The National Academies Press

Currently Skimming:

Pages 10-25

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.

From page 10... ... These data elements will require reconstruction of the crashes. The data collection plan presented in this chapter covers the data elements requiring supplemental field data collection and reconstruction. Read the entire page →
From page 11... ... 11 Variable Availability Case Screening Criteria Area type - PSU 1 Crash type - Single-vehicle, ran-off-road crashes 1 Vehicle type - Passenger vehicles only 1 Completeness of data on key variables 1 Injury severity - Serious and fatal injury 1 Variables of Primary Interest: Encroachment conditions at point of departure - Action prior to leaving travelway 1 - Speed 3 - Angle 3 Pre-impact vehicle trajectory - Vehicle path 3 - Maximum lateral extent of encroachment 3 - Total longitudinal distance 3 General impact data - Impact sequence 1 - Object struck 1 - Rollover occurrence 1 - Post-impact trajectory 3 Impact conditions – first harmful event - Impact speed 3 - Impact angle 3 - Vehicle orientation 3 Impact conditions – most harmful event - Impact speed 3 - Impact angle 3 - Vehicle orientation 3 Driver action - Evasive action 1 - Steering – vehicle path 3 - Braking 3 Controlling Variables: Highway type - Functional class 2 - Roadway type 1 - Speed limit 1 Travelway characteristics - Number of lanes 2 - Lane width 2 - Horizontal curvature - Point of departure and maximum 2 - Vertical grade - Point of departure and maximum 2 Roadside characteristics - Shoulder type and width 2 - Roadside slopes – widths and rates of slopes 2 - Median type, width, and slope 2 Traffic characteristics - ADT 2 - Percent truck 2 Struck object characteristics - Object type 2 - Impact performance 3 Vehicle characteristics - Type 1 - Make and model 1 - Curb weight 1 - Vehicle damage 1 - Occupant compartment deformation and intrusion 1 Highest occupant injury severity - Abbreviated Injury Scale (AIS) 1 - Police Injury Code (PIC) Read the entire page →
From page 12... ... This approach can be implemented within a short period of time since it involves only existing NASS CDS cases. Supplemental field data collection protocol and manual review Variable Availability Variables of Secondary Interest: Time - Day of week 1 - Time of day 1 Environmental conditions - Light 1 - Weather 1 * Read the entire page →
From page 13... ... This third alternative of retrospective supplemental field data collection and manual review and reconstruction of existing NASS CDS cases was, therefore, selected for this study. However, it should be noted that NHTSA had changed its policy, starting with the 2003 data, to keep police accident reports in the file for only one year. Read the entire page →
From page 14... ... , and sport utility vehicles, 198 (16.56%) Read the entire page →
From page 15... ... Passenger cars accounted for about 65% for both the eligible and sampled cases. The proportions of sport utility vehicles and vans/minivans decreased somewhat for the sampled cases while the percentage of pickup trucks increased. Read the entire page →
From page 16... ... Eligible, complete, and sampled cases by primary sampling unit. Unweighted Weighted Abbreviated Injury Scale Number Percentage Number Percentage N o Injury (0) Read the entire page →
From page 17... ... 3.4.2 Supplemental Field Data Collection Data elements requiring supplemental field collection are shown in Table 10. The protocol for the supplemental field data collection effort was developed, including the field forms and the accompanying coding and instruction manuals. Read the entire page →
From page 18... ... • Driver input -- steering and/or braking Encroachment conditions at point of departure - Speed - Angle Pre-impact vehicle trajectory - Vehicle path - Maximum lateral extent of encroachment - Total longitudinal distance General impact data - Post-impact trajectory Impact conditions – first harmful event - Impact speed - Impact angle - Vehicle orientation Impact conditions – most harmful event - Impact speed - Impact angle - Vehicle orientation Driver action - Steering – vehicle path - Braking Table 11. Data elements requiring reconstruction. Read the entire page →
From page 19... ... Vehicle Heading Angle at Final Rest The completed case, including data from the regular NASS CDS data collection, the supplemental field data collection, and the manual review and reconstruction, was then sent to the project staff for final quality control and reconstruction to estimate the impact speeds. 3.4.4 Reconstruction of Impact Speed As mentioned above, the completed cases from KLD Associates went through one final quality check by the project staff to assure completeness and accuracy. Read the entire page →
From page 20... ... • Data elements that are not documented. The two areas where existing NASS CDS cases may not contain sufficient information are elevation changes along the vehicle path and the characteristics and sustained damage of the impacted roadside feature(s) Read the entire page →
From page 21... ... Brief discussions on reconstruction procedures for the various roadside features are presented in the following sections. 3.4.4.1 Pole Support Structures A computerized reconstruction procedure was developed for ran-off-road crashes involving pole support structure, including breakaway and nonbreakaway utility poles, luminaire supports, and sign supports (25) Read the entire page →
From page 22... ... Where possible, procedures for estimating energy losses during vehicle rollover formed the basis for reconstructing rollover crashes associated with culvert accidents. Conventional trajectory analyses were used whenever the vehicles remained upright after striking the culvert. Read the entire page →
From page 23... ... Other data elements were found to have been poorly recorded on the supplemental data forms. For example, in some cases, the roadside slope was recorded as the highway grade. Read the entire page →
From page 24... ... 17.20 11.90 0.60 16.90 10.20 0.47 0.70 IS value kJ 41.70 59.60 3.02 36.90 74.90 3.41 0.31 Degree of curvature deg. 2.27 7.50 2.65 2.65 6.72 0.32 0.45 Driver action 3.92 3.03 0.15 4.16 3.09 0.15 0.27 Month 6.68 3.45 0.17 6.39 3.00 0.14 0.20 Access control 2.27 0.92 0.05 2.28 0.94 0.04 0.82 Accident time 0.48 0.30 0.02 0.52 0.40 0.02 0.10 Alignment 1.53 0.79 0.04 1.61 0.80 0.04 0.17 Curb height mm 5.59 29.23 1.48 8.24 39.31 1.86 0.27 Curbs 0.09 0.40 0.02 0.08 0.36 0.02 0.64 Departure side 1.49 0.50 0.03 1.43 0.50 0.02 0.07 Divided/undivided 1.43 0.50 0.03 1.38 0.49 0.02 0.14 Grade % 1.50 1.67 0.08 1.39 1.49 0.07 0.10 Highway speed limit mph 57.45 9.24 0.47 55.68 9.44 0.43 0.006 Land use 1.76 0.43 0.02 1.70 0.47 0.02 0.06 Lane width m 3.69 0.55 0.03 3.64 0.52 0.02 0.18 Lat distance from departure to rest m 0.07 13.45 0.68 1.24 13.22 0.60 0.20 Lateral travel m 0.37 12.22 0.62 1.02 12.93 0.59 0.45 Heading angle at point of rest deg. Read the entire page →
From page 25... ... Users should use caution whenever using the combined database to examine highway or crash characteristics that are close to the threshold of statistical significance. 3.6 Relational Database The design of a relational database for the purpose of storage and retrieval of crash data was developed and implemented. Read the entire page →

From page 10...

... These data elements will require reconstruction of the crashes. The data collection plan presented in this chapter covers the data elements requiring supplemental field data collection and reconstruction.