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| FHWA > Engineering > Pavements > Research > LTPP > Pooled Fund Studies |
SPS Traffic Pooled Fund Study: Phase I Assessment and Evaluation Reports Executive SummariesAlabama SPS-1 Alabama SPS-1AssessmentA visit was made to the Alabama SPS-1 site on December 10, 2003 for the purpose of conducting an assessment of the WIM system located on US Route 280/431, at milepost 132.15, near Opelika, Alabama. The LTPP lane is the driving lane in the northern direction and is identified as lane number 1 in the WIM controller. This site is not recommended for a site validation until WIM system and pavement remediation repairs have been conducted. The site is instrumented with piezo weighing sensors and a Peek ADR300 WIM Controller. Both piezo WIM sensors failed electronic testing. All other WIM system components are in working order. Sufficient data was collected during the site visit to provide a Sheet 16 for classification verification at this site. There are zero percent-unclassified vehicles. This is below the percentage of 2% defined as the criteria for research data. During classification verification tests performed on site, no vehicles were misclassified or unclassified. The pavement condition is not satisfactory for conducting a performance evaluation. The WIM index was exceeded at all locations. Significant pavement distress was discovered at abandoned WIM array installations immediately preceding the current WIM scale area. Although it could not be visually verified, this distress is suspected to be influencing truck dynamics through the WIM scale area. A review of the speed information collected on-site and provided prior to the visit indicates that the range of truck speeds to be covered during an evaluation is 55 to 65 mph. The posted speed limit at this location is 65 mph. This site has one year of data. There is no validation information available for this site in the traffic database as of June 2003 upload. Based on available information and review of the data submitted through last year, this site still needs 5 years of data to meet the need for 5 years of research quality data. Alabama SPS-5AssessmentA visit was made to the Alabama SPS-5 site on December 9, 2003 for the purpose of conducting an assessment of the WIM system located on US Route 84, at milepost 201, approximately 7 miles west of Dothan, Alabama. The LTPP lane is the driving lane in the eastern direction and is identified as lane number 1 in the WIM controller. This is an amended report following receipt of profile data from the region on January 5, 2004. This site is not recommended for evaluation due to failure of the classification algorithm and errors in speed measurement. The site is instrumented with piezo weighing sensors and a Peek ADR300 WIM Controller. All of the WIM system components appear to be in working order. Sufficient data was collected to provide a Sheet 16 for classification verification at this site. There are zero-percent unclassified vehicles. This is below the percentage of 2% defined as the criteria for research data. However, there is a problem differentiating generally between single unit trucks. There was no pavement distress discovered that would significantly influence truck motions. A review of the speed information collected on-site and provided prior to the visit indicates that the range of truck speeds to be covered during an evaluation is 55 to 65 mph. The posted speed limit at this location is 65 mph. This site has 3 years of data. Based on available information and review of the data submitted through last year, this site still needs 5 years of data to meet the need for 5 years of research quality data. There is no validation information for this site as of June 2003 upload. Alabama SPS-6AssessmentA visit was made to the Alabama SPS-6 site on December 11, 2003 for the purpose of conducting an assessment of the WIM system located on US Interstate 59, at milepost 196.2, approximately 15 miles north of Gadsden, Alabama. This site is not recommended for a site validation due to the failure of the classification algorithm and the speed measurements. The site is instrumented with piezo weighing sensors and a Peek ADR300 WIM Controller. With the exception of the leading piezo sensor, all of the WIM system components are in working order. Sufficient data was collected to provide a Sheet 16 for classification verification at this site. There are zero-percent unclassified vehicles. This is below the percentage of 2% defined as the criteria for research data. However, there is trouble differentiating between Class 4s and Class 5s and Class 4s and Class 6s. The pavement condition appears to be satisfactory. However, the WIM index was exceeded at almost all locations. An AC patch covering the right half of the traveling lane is located from 395 to 523 feet prior to the WIM scale area. Although truck motion in the patched area is significantly influenced, the vehicles appear to stabilize prior to the WIM scale area. A review of the speed information collected on-site indicates that the range of truck speeds to be covered during an evaluation is 60 to 70 mph. The posted speed limit at this location is 70 mph. This site has 1 year of data. Based on available calibration information and review of the data submitted through last year, this site still needs 5 years of data to meet the need for 5 years of research quality data. Delaware SPS-1AssessmentA visit was made to the Delaware SPS 0100 site on October 28, 2003 for the purposes of conducting an assessment of the WIM system located on US 113 South near Ellendale at Mile Post 25.04. This site is not considered a strong candidate for validation. The site is instrumented with WIM piezo and a Peek Model ADR3000 as the controller. The equipment seemed to be in working order, however, adjustments should be made to correct observed operational deficiencies such as speed varying by as much as 5-7 mph from radar collected speed. It was noted that a code of FFCE showed up from time to time, indicating an invalid record. The source of this problem should be determined and corrected. The weights observed on the laptop connected to the ADR3000 seemed to be reasonable, but the data supplied from DelDOT seems to indicate extremely low weights for class 9 vehicles in the LTPP lane (#4, the outside southbound lane). DelDOT stated that they have no unclassified or misclassified vehicles, and that the system automatically assigns them to a pre-determined class. DelDOT did not know what the system used for its default class, nor did they know the parameters for the classification algorithm. There was insufficient information to fully support a Sheet 16 for classification verification. A Sheet 16 has been completed as record of this assessment but the error rates must be considered approximate rather than absolute. The pavement condition is such that it may have a minor contribution to an inability to calibrate the system to obtain research quality data. The WIM sensors are in PCC pavement. There is a slight drop from the asphalt to the PCC pavement surface about 50 feet prior to the first sensor. The asphalt and PCC pavement was in good condition around the WIM sensors. The range of WIM Index values are between 0.27 m/km and 1.27 m/km. While the average values tend to exceed the threshold at which no pavement influence is anticipated to affect weight results, they are not sufficiently large to support any pavement remediation activity. Field observation of trucks concurs with this outcome. A review of the speed information collected on-site/ indicates that the range of truck speeds to be covered during an evaluation is 45 to 55mph. This is lower than actual truck speeds. The measured speeds of trucks for the 15th and 85th percentiles exceed the speed limit of 55 mph. This site has 0 (zero) years of data available through the LTPP program. This site still needs 5 (five) years of data to meet the need for 5 years of research quality data. Delaware SPS-2AssessmentA visit was made to the Delaware 100200 WIM Site on October 29, 2003 for the purpose of conducting an assessment of the WIM system located on Delaware route 113 at milepost 29.27, 4.5 miles south of Milford, Delaware. This site is a rational candidate for validation. Consideration should be given to whether or not the sensors will be replaced to have a greater assurance of 5 years of research quality data before a validation is scheduled. A validation with the current sensors would provide information on quality of any current data that the agency might provide. However, a near term replacement of the sensors without any data being submitted in the interim would make a validation now imprudent. The site is outfitted with a piezo-loop-piezo lane configuration. The sensors are functional, but the low resistance readings observed are probably the result of moisture at the pavement surface. This can contribute to intermittent readings in wet weather. Based on this circumstance and the probable age of the sensors, their replacement should be investigated. There was insufficient information to fully support a Sheet 16 for classification verification. A Sheet 16 has been completed as record of this assessment but the error rates must be considered approximate rather than absolute. The pavement condition is satisfactory for conducting a performance evaluation. The WIM index was exceeded at the right wheel path right shift, which is not thought to have a significant impact on equipment performance. There were no distresses observed that would influence truck motions significantly. A review of the speed information collected on-site indicates that the range of truck speeds to be covered during an evaluation is 45 to55 since traffic speeds generally exceed the posted speed limit of 55 mph. This site has no data in the LTPP database at this time. It still needs 5 years of data to meet the need for 5 years of research quality data. Florida SPS-1AssessmentA visit was made to the Florida SPS-1 site on December 3, 2003 for the purpose of conducting an assessment of the WIM system located on US Route 27, located 13.8 miles south of US Route 80. The LTPP lane is the driving lane in the southern direction and is identified as lane number 4 in the WIM controller. This site is conditionally recommended for a site validation. The site is instrumented with Kistler Quartz weighing sensors. The WIM system utilizes a PAT America DAW-190 WIM Controller. All of the WIM system components are in working order. Sufficient data was collected to provide a Sheet 16 for classification verification at this site. There are one percent-unclassified vehicles. This is below the percentage of 2% defined as the criteria for research data. Class 5 had an error rate of 25% exceeding the threshold 2% of matches for truck classes. The classification verification process will need to be repeated at the next assessment or validation. The State was previously aware of the problem and is taking steps to address this. The pavement condition is satisfactory for conducting a performance evaluation. The WIM Smoothness Index was exceeded on either side of the normal wheelpath. This may have an impact on equipment performance for measuring truck characteristics of vehicle driven on the right-hand or left-hand side of the lane. There were no distresses observed that would influence truck motions significantly. A merge lane 12 feet in width exists directly adjacent to the LTPP lane. It begins approximately 450 feet prior to the WIM scale area, begins to merge with traffic 96 feet following the WIM area, and is completely merged into to mainline 336 feet after the WIM area. This lane does not appear to routinely be used by vehicles for merging, and does not appear to even moderately affect the flow of traffic or the performance of the WIM system. A review of the speed information collected on-site and provided prior to the visit indicates that the range of truck speeds to be covered during an evaluation is 45 to 65 mph. The posted speed limit is 65 mph. This site has 4 years of data. Based on available information and review of the data submitted through this year, this site still needs 5 years of data to meet the requirement for 5 years of research quality data. EvaluationA visit was made to the Florida SPS-1 on December 16 and 17, 2003 for the purposes of conducting a field performance evaluation and calibration of the WIM system located on US 27, 13.8 miles South of SR 80. The site is instrumented with Kistler quartz sensors and PAT DAW190 WIM Controller. The validation used the following trucks:
The overweight on the standard truck was not correctable for the runs conducted for this evaluation. The speeds ranged from 44.0 to 66.0 mph. The temperatures ranged from 61.0 To 89.0 degrees Fahrenheit in the two days of the performance evaluation. The final runs had a temperature range of 61.0 to 73.0 degrees Fahrenheit.
This site fails all LTPP precision requirements except Axle spacing. The failure is due to the wide variation in weights obtained from the WIM equipment. It was observed in the field during the validation, that when the variation was large, the left wheel weight was usually significantly less than the right wheel weight. This is believed most likely to be caused by the sensors not being ground such that they were consistently level or slightly below the adjacent pavement surfaces. Another possible cause could be slight pavement distortions just outside or inside the wheel paths causing the wheels to be oscillating up and down as they rolled across the pavement, applying inconsistent wheel loads to the WIM sensors, depending on transverse location of the wheels, and possibly related to vehicle speed. The agency did all computations for factor adjustments and made all equipment changes. This was expected given the information on the Traffic Sheet 18 completed as part of the assessment visit held on December 3, 2003. The following remedial actions are recommended so that this site may meet LTPP precision requirements. First, to grind the sensors to the manufacturer's specifications and then re-try the calibration/validation process and see if that eliminates the problems. If that does not correct the problem, then the second recommendation would be to grind the pavement to smooth out the problems indicated in profile/WIM Profile Index. Should this action be required, reinstallation of one or both of the sensors may be necessary. The correction of the classification algorithm identified during the assessment is still outstanding. Florida SPS-5AssessmentA visit was made to the Florida SPS-5 site on December 4, 2003 for the purpose of conducting an assessment of the WIM system located on US Route 1, located 4.5 miles north of State Route 706. The LTPP lane is the driving lane in the southern direction and is identified as lane number 4 in the WIM controller. This site is conditionally recommended for a site validation. The site is instrumented with Kistler Quartz weighing sensors. The WIM system utilizes a PAT America DAW-190 WIM Controller. All of the WIM system components are in working order. Sufficient data was collected to provide a Sheet 16 for classification verification at this site. There are two-percent unclassified vehicles. This is the limiting percentage defined as the criteria for research data. Class 5s had an error rate of 35 % exceeding the threshold of 2% of matches missed for truck classes. The classification verification needs to be repeated during the next assessment or validation whether or not the algorithm is modified. The agency is aware and is currently working on the classification issue. The pavement condition is satisfactory for conducting a performance evaluation. The WIM index was exceeded at three locations none of which are thought to have a significant impact on equipment performance as they are at the rightmost edge of the lane. There were no distresses observed that would influence truck motions significantly. A review of the speed information collected on-site and provided prior to the visit indicates that the range of truck speeds to be covered during an evaluation is 45 to 55 mph. The posted speed limit is 55 mph. This site has 10 years of classification data and 9 years of weight data. Based on available information and review of the data submitted through last year, this site still needs 5 years of weight data to meet the need for 5 years of research quality data. This site does not have validation information as of the June 2003 upload. EvaluationA visit was made to the Florida SPS-5 on December 18, 2003 for the purpose of conducting a field evaluation/calibration of the WIM system located on US Route 1, 4.5 miles North of SR 706. The site is instrumented with Kistler quartz sensors and PAT DAW190 WIM Controller. The validation used the following trucks:
The speeds ranged from 44 to 56 mph. The temperatures ranged from 71.5 to 86.5 degrees Fahrenheit.
This site meets all LTPP precision requirements except speed, which is not considered sufficient to disqualify the site as having research quality data for weight information. The classification algorithm however has yet to be corrected and thus the classification information cannot be considered of research quality. The agency did all computations for factor adjustments and made all equipment changes. This was expected given the information on the Traffic Sheet 18 completed as part of the assessment visit held on December 4, 2003. The pavement condition was satisfactory for conducting a performance evaluation. There were no distresses observed that would influence truck motions significantly. A visual survey determined that there is no discernible bouncing or avoidance by trucks in the sensor area. Profile data was collected Fugro BRE, Inc., on November 12, 2003. The WIM index was exceeded at 3 locations, none of which had a significant impact on equipment performance. There are no immediate remedial actions required to improve the precision of the weight data. The correction of the classification algorithm identified during the assessment is still outstanding. Ohio SPS-1AssessmentA visit was made to the Ohio SPS-1 site on November 12th, 2003 for the purposes of conducting an assessment of the WIM system located on US Route 23 southbound at milepost 19.7. The roadway across the site was closed and prevented obtaining of all the necessary information to support a recommendation for evaluation. This site is not recommended for a site validation. The average pavement index values exceed the threshold at which the smoothness of the pavement is expected to have no impact on equipment performance. There has been no direct observation of trucks across the WIM section (due to the lane closure). There has been no verification of the speed or classification output for this lane. The WIM controller is used for the sensors at this site and at the SPS-2 site. Sensors at both locations are load cells. All electrical and electronic equipment appears to be in working order. A visual inspection of the site discovered that the drainage area for the load cells is inadequate and needs to be improved. The software functionality could not be checked due to lack of traffic across the sensors. There is no data to support a Sheet 16 for classification verification. A visual survey of truck movement over the site could not be performed due to the rerouting of traffic. A review of the speed information collected from the rerouted traffic on-site indicates that the range of truck speeds to be covered during an evaluation is 45 to 55 mph. Traffic speeds are expected to be independent of the actual roadway used on this route. The pavement appears to be in a good condition except for the faulting at the transition of asphalt concrete pavement to cement concrete pavement 165 feet prior to the sensors. The LTPP WIM index thresholds for both SRI and LRI for the wheel path and runs to the right and left of it all exceed the threshold currently used to determine the impact of smoothness on equipment performance. This site has 3 years of historical data. Based on available information and review of the data submitted through last year, this site still needs 5 years of data to meet the need for 5 years of research quality data. There is no validation information in the LTPP database for this site as of June 2003 upload. The available historical traffic data for 1998 is significantly different from 2000 and 2001. In order to consider the 1998 data as potentially of research quality for the site, additional investigation is required. Ohio SPS-2Assessment ReportA visit was made to the Ohio SPS-2 site on November 12th, 2003 for the purpose of conducting an assessment of the WIM system located on US Route 23 northbound at milepost 19.7. The equipment is also used for the SPS-1 site in the southbound lanes at the same location. The site is instrumented with Mettler-Toledo load cells and controller. The equipment is in working order. However, adjustments are needed to the speed measurements and potentially the classification algorithms. This site is not recommended for a site validation. The site has large errors in the classification algorithm for trucks other than Class 9s. The speed and axle spacings are significantly beyond LTPP precision requirements. More than 80 percent of the LTPP WIM Index values exceed the threshold at which there is no expected impact on equipment outputs. Sufficient data was collected to provide a Sheet 16 for classification verification at this site. There are 0 percent unclassified vehicles. This is below the percentage of 5% defined as the criteria for research data. The following truck classes had an error rate exceeding 2% of matches: Class 4, Class 5, Class 6 and Class 8. The algorithm for classification should be reviewed and the classification verification repeated at the next assessment or evaluation. The pavement condition is satisfactory for conducting a performance evaluation. There were no distresses observed that would influence truck motions significantly. A visual survey of truck movement over the site determined that there is no discernible vertical or horizontal movement of the trucks prior to, passing over, or beyond the WIM scale area. The WIM index was exceeded at 80 percent of the locations. The site does not meet LTPP smoothness requirements. A review of the speed information collected on-site indicates that the range of truck speeds is 50 to 60 mph. With a speed limit of 55 mph the range for validation will be limited to 45 to 55 mph. This site has 3 years of data. Based on available information and review of the data submitted through last year, this site still needs 5 years of data to meet the need for 5 years of research quality data. The February and March 1998 data is bad but its removal will not affect the inclusion of that year when a determination is made on nominal research quality. There is no validation information in the LTPP database for this site as of June 2003 upload. Ohio SPS-8AssessmentA visit was made to the Ohio SPS-8 site on November 13, 2003 for the purpose of conducting an assessment of the WIM system located on Norton-Waldo Road, approximately 0.16 miles south of State Route 229. This site can be considered for a site validation. It has low truck volumes and so most assessment measures cannot be evaluated without the number of truck runs generated by a validation. The pavement does not meet WIM smoothness requirements but the actual impact of the current smoothness cannot be effectively determined without running trucks across the pavement. The site is instrumented with MSI Bare flat piezo sensors and a Peek ADR-2000 WIM controller. The equipment is in working order, however, there is no temperature compensation installed. The pavement condition is satisfactory for conducting a performance evaluation. The smoothness thresholds were exceeded at virtually all locations in the section. There were no distresses observed that would influence truck motions significantly. A very limited (five trucks in three hours) visual survey of truck movement over the site determined that there is no discernible vertical or horizontal movement of the trucks prior to, passing over, or beyond the WIM scale area. A review of the speed information collected on-site indicates that the 15th and 85th percentile speed limits are 35 mph and 50 mph respectively. There is no readily observable posted speed limit on this road. From the information obtained from the State about roads of this general type we recommend the range of truck speeds to be covered during an evaluation to be between 25 and 35 mph. This may be revised in further consultation with the agency. This site has a data sample whose volumes and distributions are inconsistent with the assessment observations. There is no validation information in the LTPP database for this site as of June 2003 upload. This is an environmental impacts study section. For these sections where minimal truck loading can be verified through a year's worth of weight data, data collection can be reduced to classification information only. The five-year weight data requirement may potentially be waived. Pennsylvania SPS-6AssessmentA visit was made to the Pennsylvania SPS 6 site on November 6th, 2003 for the purposes of conducting an assessment of the WIM system located on US Interstate 80 at milepost 151. This site is currently not a candidate for a field performance evaluation and calibration. The site is instrumented with two, half-lane, MSI piezo sensors in a staggered array and a PAT America DAW100 controller. The equipment is not in working order. The following actions will be needed to make the equipment fully operational:
There was insufficient data to support a Sheet 16 for classification verification. This will need to be part of the next assessment or evaluation. The pavement condition is such that it may contribute to an inability to calibrate the system to obtain research quality data. The range of WIM Index values are between 0.48 and 2.27. The higher values are associated with possible problems in the immediate vicinity of the sensors. A reevaluation of the site smoothness after repair is suggested as replacement may involve relocation or pavement remediation. Among the distresses observed that influence truck motion is a transverse dip in the pavement approximately 161 feet before the leading WIM sensor, low severity rutting and medium severity longitudinal (environmental) cracking. A review of the speed information collected on site indicates that the range of truck speeds to be covered during an evaluation is 45 and 65 mph (Posted speed limit at this site is 65 mph). This site has 4 years of historical data. Between 1993 and 2001 all loading data is effectively sampled rather than continuous. Based on available calibration information and review of the data submitted through last year, this site still needs 5 years of data to meet the LTPP requirement for five years of research quality data. Due to the lack of landline communication accessibility, and the recommendation of the FHWA for AC power and PCC pavement for all WIM sites, the relocation of the WIM site to a new location was investigated during the assessment. The relocation of the site was deemed unfeasible due to median restrictions (width and wooded areas), and the continued lack of AC power and landline communication services accessible within a 5- mile radius of the present site location. Relocation further from the site should be supported by a Truck O-D survey to verify that the weighed traffic stream is in fact essentially the same trucks as are crossing the LTPP sections. If it is determined that reinstallation of WIM is not appropriate, every effort should be made to have a working classification system at this location for the remaining life of the SPS project. Tennessee SPS-6AssessmentA visit was made to the Tennessee SPS-6 site on November 18, 2003 for the purposes of conducting an assessment of the WIM system located on US 40 at milepost 91.67. This site is not recommended for a site validation. The site is instrumented with a PAT America DAW-100 WIM controller. The in-road sensors were installed in the westbound outside lane but were removed during a milling and overlay operation conducted in summer of 2003. This site has an asphalt overlay over Portland cement concrete. There is no data to support a Sheet 16 for classification verification. This will need to be a part of the next assessment or evaluation. The pavement condition is satisfactory for conducting a performance evaluation if the WIM sensors are installed. The WIM index was not exceeded at any location except one. There were no distresses observed that would influence truck motions significantly. A visual survey of truck movement over the site determined that there is no discernible vertical or horizontal movement of the trucks prior to, passing over, or beyond the WIM scale area. The movement of the trucks after the sensors are installed may or may not change. A review of the speed information collected on-site indicates that the range of truck speeds that should be covered during an evaluation is 60 to 70 mph. With a posted speed limit of 65 the recommended speeds are 55, 60 and 65 mph. This site has only 2 years of limited classification data and a 1-year sample of weight data. Based on available information and review of the data submitted through last year, this site still needs 5 years of data to meet the need for 5 years of research quality data. Without validation or calibration information due to the small data size and with the sensor removed this data cannot even be evaluated for nominal research quality. This site does not have validation information as of June 2003 upload in the LTPP traffic database. Texas SPS-1Validation ReportA visit was made to the Texas SPS 480100 beginning on April 26 and continuing through April 28, 2005 for the purposes of conducting a Validation of the WIM system located on US 281 (9.1 miles (14.6 km) north of State Route 186), near Edinburg, TX. The validation procedures were in accordance with LTPP’s Data Collection Guide dated August 31, 2001. The site is instrumented with PAT bending plate and loop sensors with DAW-190 electronics. The agency is utilizing the Texas-VI classification scheme for this sensor set, while utilizing a modified FHWA 13-bin classification scheme for the 0199 site sensors. This site was installed in February 2005 as part of the relocation and replacement of the WIM System sensors and equipment for the SPS 0100 site. The sensors are installed in the southbound direction approximately 800 feet (244 m) south of the original site. The controller identifies this as Lane #4. Along with the instrumentation of the LTPP lane, the State also instrumented the other southbound lane as well as the two northbound lanes at this location. They also installed Kistler quartz piezo sensors in the LTPP lane approximately 11 feet (3.35 m) south of the trailing edge of the last bending plate sensor for this lane (This equipment is identified as SPS 480199 and was validated as an additional lane). The WIM controller is housed in shared cabinet along with the controller for the 0199 site. The sensors were installed in newly constructed portland concrete cement which was ground for smoothness prior to the installation. This site meets all LTPP loading precision requirements except speed, which is not considered sufficient to disqualify the site as having research quality data. This site meets the overall classification requirement of less than two percent unclassified. However, it does not meet the less than two percent trucks misclassified criteria. The classification algorithm currently in use is not providing research quality classification data. The validation used the following trucks:
The validation speeds ranged from 60 to 73 miles per hour (96.6 to 117.5 km per hour). The site is currently posted with a speed limit of 70 miles per hour (112.7 km per hour). The pavement temperatures ranged from 93 to 115 degrees Fahrenheit (33.9 to 46.1 degrees Celsius).
The pavement condition appeared to be satisfactory for conducting a performance evaluation. There were no distresses observed that would influence truck motions significantly. A visual survey determined that there is no discernable bouncing or avoidance by trucks in the sensor area. If this site had been evaluated using ASTM E-1318-02 it would have met the conditions for a Type I site exclusive of wheel loads. LTPP does not validate WIM performance with respect to wheel loads, and the field validation procedures do not include verification of that information.
2. Texas SPS 1 - Additional LaneValidation ReportA visit was made to the Texas SPS-1 site beginning on April 26 and continuing through April 28, 2005 for the purposes of conducting a Validation of the WIM system located on US Route 281, located approximately 9.1 miles (14.6 km) north of State Route 186, near Edinburg, TX. The validation procedures were in accordance with LTPP’s SPS WIM Data Collection Guide dated August 21, 2001. This site is designated as 0199, the second set of operational sensors installed at this location. The site is instrumented with Kistler quartz piezo sensors installed in Portland concrete cement and ECM Micro Hestia electronics. The sensors are installed in the southbound direction approximately 11 feet (3.35 m) south of the trailing edge of the PAT bending plate sensor for the SPS-1 site. The controller identifies this as Lane #4. While the bending plate sensors were installed in all lanes at this location, only the LTPP lane was instrumented with the Kistler quartz piezo sensors. The agency uses a modified FHWA 13-bin classification scheme for this set of sensors, while utilizing the Texas VI classification scheme for the 0100 site. The modification utilizes a Class 99 for unknown vehicles. This site was installed in February 2005 as part of the relocation and replacement of the WIM System sensors and equipment for the SPS 0100 site. The WIM controller is housed in shared cabinet along with the controller for the 0100 site. The sensors were installed in newly constructed portland concrete cement which was ground for smoothness prior to the installation. This site meets all LTPP loading precision requirements except speed, which is not considered sufficient to disqualify the site as having research quality data. This site meets the overall classification requirement of less than two percent unclassified. It does not meet the less than two percent misclassified criteria. The classification algorithm is currently not providing research quality classification information. Most vehicles that were misclassified were Class 3s, 4s and 5s that were being misidentified within the category of light single unit vehicles, i.e. 3s classified as 4s and 5s, 4s being classified as 5s, and 5s being classified as 3s and 4s. This misclassification failure is not considered significant under the proposed modification to the definition of research quality classification data (by the Traffic ETG) that includes only heavy vehicles (Class 6 and above). The validation used the following trucks:
The validation speeds ranged from 58 to 70 miles per hour (93 to 112.7 km per hour). The site is currently posted with a speed limit of 70 miles per hour (112.7 km per hour). The pavement temperatures ranged from 93 to 115 degrees Fahrenheit (33.9 to 46.1 degrees Celsius) during the validation runs.
The pavement condition appeared to be satisfactory for conducting a performance evaluation. There were no distresses observed that would influence truck motions significantly. A visual survey determined that there is no discernable bouncing or avoidance by trucks in the sensor area. If this site had been evaluated using ASTM E-1318-02 it would have met the conditions for a Type I site exclusive of wheel loads. LTPP does not validate WIM performance with respect to wheel loads, and the field validation procedures do not include verification of that information.
MACTEC field staff worked with vendor representatives to compute weight compensation factor adjustments. The vendor representative under the direction of the agency representative made all equipment changes. 3. Texas SPS-1Validation Report -- Lanes 1, 2 & 3A visit was made to the Texas SPS-1 site beginning on April 26 and continuing through April 28, 2005 for the purposes of conducting a Validation of the WIM system located on US Route 281, approximately 9.1 miles (14.6 km) north of State Route 186, near Edinburg, TX. In conjunction with this visit, at the request of the Texas Department of Transportation, validations of the weight estimates for the other three lanes, which contribute to AADT estimates, were also conducted. The validation procedures were generally in accordance with LTPP’s SPS WIM Data Collection Guide dated August 21, 2001. The site is instrumented with PAT bending plate and loop sensors in each lane and is controlled by a single DAW-190 unit. The agency is utilizing the Texas-VI classification scheme for these sensor sets. While formal classification verification was not performed on Lanes 1, 2 and 3, the same problems that are documented in our LTPP Lane report were observed for these lanes. This site was installed in February 2005 as part of the relocation and replacement of the WIM System sensors and equipment for the SPS-1 site. Along with the instrumentation of the LTPP lane, the State also instrumented the other southbound lane as well as the two northbound lanes at this location. They also installed Kistler quartz piezo sensors in the LTPP lane approximately 11 feet (3.35 m) south of the trailing edge of the last bending plate sensor for this lane (This equipment is identified as SPS 480199 and was validated as an additional lane). The WIM controller is housed in a shared cabinet along with the controller for the 0199 site. The sensors were installed in newly constructed portland concrete cement which was ground for smoothness prior to the installation. The site is currently posted with a speed limit of 70 miles per hour (112.7 km/hr). The lanes were identified in the WIM controller as follows;
All of the additional lanes were validated and met the LTPP loading precision requirements except speed measurements, which are not considered sufficient to disqualify the site as having research quality data. The validation, calibration and subsequent testing used the following trucks:
The pavement condition appeared to be satisfactory for conducting a performance validation. The movement of the test trucks while they traversed the WIM scale approach, weighing and exit areas was observed. Modest bouncing was observed in Lane 1. The movement occurred approximately 300 feet (91.4 m) prior to the scale area and the trucks appeared to stabilize prior to crossing the WIM scales. There did not appear to be any apparent movement of the trucks for Lanes 2 & 3. The trucks appeared to travel down the center of each lane and daylight was not visible between the tires and the sensors. |
More InformationEventsContactsDeborah Walker Customer Service |
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This page last modified on 06/05/06 |
