configuration for use in an analyzer, such as analyzers  101 ,  201 , and  301 . FIG. 5 shows a “White” optical system. Radiation in dispersing beam  550   a  issues from source/detector  510 . First spherical mirror  531  refocuses the radiation into converging beam  550   b  directed to second spherical mirror  532 . Second spherical mirror  532  reflects the radiation as dispersing beam  550   c  directed to third spherical mirror  533 . Third spherical mirror  533  refocuses the radiation into converging beam  550   d . Converging beam  550   d  is received by source/detector  510 . White optical systems may allow an extended path length with minimal loss of beam integrity. Rather than attempting to maintain a beam of parallel light along the entire path length from source to detector, White optical systems reflect and refocus the beam on multiple passes through the detection space using spherical mirrors. After the first reflection, there may theoretically be no further geometric radiation loss, only reflective loss. The resulting optical system may have the optical throughput of a short path system with the sensitivity of a long path system. The use of White optical systems may allow longer path lengths, which in turn allow a greater number of passes across a detection area by a single beam. In the laboratory, white cell optics have achieved a path length of 600 meters and may be used to achieve as many as 100 passes across a detection space. 
     FIG. 6 shows a method of detecting gases in the exhaust of a moving vehicle. The method may be practiced using a mobile vehicle emission testing lane substantially as described for FIGS. 3 and 4 above and the testing lane may use an analyzer  101  or  201  as described for FIGS. 1 and 2 above. 
     In step  610 , a vehicle testing lane may be provided. The testing lane may define a detection space, such as detection spaces  160 ,  260 , or  360 . The testing lane may comprise a radiation source for producing a beam, such as sources  110  or  310  or source/detector  210 . The testing lane may comprise optics for guiding the beam through the detection space, such as optics  130 ,  230 , or  330  and may use white cell optics. The testing lane may comprise a detector for receiving the beam, such as detector  120  or  320  or source/detector  210 . The detector may generate an electrical signal indicative of the absorption of the beam in wavelength bands corresponding to carbon dioxide and at least one other vehicle exhaust component. The vehicle testing lane may also comprise a driving surface passing through the detection space, such as ramp  370 . 
     In step  620 , vehicles may be directed through the vehicle testing lane such that the vehicle&#39;s exhaust plume is intersected by the beam on one or more passes. The beam passing through the exhaust plume of the vehicle and being received in the detector may generate an electrical signal in the detector. 
     In step  630 , the ratios of one or more exhaust gases may be calculated. A data processing system, such as data processing systems  140 ,  240 , or  340 , may use ratios based on the electrical signal from the detector to calculate relative concentrations of one or more exhaust components. Neither a volume of the exhaust plume, nor an absolute value of carbon dioxide in the exhaust plume need to be calculated to determine ratios or relative concentrations. 
     In step  640 , the ratios or calculated relative concentrations may be compared to predetermined emissions standards to identify high emitters. This comparison may be made manually or may be made automatically by the data processing system. 
     In step  650 , the owner or operator of the vehicle may be notified of the vehicle&#39;s emission profile and any need for repair or further testing based on emission standards. The agency responsible for administering an inspection and maintenance program may also be notified and emission profiles and comparisons may be stored and compiled. 
     In step  660 , the testing lane may be transported to another testing location. All or part of the testing lane may be built into a vehicle, may be sufficiently mobile to be loaded on a vehicle, or may be mounted to a trailer assembly and trailed behind a vehicle. Some modification of the testing lane may be required for transport. Transportation allows a mobile vehicle testing lane, specifically those for small engine vehicle emissions, to be temporarily operated in a number of locations throughout an urban area. Testing may be held on days when weather encourages the use of motorcycles and mopeds and/or in areas in which such small engine vehicles are common. 
     This invention has been described in connection with the preferred embodiments. These embodiments are intended to be illustrative only. It will be readily appreciated by those skilled in the art that modifications may be made to these preferred embodiments without departing from the scope of the invention as defined by the appended claims.