DOT 23 CFR PART 1340-2011 UNIFORM CRITERIA FOR STATE OBSERVATIONAL SURVEYS OF SEAT BELT USE.pdf

1、572 23 CFR Ch. III (4111 Edition) Pt. 1340 (2) Administer the funds in accord-ance with 49 CFR part 18 and OMB Cir-culars A102 and A87; and (3) Maintain its aggregate expendi-tures from all other sources, except those authorized under Chapter 1 of Title 23 of the United States Code, for highway safe

2、ty data and traffic records programs at or above the average level of such expenditures in Federal fiscal years 1996 and 1997 (either State or fed-eral fiscal year 1996 and 1997 can be used). 63 FR 54048, Oct. 8, 1998, as amended at 65 FR 48911, Aug. 10, 2000 PART 1340UNIFORM CRITERIA FOR STATE OBSE

3、RVATIONAL SUR-VEYS OF SEAT BELT USE Sec. 1340.1 Purpose. 1340.2 Applicability. 1340.3 Basic design requirements. 1340.4 Population, demographic, and time/ day requirements. 1340.5 Documentation requirements. APPENDIX A TO PART 1340SAMPLE DESIGN AUTHORITY: 23 U.S.C. 157; delegation of au-thority at 4

4、9 CFR 1.50. SOURCE: 63 FR 46392, Sept. 1, 1998, unless otherwise noted. EFFECTIVE DATE NOTE: At 76 FR 18056, Apr. 1, 2011, part 1340 was revised, effective May 2, 2011. For the convenience of the user, the re-vised text is set forth following the text cur-rently in effect. 1340.1 Purpose. This part

5、establishes uniform criteria for surveys of seat belt use conducted by States under 23 U.S.C. 157. 1340.2 Applicability. These uniform criteria apply to State surveys of seat belt use, beginning in calendar year 1998 (except as otherwise provided in this part), and continuing annually thereafter thr

6、ough calendar year 2001. 1340.3 Basic design requirements. Surveys conducted in accordance with this part shall incorporate the fol-lowing minimum design requirements: (a) Probability-based requirement. The sample identified for the survey shall have a probability-based design such that estimates ar

7、e representative of safety belt use for the population of in-terest in the state and sampling errors may be calculated for each estimate produced. (b) Observational requirement. Min-imum requirements include the fol-lowing: (1) The sample data shall be collected through direct observation of seat be

8、lt use on roadways within the State, con-ducted completely within the calendar year for which the seat belt use rate is being reported; (2) Seat belt use shall be determined by observation of the use or non-use of a shoulder belt; (3) Observers shall be required to fol-low a predetermined, clear pol

9、icy in the event that observations cannot be made at an assigned site at the speci-fied time (due to heavy rain, construc-tion, safety problems, etc.); (4) Instructions to observers shall specify which road and which direction of traffic on that road are to be ob-served (observers must not be free t

10、o choose between roads at an intersec-tion); and (5) Observers shall follow clear in-structions on how to start and end an observation period and how to stop and start observations if traffic flow is too heavy to observe all vehicles or if vehi-cles begin moving too quickly for ob-servation (to remo

11、ve any possible bias, such as starting with the next belted driver). (c) Precision requirement. The relative error (standard error divided by the es-timate) for safety belt use must not ex-ceed 5 percent. 1340.4 Population, demographic, and time/day requirements. Surveys conducted in accordance with

12、 this part shall comply with the following minimum population, demo-graphic, and time/day requirements: (a) Population of interest. (1) Drivers and front seat outboard passengers in passenger motor vehicles (passenger cars, pickup trucks, vans, and sport utility vehicles) must be observed in the sur

13、vey. (Only overall restraint use for the population of interest is re-quired. However, in order to assist in the evaluation of trends, it is rec-ommended that data be collected in VerDate Mar2010 09:39 May 11, 2011 Jkt 223076 PO 00000 Frm 00582 Fmt 8010 Sfmt 8010 Y:SGML223076.XXX 223076wwoods2 on DS

14、K1DXX6B1PROD with CFRProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-573 National Highway Traffic Safety Admin., DOT Pt. 1340, App. A such a way that restraint use estimates can be reported separately for pas-senger cars and other covered vehicles, a

15、nd separately for drivers and front- seat outboard passengers within those vehicle groups.) (2) Surveys conducted during cal-endar year 1998 shall be deemed to com-ply with paragraph (a)(1) of this section if passenger motor vehicles registered in-State are included in the survey. For surveys conduc

16、ted during calendar year 1999 and thereafter, passenger motor vehicles registered both in-state and out-of-state must be included in the survey. (b) Demographics. Counties, or other primary sampling units, totaling at least 85 percent of the States popu-lation must be eligible for inclusion in the s

17、ample. States may eliminate their least populated counties, or other pri-mary sampling units, to a total of fif-teen percent or less of the total State population, from the sampling frame. (c) Time of day and day of week. All daylight hours for all days of the week must be eligible for inclusion in

18、the sample. Observation sites must be ran-domly assigned to the selected day-of- week/time-of-day time slots. If obser-vation sites are grouped to reduce data collection burdens, a random process must be used to make the first assign-ment of a site within a group to an ob-servational time period. Th

19、ereafter, as-signment of other sites within the group to time periods may be made in a manner that promotes administra-tive efficiency and timely completion of the survey. 63 FR 46392, Sept. 1, 1998, as amended at 65 FR 13683, Mar. 14, 2000 1340.5 Documentation requirements. All sample design, data

20、collection, and estimation procedures used in State surveys conducted in accordance with this part must be well docu-mented. At a minimum, the docu-mentation must: (a) For sample design (1) Define all sampling units, with their measures of size; (2) Define what stratification was used at each stage

21、of sampling and what methods were used for allocation of the sample units to the strata; (3) Explain how the sample size at each stage was determined; (4) List all samples units and their probabilities of selection; and (5) Describe how observation sites were assigned to observation time peri-ods. (

22、b) For data collection (1) Define an observation period; (2) Define an observation site and what procedures were implemented when the observation site was not ac-cessible on the date assigned; (3) Describe what vehicles were ob-served and what procedures were im-plemented when traffic was too heavy

23、to observe all vehicles; and (4) Describe the data recording proce-dures. (c) For estimation (1) Display the raw data and the weighted estimates; (2) For each estimate, provide an es-timate of one standard error and an ap-proximate 95 percent confidence inter-val; and (3) Describe how estimates were

24、 cal-culated and how variances were cal-culated. APPENDIX A TO PART 1340SAMPLE DESIGN Following is a description of a sample de-sign that meets the final survey guidelines and, based upon NHTSAs experience in de-veloping and reviewing such designs, is pre-sented as a reasonably accurate and prac-tic

25、al design. Depending on the data available in a State, substitutions in this design can be made without loss of accuracy. This infor-mation is intended only as an example of a complying survey design and to provide guid-ance for States concerning recommended de-sign options. These are not design req

26、uire-ments. It is recommended that State surveys of safety belt use be designed by qualified survey statisticians. I. SAMPLE DESIGN A. Sample population: It is recommended that all controlled intersections or all road-way segments in the State (or in the parts of the State that have not been exclude

27、d by the 85 present demographic guideline) be eligible for sampling. B. First Stage: Usually, counties are the best candidates for primary sampling units (PSUs). In large States with differing geo-graphic areas, it is recommended that strati-fication of PSUs by geographic region be em-ployed prior t

28、o PSU selection. Counties should be randomly selected, preferably with VerDate Mar2010 09:39 May 11, 2011 Jkt 223076 PO 00000 Frm 00583 Fmt 8010 Sfmt 8002 Y:SGML223076.XXX 223076wwoods2 on DSK1DXX6B1PROD with CFRProvided by IHSNot for ResaleNo reproduction or networking permitted without license fro

29、m IHS-,-,-574 23 CFR Ch. III (4111 Edition) Pt. 1340, App. A probabilities proportional to vehicle miles of travel (VMT) in each county. If VMT is not available by county, PSUs can also be se-lected with probability proportional to coun-ty population. When sampling PSUs, States should ensure that an

30、 adequate mix of rural and urban areas are represented. In some cases, urban/rural stratification must be em-ployed prior to PSU selection. In other cases, it may be more practical to perform urban/ rural stratification at the second sampling stage. C. Second Stage: Within sampled PSUs, it is recomm

31、ended that road segments be strati-fied by road type. For example, a two-strata design might be major roads vs. local roads, a three strata design might be high, medium and low traffic volume roads. The sample should be allocated to these strata by esti-mated annual VMT in each stratum. The sample o

32、f road segments within a stratum should be selected with probability propor-tional to average daily VMT. When enumer-ating all local roads is impractical, addi-tional stages of selection can be introduced and alternative sample probabilities can be used. For example, census tracts within counties ca

33、n be selected with probability proportional to VMT, or, if VMT is not avail-able, proportional to the square root of the population. Next, within each sampled cen-sus tract, road segments can be selected. D. Sample Size: The following tables are provided as rough guidelines for determining sample si

34、ze for estimating belt use with the required level of precision. The numbers are based on results from previous probability- based seat belt surveys. DETERMINING FIRST STAGE SAMPLE SIZE Number of counties in State Num-ber of coun-ties in sample 10 . 7 20 . 11 30 . 13 40 . 15 50 . 16 60 . 17 70 . 18

35、80 . 19 90 . 19 100120 . 20 130170 . 21 More than 180 . 22 DETERMINING SECOND STAGE SAMPLE SIZE Average number of road segments in each sampled county Num-ber of road seg-ments sam-pled in each sample county 50 . 19 60 . 20 70 . 21 80 . 21 90 . 22 100 . 23 200 . 26 300 . 27 400 . 27 500900 . 28 More

36、 than 1000 . 29 E. Example: To achieve the required level of precision, a State with 100 counties would sample 20 counties at the first stage. At the second stage, assuming an average of 100 road segments in each sampled county, a sample of 23 road segments per county would be selected. The total sa

37、mple size would be 20460 observational sites. II. DATA COLLECTION A. Exact observation sites, such as the spe-cific intersection on a road segment, should be determined prior to conducting the obser-vations. B. Direction of traffic to be observed should be determined prior to conducting the observat

38、ions. C. If traffic volume is too heavy to accu-rately record information, predetermined protocol should exist for selecting which travel lanes to observe. D. Observations should be conducted for a predetermined time period, usually one hour. Time periods should be the same at each site. E. To minim

39、ize travel time and distance required to conduct the observations, clus-tering of sampled sites can be done. Sample sites should be grouped into geographic clus-ters, with each cluster containing major and local roads. Assignment of sites and times within clusters should be random. F. Two counts sho

40、uld be recorded for all el-igible vehicles: 1. Number of front seat outboard occu-pants. 2. Number of these occupants wearing shoulder belts. III. ESTIMATION A. Observations at each site should be weighted by the sites final probability of se-lection. B. An estimate of one standard error should be c

41、alculated for the estimate of belt VerDate Mar2010 09:39 May 11, 2011 Jkt 223076 PO 00000 Frm 00584 Fmt 8010 Sfmt 8002 Y:SGML223076.XXX 223076wwoods2 on DSK1DXX6B1PROD with CFRProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-575 National Highway Traff

42、ic Safety Admin., DOT Pt. 1340, Nt. use. Using this estimate, 95 percent con-fidence intervals for the estimate of safety belt use should be calculated. EFFECTIVE DATE NOTE: At 76 FR 18056, Apr. 1, 2011, part 1340 was revised, effective May 2, 2011. For the convenience of the user, the re-vised text

43、 is set forth as follows: PART 1340UNIFORM CRITERIA FOR STATE OBSERVATIONAL SURVEYS OF SEAT BELT USE Subpart AGeneral Sec. 1340.1 Purpose. 1340.2 Applicability. 1340.3 Definitions. Subpart BSurvey Design Requirements 1340.4 In general. 1340.5 Selection of observation sites. 1340.6 Assignment of obse

44、rvation times. 1340.7 Observation procedures. 1340.8 Quality control. 1340.9 Computation of estimates. Subpart CAdministrative Requirements 1340.10 Submission and approval of seat belt survey design. 1340.11 Post-approval alterations to survey design. 1340.12 Re-selection of observation sites. 1340.

45、13 Annual reporting requirements. APPENDIX A TO PART 1340STATE SEAT BELT USE SURVEY REPORTING FORM AUTHORITY: 23 U.S.C. 402; delegation of au-thority at 49 CFR 1.50. Subpart AGeneral 1340.1 Purpose. This part establishes uniform criteria for State surveys of seat belt use conducted under 23 U.S.C. 4

46、02, procedures for NHTSA approval of survey designs, and administra-tive requirements relating to State seat belt surveys. 1340.2 Applicability. This part applies to State surveys of seat belt use, beginning in calendar year 2012 and continuing annually thereafter. 1340.3 Definitions. As used in thi

47、s part Access ramp means the segment of a road that forms a cloverleaf or limited access interchange. Cul-de-sac means the closed end of a road that forms a loop or turn-around. Non-public road means a road on which members of the general public are not al-lowed to drive motor vehicles. Nonresponse

48、rate means, for any survey variable, the percentage of unknown values recorded for that variable. Observation site means the physical loca-tion where survey data are collected. Passenger motor vehicle means a motor vehi-cle with a gross vehicle weight rating of less than 10,000 pounds, including a p

49、assenger car, pickup truck, van, minivan or sport util-ity vehicle. Service drive means the segment of a road that provides access to businesses and rest areas. Traffic circle means the segment of a road or intersection of roads forming a round-about. Unnamed road means a road, public or pri-vate, that has no name or number designa-tion and is often a farm or logging road. Vehicular trail means a road designed or in-tended primarily for use by motor vehicle