Estimating Truck Travel Time to Passenger Car or Traffic Stream Travel Time Ratio in North Carolina, USA

Figures & data

Figure 1. Example links – ramp to the next ramp or major intersection to the next major intersection.

Figure 2. Selected links in Mecklenburg County and Iredell County.

Table 1. Data Samples for GEE Modeling by Reference Speed, DOW, and TOD

DOW	≤ 30 mph	> 30 & ≤ 40 mph	> 40 & ≤ 50 mph	> 50 mph	Total
	Weekday
Morning peak period	74	104	112	671	961
Afternoon period	283	110	118	571	1,082
Evening peak period	140	83	83	689	995
Night-time period	124	90	84	478	776
	Weekend
Morning peak period	68	115	93	697	973
Afternoon period	229	129	96	657	1,111
Evening peak period	175	100	84	668	1,027
Night-time period	143	66	80	431	720
Total	1,236	797	750	4,862	7,645

Table 2. Pearson Correlation Coefficient Matrix

Variable	ID	1	2	3	4	5	6	7	8	9	10	11	12	13	14
Data density A	1	1.00
Data density B	2	−0.92	1.00
Data density C	3	−0.26	−0.11	1.00
Morning peak period	4	0.00	0.04	−0.05	1.00
Afternoon period	5	−0.12	0.06	0.17	−0.36	1.00
Evening peak period	6	0.00	0.03	−0.04	−0.34	−0.38	1.00
Night-time period	7	0.18	−0.14	−0.09	−0.28	−0.31	−0.29	1.00
Weekday	8	−0.03	0.02	0.03	0.00	0.00	0.00	0.02	1.00
Weekend	9	0.03	−0.02	−0.02	0.00	0.00	0.00	0.00	−1.00	1.00
Area type	10	0.09	−0.13	0.11	−0.06	0.04	0.00	0.04	0.00	0.00	1.00
≤ 30 mph	11	0.25	−0.23	−0.05	−0.13	0.12	0.00	0.02	0.00	0.00	0.26	1.00
> 30 & ≤ 40 mph	12	0.16	−0.15	−0.03	0.01	0.01	−0.02	0.00	0.00	0.00	0.20	−0.15	1.00
> 40 & ≤ 50 mph	13	0.08	−0.07	0.00	0.01	0.00	−0.03	0.01	0.02	0.00	0.12	−0.14	−0.11	1.00
> 50 mph	14	−0.34	0.32	0.07	0.09	−0.10	0.04	−0.02	0.00	0.00	−0.40	−0.58	−0.45	−0.43	1.00

Table 3. GEE Model – The ATT of Trucks to the ATT of Passenger Cars Ratio

Variable/Parameter	Coeff.	Std. Error	P-value
Intercept	−0.024	0.0063	<0.05
Area type	0.024	0.0028	<0.05
Data density A	0.052	0.0051	<0.05
Data density B	0.022	0.0046	<0.05
Morning peak period	0.029	0.0037	<0.05
Afternoon period	0.023	0.0037	<0.05
Evening peak period	0.043	0.0042	<0.05
Weekday	−0.007	0.0028	<0.05
≤ 30 mph	0.074	0.0055	<0.05
> 30 & ≤ 40 mph	0.046	0.0059	<0.05
> 40 mph & ≤ 50 mph	0.016	0.0048	<0.05
QIC	82.191
QICC	75.239
RMSE	0.11
MAPE	6%

Table 4. GEE Model – The ATT of Trucks to the ATT of Traffic Stream Ratio

Variable/Parameter	Coeff.	Std. Error	P-value
Intercept	−0.057	0.005	<0.05
Data density A	0.054	0.004	<0.05
Data density B	0.019	0.003	<0.05
Morning peak period	0.039	0.003	<0.05
Afternoon period	0.027	0.003	<0.05
Evening peak period	0.046	0.004	<0.05
≤ 30 mph	0.080	0.005	<0.05
> 30 & ≤ 40 mph	0.054	0.006	<0.05
> 40 mph & ≤ 50 mph	0.015	0.005	<0.05
QIC	73.187
QICC	69.702
RMSE	0.11
MAPE	6%