Table 4 Estimated Demand Equation

Table 4
Estimated Demand Equation

Dependent variable: D(LTRAFFIC)
Estimation method: weighted least squares
Total system (unbalanced) observations: 990

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Variable Coefficient Std. error t-statistic P-value
D(LGDP) 0.8901 0.0409 21.7605 0.0000
D(LPGAS) –0.3367 0.0153 –22.0050 0.0000
D(LTRAFFIC(-1)) 0.3659 0.0158 23.1470 0.0000
D(LTOLL1) –0.2092 0.0177 –11.813 0.0000
D(LTOLL2) –0.3707 0.0147 –25.248 0.0000
D(LTOLL3) –0.4449 0.0225 –19.801 0.0000
D(LTOLL4) –0.8286 0.0844 –9.8179 0.0000
D(Z1) –0.0517 0.0260 –1.9919 0.0467
D(Z2) –0.0689 0.0239 –2.8782 0.0041
D(Z3) –0.0718 0.0246 –2.9179 0.0036
D(Z4) –0.0519 0.0263 –1.9745 0.0486
D(Z5) 0.1549 0.0396 3.9136 0.0001
D(Z6) 0.1690 0.0364 4.6466 0.0000
D(Z7) 0.1196 0.0583 2.0507 0.0406
D(Z8) –0.0679 0.0219 –3.1035 0.0020
D(Z9) –0.0623 0.0201 –3.1029 0.0020
D(Z10) –0.0656 0.0286 –2.2911 0.0222
D(Z11) –0.0425 0.0227 –1.8689 0.0619
D(Z12) –0.0550 0.0250 –2.2015 0.0279
D(Z13) 0.0746 0.0251 2.9698 0.0031
D(Z14) –0.0337 0.0201 –1.6798 0.0933
D(Z15) 0.0626 0.0202 3.0952 0.0020
D(Z16) –0.0360 0.0188 –1.9175 0.0555
D(Z17) 0.0498 0.0188 2.6367 0.0085
D(Z18) 0.0445 0.0192 2.3154 0.0208
D(Z19) 0.0404 0.0153 2.6397 0.0084
D(Z20) 0.0529 0.0134 3.9563 0.0001
D(Z21) 0.1698 0.0433 3.9163 0.0001
D(Z22) 0.0812 0.0163 4.9712 0.0000
D(Z23) 0.0822 0.0207 3.9686 0.0001
D(Z24) 0.1379 0.0187 7.3903 0.0000
D(Z25) –0.1366 0.0488 –2.7992 0.0052
D(Z26) 0.0864 0.0177 4.8746 0.0000
D(Z27) 0.0751 0.0175 4.2902 0.0000
D(Z28) 0.0451 0.0206 2.1897 0.0288
R2 (average for the motorway sections) 0.74      
First order autocorrelation coefficient (pooling estimation for the motorway sections) 0.019      

Note: All variables are defined in first differences (D) of the logarithm (L). GDP = gross domestic product; PGAS = gasoline price; TRAFFIC = average daily traffic volume; TOLL1 = low toll elasticity group; TOLL2 = low-medium toll elasticity group, TOLL3 = medium-high toll elasticity group; TOLL4 = high toll elasticity group; D(Z1) to D(Z28) = first differences of the dummy variables to account for changes in the road network.