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64 If both the continuous sampling subsystem and the special 2. An ad hoc special study subsystem intended to address study subsystem are implemented, then the most logical specific questions or roadside safety features. The cases arrangement is to hire a new investigator for each participat- would be selected from both within and outside the CDS ing PSU since the special study cases are mostly sampled out- sample to assure sufficient sample size within a reasonable side of CDS cases. Similarly, new personnel would have to be period of time. In addition to the basic CDS data and the hired at the two Zone Centers to handle the quality control of supplemental field data on roadway and roadside charac- the collected data and coding of additional information for teristics, detailed information would be collected on the the special study. The additional staff at the PSUs and Zone safety device of interest. Again, the cases would be recon- Centers would ensure that the regular CDS operation will not structed to the extent possible to estimate impact condi- be adversely affected. The outside contractor would continue tions and vehicle trajectories. to handle the coding of additional information, reconstruc- tion of the cases, and the performance assessment. The data collection effort is best sponsored by AASHTO and In addition to the training required for the regular CDS data administered through NCHRP. An outside contractor would collection and the continuous sampling subsystem, both PSU be hired to conduct the study and to coordinate the data col- investigators and Zone Center personnel assigned to the spe- lection effort with NASS. A project panel, or a technical advi- cial study data collection effort would require special training sory committee composed of management-level personnel in order to collect and quality control the specific and detailed from the sponsoring agency and NASS, would oversee the data for the special study. The training would be conducted by overall conduct of the study, provide guidance and direction to the outside contractor on data elements, coding instructions, the contractor, and review the study progress and results. and field procedures specific to the special study data collection If only the continuous sampling subsystem is to be imple- effort. The training should include both classroom lectures and mented, then the most logical arrangement is for existing field training as well as on-the-job training. NASS investigators to collect the data since the additional time for the supplemental data would not be sufficient to require new staff. Quality control would be conducted by 5.7 Summary Zone Center personnel. It may be necessary to hire new Zone A long-term data collection plan on single-vehicle, ran-off- Center staff to handle the additional work. Coding of addi- road crashes is proposed. The proposed plan is built around tional information, reconstruction of the cases, and assessment the NASS CDS data collection system, including both within- of the impact performance would be handled by the outside sample supplemental data collection and outside-sample spe- contractor. It is important to make sure that the additional cial studies. The efforts would be prospective in nature, i.e., the work would not adversely affect the regular CDS operation. cases would be sampled from new crashes and consist of two If both the continuous sampling subsystem and the special major subsystems or components: study subsystem are to be implemented, then the most logical arrangement is to hire a new investigator for each participating 1. A continuous sampling subsystem intended for a general PSU. This new investigator would be trained not only in the database to address items of interest pertaining to single- collection of CDS data, but also supplemental data pertaining vehicle, ran-off-road crashes. The cases would be selected to the continuous sampling subsystem and the special study from within the CDS sample and supplement the basic subsystem. Similarly, new personnel would be hired at the two CDS data with additional data on roadway, roadside, and Zone Centers to handle the quality control of the collected data struck-object characteristics. In addition, the cases would and coding of additional information. The completed cases be reconstructed to estimate impact conditions and vehicle would then be forwarded to the outside contractor for addi- trajectories. tional quality control and reconstruction.