Conclusions and Implications

The conclusions and lessons learned, presented below, are based on the findings in the Technical Report on the Kentucky CVSA Evaluation (USDOT 2008). Users can refer to the Technical Report for further detail on any conclusions here whose supporting documentation is not given in this Summary Report.

Overall Conclusions and Lessons Learned

The KVE inspectors at Laurel County were not using the ISSES to any great extent during the period of the field study. According to interviews with inspectors and with staff from the KTC, the ISSES hardware was functioning satisfactorily, but the state’s scarcity of resources and staff prevent inspectors from having the time to use the information being displayed by the ISSES. The ISSES was in place and operating at the inspection station, but was not being used to any effective extent during the period of the evaluation.
The portions of the ISSES under evaluation in this study appeared to perform as designed. KVE staff assigned to the Laurel County weigh station, because of their workload and their primary inspection duties, tend to perceive that spending time watching the two ISSES interface screens or monitors is too time-consuming and does not represent an efficient use of their time. The ISSES software and components now deployed—though operational—are considered to be in a development mode as of late 2007.
The vendor informed the evaluation team that the company attempted to use commercial, off-the-shelf technologies for the ISSES whenever possible. While this approach provides advantages with respect to reducing first costs and allowing the state to begin using subsystems like the thermal inspection camera and radiation monitor immediately in a stand-alone mode, it also increases the cost and difficulty of integrating disparate commercial systems.
The deployment took place in a larger enforcement context that has up to now emphasized and rewarded inspectors for the numbers of inspections they complete, not necessarily for achieving high rates of OOS orders. Thus the purpose of the ISSES (to help inspectors focus on the trucks with the worst safety records, and in effect drive upward the rate of OOS orders) is not directly aligned with the traditional goals of the inspectors in Kentucky. This institutional disconnect affected the degree to which the inspectors perceived the ISSES as helping them achieve their personal and organizational job goals.
Lack of training was seen as another obstacle to more effective use of the ISSES. One KVE officer said, “It is a good system but there is no one sitting over the monitors watching the results.”

System Performance Conclusions

The radiation monitor appears to alert inspectors to potential radiation hazards. No attempt was made to simulate radiation-emitting loads to formally test the rates of false positive alarms or false negative (missed detection) alarms. A tendency for nuisance gamma alarms caused by naturally occurring substances, however, has the effect of making inspectors more likely to ignore all of the gamma radiation monitor alarms. As a rule, the KVE inspectors do attend to neutron alarms, which sound different in the scale house and are much fewer in number than the gamma alarms. An isotope identification capability recently deployed at the two newer ISSES stations (Kenton and Simpson) has also reduced the number of nuisance alarms. Data are being collected to develop computer-based “risk matrices” to further limit the number of nuisance radiological alarms in the future.
The thermal inspection device enables inspectors to see potential heat-related defective or malfunctioning equipment that might be missed in a visual review, and archives video data for follow-up review. The effectiveness of the thermal inspection system appears to vary depending on the training, experience, and skills of the operator, especially in synchronizing the views of the ground-level IR/color camera and the gable-mounted color overview camera.
The laser scanner appears to log every truck passing through the ISSES apparatus, but its adjustment is such that the system generates a certain number of extra (blank) records or extra trigger events, which is an impediment to later review of traffic data. For the sample of data reviewed for this evaluation, some gaps in the time synchronization were noted.
The ISSES appears to perform with a minimum of unscheduled downtime. Partly owing to the exposed geographic location of the Laurel County weigh station, the hardware has been subject to several outages caused by lightning strikes and other power drops or interruptions. The system has experienced a low rate of hardware failure, other than some events related to the reliability of electrical power to the site.
Based on experience at the first (Laurel) ISSES site, the location of the visible lighting fixtures was changed from the passenger side to the driver’s side at Kenton to reduce the amount of stray light reaching the mainline of traffic. Also, the Kenton ISSES equipment was positioned approximately twice as far upstream from the scale house as the ISSES equipment at Laurel, in principle allowing Kenton inspectors more time to make decisions based on the system’s output.
As of mid-2007, the system appeared to be at a late stage in the product development cycle, not completely in full-scale production mode, but well beyond the field test prototype stage. It was not yet integrated with any current or historical state or national databases, which affected its usefulness for real-time enforcement applications, but it appeared to be functioning well in stand-alone mode.

Inspection Efficiency Conclusions

A series of scenarios was constructed to compare Kentucky’s current inspection selection methods with various progressive options for integrating ISSES and similar CVISN screening technologies at the state’s weigh stations. The scenarios also explored variations in the inspection selection criteria that states could use in trying to focus their finite resources on the highest-risk carriers, vehicles, and drivers. Substantial potential reductions in crashes, injuries, and fatalities were predicted from wider deployment of ISSES. Estimates were made using statistical modeling.
The roadside enforcement (RE) scenarios were defined as follows:
- RE-0: Random Selection
- RE-1: Baseline—Pre-ISSES/CVISN
- RE-2: Mainline Electronic Screening based on ISS Score
- RE-3: Electronic Screening based on Kentucky OOS Rate Inspection Selection Algorithm
- RE-4: Electronic Screening based on high vehicle and/or driver OOS rates
- RE-5: Electronic screening based on high driver OOS or brake violation rates
- RE-6: Electronic screening based on IR screening and high driver OOS violation rate.
According to the model, current roadside enforcement strategies (RE-1) are responsible for avoiding 126 truck-related crashes, which represents about 4.4 percent of the 2,853 crashes in Kentucky that occur annually, based on 2005 crash statistics. Furthermore, it is estimated that current roadside enforcement activities are responsible for preventing 33 injuries and 2 deaths.
The safety benefits realized increases with each scenario RE-2 through RE-6. The maximum benefit is achieved with RE-6, where 755 crashes (629 more than in the baseline scenario) are avoided if the top 5 percent of vehicles in terms of driver OOS violations are inspected in conjunction with IR screening. This implies that about 26 percent of Kentucky’s 2,853 annual truck-related crashes could be avoided under RE-6. In reality, this figure is an overestimate, because national crash rates were used in the safety benefit calculations, in turn because reliable crash rates for Kentucky were not available.
In terms of injuries and fatalities, the incremental benefits range from 16 to 163 fewer injuries per year, and up to 7 fewer fatalities per year.
To put the crash avoidance numbers into context, consider that the number of large trucks involved in crashes in Kentucky (2,853) is low relative to the 441,000 large trucks involved in crashes nationally, representing only 0.6 percent of national crashes. Also, the percent of Kentucky crashes relative to the number of inspections performed in Kentucky is about 3.3 percent. Comparatively, the national rate of crashes relative to the number of inspections is about 16 percent. Therefore, relative to the number of inspections, Kentucky’s crash rate is smaller than the national crash rate. The exact reason for this is unknown, but possible explanations include a lower volume of traffic in Kentucky, less congested highways, or a smaller number of large cities.
Recalculating the safety benefits achieved when the national number of vehicle and driver inspections in 2005 is used instead of Kentucky inspection figures finds that implementing scenario RE-6 avoids about 6.5 percent of all national crashes.

User Acceptance/Cost Conclusions

As noted above, staffing and training were seen as main barriers to active use of ISSES in everyday KVE inspection operations. The majority of inspectors said ISSES appeared to be user-friendly, and that (compared to the training offered at the Laurel County site), more training is necessary to help them make full use of its capabilities.
Respondents considered most ISSES radiation alarms to be caused by routine, naturally occurring substances (e.g., brick, porcelain, clay) or licensed, placarded medical products. Respondents indicated the radiation monitor needs to be fine-tuned to reduce nuisance alarms. After the time of the user acceptance interviews, the ISSES at the Laurel County site was adjusted to reduce the prevalence of nuisance alarms.
Respondents indicated that they rely on the thermal imaging device with the greatest confidence because they can “actually see trucks on the screen” and believe it enables them to perform their job functions better. It appears to be easy to use, even given little training, and training could only help inspectors make better use of this subsystem.
As for lessons learned from the Laurel County deployment, designers should carefully consider where equipment is sited before installation and obtain input from inspectors. As it is installed now, it appears that the equipment is located too far down the approach ramp from the mainline, at a point that is too close to the scale house. Inspectors need adequate time to interpret information from ISSES and then decide whether to stop a given vehicle.
Deployment teams should provide equipment documentation and user guides along with contact information on-site (e.g., if a radiation alarm goes off) that affords inspectors access to personnel with a working knowledge of equipment. After the time of the user acceptance interviews, contact information for technical support was posted on the ISSES equipment at Laurel County.

Previous | Table of Contents | Next