Pilot Test of Fatigue Management Technologies - Final Report - Federal Motor Carrier Safety Administration

This section documents further data cleaning on AP+ ® acquired data with recorded speeds of at least 30 mph. Data from Canada Study Phase 1 1 is used to illustrate the processes involved in data quality control.

Excluded drivers

The following lists the identification numbers of 7 Canadian drivers whose data were excluded from the cleaned analysis sample used for technology assessment because of insufficient data under at least one of the two experimental conditions (FEEDBACK and NO FEEDBACK).

Driver 3 (no AP+ ® data under the NO FEEDBACK condition-presumed lost

due to technical problems in recording data on truck)

Driver 9 (no AP+ ®data under the FEEDBACK condition-presumed lost

due to technical problems in recording data on truck)
Driver 14 (no data under FEEDBACK condition-dropped out of study for a personal matter; re-enrolled later as Driver 28.)
Driver 16 (insufficient data due to noncompliance to protocol)
Driver 20 (no AP+ ®data under the FEEDBACK condition-presumed lost
due to technical problems in recording data on truck)

Driver 24 (too little AP+ ® data to analyze-presumed lost due to technical

problems in recording data on truck)

Driver 27 (too little AP+ ® data to analyze-presumed lost due to technical

problems in recording data on truck)

Driver 28 (no AP+ ® data under the NO FEEDBACK condition-presumed

lost due to technical problems in recording data on truck)

This resulted in analyzable AP+ ®black box data for n = 20 Canadian drivers (i.e., 71% complete data acquisition rate relative to the n = 28 drivers empanelled). These were used in technology assessment analyses and hypothesis testing. For data acquisition procedures other than AP+, data on more drivers was often available. For example, completed post-experimental debriefing surveys (i.e., Human Factors Questionnaire, see Appendix F) were obtained on all Canadian drivers who completed both segments of the study, regardless of whether electronic data from the AP+ ®black box were available. Consequently, the sample sizes for different dependent variables within and between measurement systems can vary considerably as to the number of drivers on which data are available.

Decisions made by the research team while meeting on October 11, 2002

During a research team meeting at ATRI in Alexandria, VA in the fall of 2002, the Biostatistics-Analysis Core (directed by G. Maislin) distributed documentation of additional problematic. These were discussed in depth and strategic data handling decisions were made as described below.

Records with durations greater than 30 seconds

The AP+ ®device stored data electronically in 1 second or longer bins. Bins longer than 1 second occurred when there were no changes in parameters being stored by the AP+ ®. In the "no records excluded" Canadian study phase sample, more than 80% of AP+ ®records (82% from the NO FEEDBACK condition and 81% from the FEEDBACK condition) summarized truck and driver status over 1 second. Approximately 12% summarized truck and driver status for 2 seconds. The remaining records (approximately 6%) summarized truck and driver status for 3 or more seconds. The distributions of record duration categories by driver and feedback condition from the Canada Study Phase 1 data are summarized in Data Quality Table 2 ( Appendix C-1). Data Quality Table 3 ( Appendix C-1) repeats this summary for the sample defined as "at least 30 mph" (n = 20 Canadian drivers used for data analyses on effects of FMT feedback). Further investigation identified extraordinarily long duration records that appeared to result from the AP+ ®clock registering elapsed time while the truck was not in use. Therefore, when attention was restricted to records in which speed was at least 30 mph, these records were excluded with some few exceptions. These exceptions were investigated for data validity. Data Quality Table 4 ( Appendix C-1) for the Canada Study Phase 1 compares the total duration of records for each driver under both conditions for the "no excluded records" samples and for the sample restricted to records with speeds of at least 30 mph. The main difference in total durations of records is exclusion of records in which the truck was standing still while other records were excluded because the truck was traveling at less than 30 mph.

All AP+ records in the ³ 30 mph sample with durations longer than 20 seconds were examined. A decision was made to exclude records with durations greater than 30 seconds, because it was deemed unlikely that none of the multiple AP+ measured truck and driver parameters would have failed to change for even a second over a period of 30 seconds or longer when the truck was operating at speeds of at least 30 mph. Excluded records amounted to 9 out of 4.7 million records (i.e., only 0.0000019%). Data Quality Tables 5 and 6 ( Appendix C-1) provide driver specific distributions of record durations under the NO FEEDBACK and FEEDBACK conditions, respectively. The same procedures were applied to data acquired in the USA drivers in study phase 2 (Appendix C-2).

Lane tracking confidence < 50%

Data Quality Table 7 ( Appendix C-1) provides the SafeTRAC ®Lane Tracking (Offset) Confidence Category (0% vs. > 0 to < 100% vs. 100%) in the "no records excluded" sample. As is evident in Data Quality Table 7 (Appendix C-1), a number of drivers had lane confidence values equal to 0%, unreliable values at certain times. After discussion with AP+ ®and SafeTRAC ®representatives, lane-tracking offset values were deemed insufficiently reliable if lane tracking confidence was less than 50%. Therefore, lane tracking offsets were set to missing for all records with lane tracking confidence less than 50%. A total of 3.8% and 2.1% of records in the ³ 30 mph sample had confidence values below 50% from SafeTRAC ®. Lateral distance, a primary outcome measure, is a function of lane tracking and so this was set to missing also for these records. Data Quality Table 8 ( Appendix C-1) provides the same information for the cleaned analysis sample. Data Quality Tables 9 and 10 ( Appendix C-1) provide greater detail with regard to the distributions of Lane Tracking Confidence values. The same procedures were applied to data acquired in the USA drivers in study phase 2 (Appendix C-2).

Driver 13 SafeTRAC ® variables

Further examination of AP+ ®records for Driver 13 indicated technological failure. Therefore, all SafeTRAC ® variables were set to missing for this driver (i.e., lane track confidence, lane track offset, and lateral distance including driver's alertness, ambient light, light/dark, indicator, event category). Also, this driver was eliminated CoPilot ® (for PERCLOS) with daylight = 0 since daylight information came from SafeTRAC ®, which was deemed nonfunctional on this Driver's truck.

Vehicle offset and lateral distance

Data Quality Table 11 for the Canada Study Phase 1 ( Appendix C-1) provides summary statistics after all exclusions contained in the cleaned analysis sample for the values of the SafeTRAC ® vehicle offset indicator as recorded by the AP+ ®system (Byte 6 of SafeTRAC ®). These exclusions include the setting of values with offset confidence < 50% to missing.

According to AssistWare Technology, the makers of SafeTRAC ®, the final five values in the 0 - 255 range of the lateral offset data byte are never used, so the translated range goes from -250 to +250cm in 2-cm increments, with a data byte value of 125 corresponding to a 0-cm lateral offset. Therefore, numbers lower than 125 indicate the vehicle is left of center while numbers higher than 125 indicate the vehicle is right of center. Specifically, a value of 0 for this byte in the output message indicates a SafeTRAC ® assessment that the vehicle's current lateral offset to be -250 cm, or 2.5 meters left of lane center. A value of 1 for this byte in the output message corresponds to a lateral offset of -248 cm, etc. In order to provide a more interpretable value, lateral distance was computed from the vehicle-offset values as:

Lateral Distance = (2*Vehicle Offset-250)

Data Quality Table 12 for the Canada Study Phase 1 (Appendix C-1) provides summary statistics for the computed lateral distance values analogous to the summary in Data Quality Table 11 provided for vehicle offset. Data Quality Tables 13 and 14 ( Appendix C-1) provide details regarding the distributions of lateral distances in the NO FEEDBACK and FEEDBACK conditions, respectively. In these tables, the distributions are summarized by providing the minimum and maximum values as well as the 10 th, 20 th, 30 th, 40 th, 50 th (median), 60 th, 70 th, 80 th, and 90 th percentiles.

SafeTRAC ® Driver Alertness

"Driver alertness" is an output provided by the SafeTRAC ®based on a proprietary algorithm using lane tracking input. The output ranges from 0 to 99. When the system is not measuring "alertness," the score is equal to 100. Data Quality Table 15 for the Canada Study Phase 1 ( Appendix C-1; comparable data for the USA study phase is in the Table 15 of Appendix C-2) provides summary statistics for SafeTRAC ®alertness for each driver under both conditions using the cleaned analysis. Data Quality Tables 16 and 17 ( Appendix C-1) provide details of the distributions for each driver in the NO FEEDBACK and FEEDBACK conditions, respectively. Examination of Driver 11's NO FEEDBACK distributions of SafeTRAC ® Driver's Alertness and lateral distance (computed from vehicle offset) revealed extreme values. Therefore, this Driver's alertness and vehicle offset (and lateral distance) were set to missing under both conditions for the cleaned analysis sample. Data Quality Table 34 ( Appendix C-1) provides the distributions of SafeTRAC events for each driver under each condition.

Steering Wheel and Wheel Movements

Examination of the AP+ ®variables "steering wheel movements" and "wheel movements" suggested that these values were reversed in some Canadian trucks due to sensor reversal at installation, which was a function of truck manufacturer type. ("Steering wheel movements" were supposed to be relatively lower values compared to "wheel movements," which were relatively larger values.) Initial programming was implemented to fix wheel movement/steering wheel movement data problems assuming the problem was truck specific. Taking into account information on which truck each driver drove, the values of wheel movements and steering wheel movements were switched for Drivers 7, 9, 13, 17, 22, 22, and 28.

We expected that within truck, there would be consistency if the cause was a mechanical switching of sensors. This proved to be the case, although there remained a few instances of inconsistencies. For example, Drivers 1, 2, and 4 had values in the range expected for steering wheel movements in both channels. Driver 11 had values that appeared to flip channels going from the NO FEEDBACK and FEEDBACK condition. That is, Driver 11 had wheel movement and steering wheel movement data switched only for FEEDBACK condition. This was the only driver with a reversal in one condition only. This is impossible under the assumption that Driver 11 used the same equipment during both conditions. Thus, wheel movement data for Drivers 1, 2, 4, 6, and 11 could not be reconciled with expected values and consequently "wheel movement" and "steering wheel movement" data for these drivers were set to missing.

Data Quality Table 18 for the Canada Study Phase 1 ( Appendix C-1) provides summary statistics for AP+ ®recorded steering wheel movement for each driver under both conditions using the cleaned analysis sample. Data Quality Tables 19 and 20 ( Appendix C-1) provide details of the cleaned analysis sample steering wheel distributions for each driver in the NO FEEDBACK and FEEDBACK conditions, respectively. Data Quality Table 21 ( Appendix C-1) provides summary statistics for AP+ ®recorded wheel movement for each driver under both conditions using the cleaned analysis sample. Data Quality Tables 22 and 23 ( Appendix C-1) provide details of the cleaned analysis sample wheel distributions for each driver in the NO FEEDBACK and FEEDBACK conditions, respectively. (The comparable tables numbered for the USA study phase can be found in Appendix C-2.)

CoPilot ® measures of PERCLOS

All CoPilot ® measures of PERCLOS values recorded when the AP+ ® daylight sensor indicated the presence of daylight (value of 1) were set to missing in the cleaned analysis sample, since the infrared-based CoPilot ® was considered accurate primarily at night. Data Quality Tables 28 and 29 for the Canada Study Phase 1 ( Appendix C-1) provide the number of records in the no exclusions sample and the cleaned analysis sample, respectively, in which the daylight indicator was equal to 0 (no daylight) or 1 (daylight). In addition, Data Quality Table 24 provides a summary of the ambient light values for each driver under both conditions.

Data Quality Table 25 for the Canada Study Phase 1 ( Appendix C-1) provides summary statistics for PERCLOS values recorded during no daylight records in the cleaned analysis sample. Data Quality Tables 26 and 27 ( Appendix C-1) provide details of the cleaned analysis sample PERCLOS distributions for each driver in the NO FEEDBACK and FEEDBACK conditions, respectively. (Appendix C-2 has comparable data for the USA study phase.)

Vehicle speed, engine rotation, longitudinal and lateral acceleration

Data Quality Tables 30 to 33 for the Canada Study Phase 1 ( Appendix C-1) provide summary statistics for vehicle speed, engine rotation, longitudinal ("X") and lateral ("Y") acceleration respectively. The ranges of the longitudinal and lateral acceleration are both from -1.28g to +1.28g.

DQ Table 1: No Records Excluded Speed Categories (mph)

Driver	N	%	N	%	N	%	N	%	N	%	N	%
	No Feedback						Feedback
	=0.62		0.62-<30		>=30		=0.62		0.62-<30		>=30
1	16063	10.9%	41925	28.4%	89424	60.7%	10480	13.0%	18826	23.4%	51283	63.6%
2	18523	10.4%	29823	16.7%	130500	73.0%	8994	5.3%	27582	16.4%	131890	78.3%
3	.	.	.	.	.	.	4913	2.8%	28619	16.3%	142204	80.9%
4	3352	1.4%	51251	21.6%	182506	77.0%	4597	2.2%	43276	20.8%	160403	77.0%
5	186	0.2%	13674	17.0%	66564	82.8%	35	0.2%	2860	13.1%	18969	86.8%
6	175	0.2%	16364	20.2%	64301	79.5%	46	0.1%	5639	13.5%	35984	86.4%
7	346	0.3%	17375	13.0%	115930	86.7%	691	0.4%	29555	18.6%	128588	81.0%
8	483	0.3%	23068	16.2%	118854	83.5%	165	0.1%	12149	10.1%	107403	89.7%
9	1104	0.6%	45482	23.6%	146222	75.8%	.	.	.	.	.	.
10	696	0.2%	41023	13.1%	272512	86.7%	692	0.2%	50511	15.5%	274781	84.3%
11	69	0.3%	5676	22.1%	19926	77.6%	738	0.4%	32719	18.6%	142818	81.0%
12	43	0.2%	6304	36.1%	11105	63.6%	131	0.2%	15872	24.2%	49527	75.6%
13	1168	0.8%	44123	28.9%	107503	70.4%	780	0.5%	33376	20.8%	126580	78.8%
15	1136	0.5%	62381	25.7%	178800	73.8%	740	0.3%	44492	18.2%	199487	81.5%
17	902	0.8%	48775	43.4%	62833	55.8%	142	0.4%	8267	26.0%	23433	73.6%
18	1183	0.3%	68560	15.9%	361800	83.8%	372	0.2%	27322	13.6%	173511	86.2%
19	160	0.5%	10764	36.4%	18620	63.0%	151	0.5%	11825	40.5%	17241	59.0%
20	96	0.4%	6097	25.9%	17363	73.7%	.	.	.	.	.	.
21	714	0.3%	46550	21.2%	171890	78.4%	854	0.3%	49925	20.1%	197442	79.5%
22	1086	0.5%	46474	21.8%	166041	77.7%	1258	0.6%	51143	23.6%	164070	75.8%
23	202	0.6%	18158	54.9%	14716	44.5%	278	0.7%	20746	51.4%	19338	47.9%
24	5	3.0%	162	97.0%	.	.	.	.	1	100.0%	.	.
25	788	0.6%	28846	21.9%	102015	77.5%	1044	0.6%	36697	21.0%	136953	78.4%
26	1414	0.5%	67471	21.5%	244947	78.1%	500	0.4%	23922	21.3%	87806	78.2%
27	13	0.8%	1221	72.5%	449	26.7%	1	0.5%	219	99.5%	.	.
28	.	.	.	.	.	.	100	0.8%	7015	52.6%	6211	46.6%

Total/Mean	49907	1.4%	741547	29.8%	2664821	71.8%	37702	1.3%	582558	29.1%	2395922	75.9%

DQ Table 2: No Records Excluded Record Duration Category (seconds)

Driver	N	%	N	%	N	%	N	%	N	%	N	%
	No Feedback						Feedback
	1 sec		2 sec		>=3 sec		1 sec		2 sec		>=3 sec
1	114612	77.8%	19408	13.2%	13379	9.1%	65216	80.9%	9656	12.0%	5700	7.1%
2	139779	78.2%	24653	13.8%	14372	8.0%	105028	62.4%	31999	19.0%	31400	18.6%
3	.	.	.	.	.	.	135952	77.4%	24917	14.2%	14753	8.4%
4	194605	82.1%	29135	12.3%	13334	5.6%	165059	79.3%	27839	13.4%	15352	7.4%
5	63160	78.6%	11565	14.4%	5641	7.0%	15569	71.2%	3965	18.1%	2330	10.7%
6	69891	86.5%	8090	10.0%	2828	3.5%	34815	83.6%	4881	11.7%	1952	4.7%
7	113777	85.2%	14837	11.1%	4872	3.6%	138023	87.0%	15866	10.0%	4804	3.0%
8	119312	83.8%	16539	11.6%	6536	4.6%	98883	82.6%	15399	12.9%	5435	4.5%
9	153418	79.7%	25764	13.4%	13334	6.9%	.	.	.	.	.	.
10	257477	81.9%	40174	12.8%	16555	5.3%	273484	83.9%	37174	11.4%	15295	4.7%
11	21153	82.5%	2923	11.4%	1577	6.1%	141897	80.6%	23505	13.4%	10631	6.0%
12	13638	78.2%	2332	13.4%	1480	8.5%	48886	74.7%	9328	14.2%	7252	11.1%
13	112602	73.8%	22550	14.8%	17482	11.5%	129876	80.9%	21049	13.1%	9675	6.0%
15	196417	81.1%	30419	12.6%	15453	6.4%	196822	80.4%	31897	13.0%	15953	6.5%
17	94289	83.9%	12269	10.9%	5806	5.2%	25821	81.1%	4279	13.4%	1723	5.4%
18	360905	83.6%	51127	11.8%	19471	4.5%	171392	85.2%	22135	11.0%	7630	3.8%
19	23496	79.5%	3715	12.6%	2331	7.9%	23184	79.4%	3572	12.2%	2453	8.4%
20	16911	71.9%	3648	15.5%	2947	12.5%	.	.	.	.	.	.
21	177701	81.1%	28082	12.8%	13348	6.1%	204169	82.3%	29879	12.0%	14156	5.7%
22	167838	78.7%	29994	14.1%	15493	7.3%	182884	84.6%	23931	11.1%	9317	4.3%
23	27176	82.2%	3892	11.8%	2001	6.1%	32423	80.4%	4895	12.1%	3028	7.5%
24	154	92.8%	8	4.8%	4	2.4%	.	.	.	.	1	100.0%
25	114276	86.9%	12784	9.7%	4479	3.4%	148390	85.0%	18581	10.6%	7560	4.3%
26	276103	88.0%	28018	8.9%	9642	3.1%	99979	89.1%	9477	8.4%	2751	2.5%
27	1502	89.3%	95	5.6%	85	5.1%	196	89.5%	17	7.8%	6	2.7%
28	.	.	.	.	.	.	10611	79.7%	1604	12.0%	1105	8.3%

Total/Mean	2830192	82.0%	422021	11.8%	202450	6.2%	2448559	80.9%	375845	12.5%	190262	10.5%

DQ Table 3: Cleaned Analysis Sample Record Duration Category (seconds)

Driver	N	%	N	%	N	%	N	%	N	%	N	%
	No Feedback						Feedback
	1 sec		2 sec		>=3 sec		1 sec		2 sec		>=3 sec
1	65873	73.7%	14590	16.3%	8956	10.0%	41373	80.7%	6964	13.6%	2934	5.7%
2	101278	77.6%	19907	15.3%	9282	7.1%	75313	57.1%	28557	21.7%	27991	21.2%
4	143961	78.9%	26784	14.7%	11754	6.4%	121451	75.7%	25425	15.9%	13514	8.4%
5	50467	75.9%	10831	16.3%	5214	7.8%	12964	68.3%	3780	19.9%	2225	11.7%
6	54247	84.4%	7545	11.7%	2483	3.9%	29455	81.9%	4683	13.0%	1825	5.1%
7	96927	83.7%	14313	12.4%	4555	3.9%	109346	85.1%	14904	11.6%	4224	3.3%
8	96995	81.6%	15866	13.4%	5981	5.0%	87149	81.1%	15050	14.0%	5204	4.8%
10	218251	80.1%	38618	14.2%	15620	5.7%	225095	81.9%	35355	12.9%	14309	5.2%
11	15805	79.4%	2680	13.5%	1425	7.2%	110466	77.4%	22343	15.7%	9820	6.9%
12	7911	71.2%	1898	17.1%	1296	11.7%	34411	69.6%	8324	16.8%	6734	13.6%
13	71260	66.4%	20196	18.8%	15938	14.8%	98099	77.6%	19649	15.5%	8728	6.9%
15	136708	76.5%	28078	15.7%	13995	7.8%	154360	77.4%	30203	15.1%	14880	7.5%
17	48179	76.8%	9901	15.8%	4670	7.4%	18149	77.5%	3777	16.1%	1498	6.4%
18	294879	81.5%	48840	13.5%	18049	5.0%	145021	83.6%	21333	12.3%	7121	4.1%
19	13405	72.0%	3219	17.3%	1996	10.7%	12461	72.3%	2868	16.6%	1912	11.1%
21	133335	77.6%	26238	15.3%	12296	7.2%	156042	79.0%	28324	14.3%	13061	6.6%
22	124439	75.0%	27262	16.4%	14117	8.5%	134244	82.0%	21583	13.2%	7975	4.9%
23	10933	74.3%	2556	17.4%	1222	8.3%	14016	72.5%	3268	16.9%	2039	10.6%
25	86323	84.7%	11882	11.7%	3729	3.7%	112675	82.3%	17585	12.9%	6569	4.8%
26	210769	86.1%	26071	10.6%	8043	3.3%	76827	87.5%	8785	10.0%	2176	2.5%

Total/Mean	1981945	77.9%	357275	14.9%	160621	7.3%	1768917	77.5%	322760	14.9%	154739	7.6%

Data Quality Table 4: No Exclusions and >=30 mph Sum of Record Durations (hours)

Driver	Sum	Sum	Sum	Sum
	No Feedback		Feedback
	All Records	>=30 mph	All Records	>=30 mph
1	248.9	36.5	308.0	18.4
2	254.6	48.7	319.9	70.1
3	.	.	269.8	55.2
4	247.2	67.0	307.2	62.5
5	274.3	25.2	282.1	8.0
6	325.9	21.6	133.7	12.6
7	299.4	39.3	324.9	42.7
8	172.7	41.7	189.2	37.6
9	260.5	56.9	.	.
10	291.3	97.9	289.8	96.6
11	89.6	7.4	340.6	53.1
12	106.6	4.8	243.8	22.0
13	350.5	50.6	302.6	47.1
15	354.8	68.3	307.9	75.2
17	341.3	23.6	314.0	8.6
18	365.7	126.8	304.4	59.1
19	216.1	7.7	207.4	7.2
20	57.2	18.8	.	.
21	334.3	64.4	320.4	72.6
22	312.2	64.9	335.2	59.6
23	316.5	5.7	334.4	7.9
24	2.2	.	407.5	.
25	310.3	34.2	338.3	47.6
26	359.0	81.1	118.1	28.3
27	130.9	0.2	0.1	.
28	.	.	322.1	2.9

Mean	250.9	43.2	275.9	40.7

DQ Table 5: Cleaned Analysis Sample NF Record Duration Distributions (seconds)

Driver	N	1 sec	2 sec	3 sec	4 sec	5 sec	6-10 sec	11-15 sec	16-20 sec	21-25 sec	26-30 sec	>30 sec
	No Feedback (Number of records at each duration)
1	89393	65873	14590	4809	1971	982	1094	55	17	2	.	.
2	130453	101278	19907	5854	1958	778	655	15	4	4	.	.
4	182480	143961	26784	7279	2556	1024	854	17	4	1	.	.
5	66510	50467	10831	3348	1141	429	291	2	1	.	.	.
6	64273	54247	7545	1749	518	130	84	.	.	.	.	.
7	115791	96927	14313	3177	897	300	177	.	.	.	.	.
8	118840	96995	15866	3944	1257	438	337	2	1	.	.	.
10	272473	218251	38618	10022	3321	1263	976	16	4	2	.	.
11	19909	15805	2680	791	341	139	148	5	.	.	.	.
12	11095	7911	1898	636	286	135	200	26	2	1	.	.
13	107276	71260	20196	7565	3601	1882	2480	207	61	16	8	.
15	178751	136708	28078	8356	3123	1233	1210	40	3	.	.	.
17	62743	48179	9901	2921	1028	405	296	11	2	.	.	.
18	361754	294879	48840	12091	3745	1241	948	10	.	.	.	.
19	18614	13405	3219	1146	398	227	209	5	5	.	.	.
21	171847	133335	26238	7507	2604	1131	1000	26	5	1	.	.
22	165774	124439	27262	8301	3064	1321	1302	55	15	9	6	.
23	14710	10933	2556	752	272	108	87	1	1	.	.	.
25	101934	86323	11882	2616	727	242	143	1	.	.	.	.
26	244864	210769	26071	5455	1551	559	418	21	15	3	2	.

Total/Mean	2499484	99097	17864	4916	1718	698	645	29	9	4	5

DQ Table 6: Cleaned Analysis Sample FB Record Duration Distributions (seconds)

Driver	N	1 sec	2 sec	3 sec	4 sec	5 sec	6-10 sec	11-15 sec	16-20 sec	21-25 sec	26-30 sec	>30 sec
	Feedback (Number of records at each duration)
1	51266	41373	6964	1856	593	249	221	10	.	.	.	.
2	131697	75313	28557	13061	6618	3506	4347	231	52	12	.	.
4	160346	121451	25425	7809	2892	1373	1319	59	17	.	1	.
5	18965	12964	3780	1316	507	208	186	3	1	.	.	.
6	35963	29455	4683	1232	379	122	90	2	.	.	.	.
7	128474	109346	14904	3055	790	252	127	.	.	.	.	.
8	107401	87149	15050	3615	1049	345	192	1	.	.	.	.
10	274740	225095	35355	9141	3040	1193	900	15	1	.	.	.
11	142616	110466	22343	6195	2081	822	690	18	1	.	.	.
12	49454	34411	8324	3296	1559	808	1013	26	15	2	.	.
13	126468	98099	19649	5434	1931	757	581	15	1	1	.	.
15	199417	154360	30203	8853	3350	1389	1231	23	6	2	.	.
17	23423	18149	3777	969	333	120	74	1	.	.	.	.
18	173470	145021	21333	4841	1459	504	310	2	.	.	.	.
19	17232	12461	2868	1054	408	202	219	13	5	2	.	.
21	197408	156042	28324	8021	2789	1143	1055	30	4	.	.	.
22	163799	134244	21583	5235	1678	616	436	7	.	.	.	.
23	19322	14016	3268	1162	475	201	200	.	.	.	.	.
25	136826	112675	17585	4300	1339	556	367	4	.	.	.	.
26	87787	76827	8785	1588	407	116	64	.	.	.	.	.

Total/Mean	2246074	88446	16138	4602	1684	724	681	27	10	4	1

DQ Table 7: No Records Excluded SafeTRAC Lane Tracking (Offset) Confidence Category

Driver	N	%	N	%	N	%	N	%	N	%	N	%
	No Feedback						Feedback
	0%		>0% to <100%		100%		0%		>0% to <100%		100%
1	735	3.2%	21977	94.3%	584	2.5%	1273	11.3%	9745	86.9%	201	1.8%
2	675	2.0%	32124	93.9%	1429	4.2%	364	1.6%	21517	94.0%	1021	4.5%
3	.	.	.	.	.	.	339	1.3%	23629	93.5%	1305	5.2%
4	320	1.6%	18820	96.1%	451	2.3%	435	2.8%	14464	93.9%	498	3.2%
5	99	1.4%	6781	93.7%	357	4.9%	14	1.0%	1256	89.4%	135	9.6%
6	63	0.7%	8242	91.6%	691	7.7%	17	0.6%	2657	95.7%	101	3.6%
7	3748	26.8%	9665	69.1%	566	4.0%	85	0.6%	12501	94.6%	631	4.8%
8	83	0.8%	9635	96.4%	273	2.7%	35	0.7%	5016	96.8%	131	2.5%
9	17140	54.6%	14018	44.7%	235	0.7%	.	.	.	.	.	.
10	16787	48.0%	17401	49.7%	794	2.3%	224	1.0%	21393	93.5%	1255	5.5%
11	2164	22.0%	7574	77.1%	88	0.9%	262	2.3%	11091	95.3%	280	2.4%
12	96	5.9%	1453	90.0%	66	4.1%	198	4.2%	4338	92.5%	153	3.3%
13	150912	99.8%	325	0.2%	4	0.0%	123	1.0%	11740	96.1%	353	2.9%
15	303	1.6%	18221	96.1%	444	2.3%	239	1.4%	16464	96.1%	438	2.6%
17	228	1.5%	14440	96.0%	373	2.5%	18	0.7%	2643	97.1%	61	2.2%
18	450	1.5%	29464	95.6%	909	2.9%	2981	18.8%	12395	78.3%	456	2.9%
19	22	0.5%	4348	96.9%	118	2.6%	36	0.9%	3778	95.8%	128	3.2%
20	52	1.9%	2530	90.1%	225	8.0%	.	.	.	.	.	.
21	289	1.8%	15353	96.1%	336	2.1%	639	4.0%	15166	94.3%	285	1.8%
22	14413	45.1%	16636	52.0%	914	2.9%	258	0.9%	27344	92.8%	1874	6.4%
23	117	1.7%	6463	96.0%	149	2.2%	121	1.6%	7517	96.5%	155	2.0%
24	2	3.7%	52	96.3%	.	.	.	.	.	.	.	.
25	88	0.7%	11621	93.4%	729	5.9%	131	0.7%	16959	94.6%	834	4.7%
26	498	1.6%	29372	95.2%	977	3.2%	128	1.3%	9263	94.6%	401	4.1%
27	4	0.8%	470	94.8%	22	4.4%	220	100.0%	.	.	.	.
28	.	.	.	.	.	.	107	3.7%	2686	94.1%	61	2.1%

Total/Mean	209288	13.7%	296985	83.1%	10734	3.3%	8247	7.1%	253562	93.5%	10757	3.7%

DQ Table 8: Cleaned Analysis Sample SafeTRAC Lane Tracking (Offset) Confidence Category

Driver	N	%	N	%	N	%	N	%	N	%	N	%
	No Feedback						Feedback
	0%		>0% to <100%		100%		0%		>0% to <100%		100%
1	1	0.0%	2965	93.5%	206	6.5%	.	.	1394	93.1%	104	6.9%
2	19	0.1%	12320	91.3%	1156	8.6%	4	0.0%	8248	90.6%	854	9.4%
4	8	0.3%	2674	93.4%	180	6.3%	1	0.0%	2582	93.6%	176	6.4%
5	.	.	1909	88.6%	245	11.4%	.	.	383	85.5%	65	14.5%
6	.	.	3728	86.1%	601	13.9%	.	.	681	88.9%	85	11.1%
7	3	0.1%	3992	89.4%	470	10.5%	.	.	3956	89.6%	459	10.4%
8	1	0.0%	2242	94.1%	139	5.8%	.	.	1507	95.1%	78	4.9%
10	3	0.0%	5585	91.6%	508	8.3%	5	0.1%	6922	91.2%	661	8.7%
11	1928	27.4%	5049	71.9%	49	0.7%	6	0.2%	2382	94.7%	126	5.0%
12	.	.	246	94.3%	15	5.7%	.	.	834	91.5%	77	8.5%
13	.	.	.	.	.	.	.	.	.	.	.	.
15	4	0.1%	2736	95.4%	128	4.5%	32	0.7%	4670	94.9%	219	4.5%
17	.	.	1421	91.4%	134	8.6%	1	0.2%	447	90.9%	44	8.9%
18	15	0.2%	9240	94.0%	572	5.8%	11	0.2%	4498	93.8%	284	5.9%
19	1	0.1%	681	90.4%	71	9.4%	.	.	681	90.3%	73	9.7%
21	7	0.2%	2758	94.7%	146	5.0%	9	0.3%	3009	95.8%	123	3.9%
22	1	0.0%	5477	89.4%	645	10.5%	4	0.0%	12255	89.7%	1399	10.2%
23	2	0.3%	656	92.5%	51	7.2%	1	0.1%	876	92.4%	71	7.5%
25	3	0.1%	4513	91.7%	406	8.2%	3	0.1%	5461	91.7%	489	8.2%
26	144	1.1%	12235	93.5%	706	5.4%	8	0.2%	3893	92.8%	292	7.0%

Total/Mean	2140	2.0%	80427	90.9%	6428	7.5%	85	0.2%	64679	91.9%	5679	8.0%

DQ Table 9: Cleaned Analysis Sample NF SafeTRAC Lane Tracking (Offset) Confidence Category

Driver	N	0%	>0-10%	>10-20%	>20-30%	>30-40%	>40-50%	>50-60%	>60-70%	>70-80%	>80-90%	>90-100%
	No Feedback (Percentages in Each Category)
1	89424	1.02%	0.59%	0.26%	0.19%	0.17%	0.14%	0.16%	0.14%	0.17%	0.19%	96.98%
2	130500	2.37%	1.30%	0.49%	0.40%	0.36%	0.34%	0.36%	0.32%	0.28%	0.22%	93.55%
4	182506	1.32%	0.55%	0.21%	0.17%	0.15%	0.16%	0.17%	0.14%	0.14%	0.13%	96.85%
5	66564	0.88%	0.44%	0.17%	0.12%	0.12%	0.09%	0.14%	0.11%	0.11%	0.13%	97.69%
6	64301	0.40%	0.16%	0.07%	0.08%	0.06%	0.06%	0.06%	0.06%	0.07%	0.09%	98.90%
7	115930	3.57%	0.40%	0.18%	0.12%	0.10%	0.10%	0.12%	0.08%	0.10%	0.09%	95.15%
8	118854	1.58%	0.81%	0.26%	0.21%	0.17%	0.18%	0.18%	0.16%	0.17%	0.17%	96.13%
10	272512	5.98%	0.25%	0.14%	0.11%	0.09%	0.10%	0.12%	0.09%	0.09%	0.10%	92.94%
11	19926	11.53%	1.27%	0.65%	0.49%	0.43%	0.35%	4.52%	0.25%	0.37%	0.40%	79.76%
12	11105	0.57%	0.36%	0.26%	0.17%	0.15%	0.23%	0.22%	0.13%	0.15%	0.19%	97.58%
13	.	.	.	.	.	.	.	.	.	.	.	.
15	178800	0.89%	0.47%	0.26%	0.24%	0.20%	0.22%	0.24%	0.19%	0.16%	0.17%	96.95%
17	62833	0.68%	0.50%	0.17%	0.15%	0.10%	0.10%	0.11%	0.10%	0.08%	0.08%	97.93%
18	361800	2.32%	0.94%	0.33%	0.24%	0.21%	0.19%	0.22%	0.19%	0.17%	0.18%	95.01%
19	18620	0.89%	0.32%	0.14%	0.12%	0.15%	0.08%	0.11%	0.09%	0.06%	0.07%	97.99%
21	171890	0.45%	0.21%	0.12%	0.10%	0.10%	0.08%	0.09%	0.07%	0.05%	0.07%	98.66%
22	166040	5.26%	0.31%	0.14%	0.11%	0.09%	0.08%	0.11%	0.08%	0.09%	0.09%	93.64%
23	14716	1.38%	0.84%	0.47%	0.30%	0.27%	0.16%	0.37%	0.16%	0.20%	0.21%	95.64%
25	102015	1.14%	0.58%	0.31%	0.24%	0.19%	0.15%	0.21%	0.15%	0.12%	0.15%	96.78%
26	244947	4.33%	0.44%	0.28%	0.22%	0.17%	0.16%	0.50%	0.14%	0.12%	0.11%	93.53%

Total/Mean	2393283	2.45%	0.57%	0.26%	0.20%	0.17%	0.16%	0.42%	0.14%	0.14%	0.15%	95.35%

DQ Table 10: Cleaned Analysis Sample FB SafeTRAC Lane Tracking (Offset) Confidence Category

Driver	N	0%	>0-10%	>10-20%	>20-30%	>30-40%	>40-50%	>50-60%	>60-70%	>70-80%	>80-90%	>90-100%
	Feedback (Percentages in Each Category)
1	51283	1.49%	0.72%	0.22%	0.17%	0.13%	0.10%	0.24%	0.08%	0.13%	0.14%	96.58%
2	131890	0.71%	0.47%	0.18%	0.16%	0.14%	0.12%	0.15%	0.12%	0.10%	0.12%	97.73%
4	160402	0.76%	0.39%	0.18%	0.15%	0.12%	0.12%	0.12%	0.11%	0.11%	0.11%	97.83%
5	18969	0.33%	0.17%	0.14%	0.07%	0.08%	0.11%	0.13%	0.18%	0.21%	0.29%	98.29%
6	35984	0.24%	0.10%	0.08%	0.05%	0.03%	0.04%	0.07%	0.03%	0.04%	0.02%	99.30%
7	128588	0.93%	0.44%	0.18%	0.14%	0.17%	0.17%	0.21%	0.18%	0.14%	0.13%	97.32%
8	107403	0.33%	0.16%	0.10%	0.09%	0.06%	0.07%	0.08%	0.05%	0.05%	0.05%	98.97%
10	274781	0.39%	0.27%	0.14%	0.12%	0.10%	0.07%	0.11%	0.08%	0.09%	0.08%	98.55%
11	142818	0.92%	0.32%	0.15%	0.10%	0.10%	0.09%	0.12%	0.10%	0.10%	0.11%	97.87%
12	49527	0.44%	0.20%	0.07%	0.07%	0.05%	0.05%	0.08%	0.07%	0.04%	0.07%	98.87%
13	.	.	.	.	.	.	.	.	.	.	.	.
15	199487	1.44%	0.57%	0.20%	0.16%	0.14%	0.13%	0.21%	0.11%	0.11%	0.13%	96.81%
17	23433	0.35%	0.13%	0.05%	0.02%	0.03%	0.04%	0.09%	0.04%	0.01%	0.06%	99.20%
18	173511	3.75%	1.62%	0.36%	0.25%	0.24%	0.22%	0.28%	0.19%	0.22%	0.20%	92.67%
19	17241	1.00%	0.42%	0.17%	0.17%	0.13%	0.10%	0.10%	0.08%	0.12%	0.14%	97.57%
21	197442	0.48%	0.36%	0.24%	0.18%	0.18%	0.82%	0.16%	0.12%	0.11%	0.10%	97.25%
22	164069	1.76%	0.93%	0.41%	0.28%	0.27%	0.31%	0.45%	0.28%	0.29%	0.29%	94.73%
23	19338	0.64%	0.64%	0.42%	0.31%	0.26%	0.25%	0.25%	0.23%	0.26%	0.21%	96.52%
25	136953	1.44%	0.59%	0.24%	0.18%	0.16%	0.17%	0.19%	0.21%	0.17%	0.17%	96.47%
26	87806	0.66%	0.49%	0.25%	0.18%	0.17%	0.15%	0.15%	0.13%	0.13%	0.13%	97.56%

Total/Mean	2120925	0.95%	0.47%	0.20%	0.15%	0.14%	0.17%	0.17%	0.12%	0.13%	0.13%	97.37%

Data Quality Table 11: Cleaned Analysis Sample SafeTRAC Vehicle Offset (unweighted by record duration)

Driver	N	Mean	Std	Med	Min	Max	N	Mean	Std	Med	Min	Max
	No Feedback						Feedback
1	87319	125.6	16.7	126.0	0.0	247.0	49834	126.6	16.1	127.0	1.0	247.0
2	123664	118.5	19.7	119.0	0.0	250.0	129556	120.2	17.4	120.0	0.0	250.0
4	177846	130.5	13.4	131.0	0.0	250.0	157669	128.8	13.2	129.0	0.0	249.0
5	65364	121.8	14.0	122.0	1.0	249.0	18798	123.9	12.8	124.0	2.0	246.0
6	63768	119.2	13.7	120.0	4.0	247.0	35789	121.8	12.5	122.0	7.0	245.0
7	110761	122.3	14.3	123.0	0.0	250.0	126005	122.3	13.6	123.0	1.0	249.0
8	115069	128.9	15.0	129.0	0.0	250.0	106549	129.6	12.9	130.0	1.0	246.0
10	254388	130.4	15.3	131.0	0.0	250.0	271790	129.9	16.2	130.0	0.0	248.0
11	0	.	.	.	.	.	0	.	.	.	.	.
12	10915	129.1	14.4	129.0	3.0	246.0	49098	126.4	12.7	127.0	2.0	246.0
13	0	.	.	.	.	.	0	.	.	.	.	.
15	174757	137.0	15.8	138.0	0.0	250.0	194255	138.5	17.8	140.0	0.0	250.0
17	61770	127.3	14.8	127.0	3.0	249.0	23291	127.6	14.4	128.0	0.0	246.0
18	346546	137.9	18.6	139.0	0.0	250.0	162376	137.2	18.5	138.0	0.0	250.0
19	18306	124.4	16.3	125.0	0.0	249.0	16897	123.7	16.5	124.0	2.0	249.0
21	170081	136.0	15.2	137.0	0.0	249.0	193010	136.7	15.6	137.0	0.0	250.0
22	156105	124.4	15.2	125.0	0.0	250.0	157614	120.1	17.7	120.0	0.0	250.0
23	14217	129.3	19.2	130.0	0.0	248.0	18852	130.5	20.7	131.0	0.0	248.0
25	99382	126.5	17.7	127.0	0.0	250.0	133168	127.2	17.5	127.0	0.0	250.0
26	231285	133.3	22.3	135.0	0.0	250.0	86148	133.5	20.8	134.0	0.0	250.0

Mean		127.9		128.5				128.0		128.4

Data Quality Table 12: Cleaned Analysis Sample Lateral Distance (2*Vehicle Offset-250) (unweighted by record duration)