Variables

Categories

Estimated parameter (β_n)

Estimated error parameter

Exponent of the estimated parameter (eβ_n)

Statistical significance (Wald test)

Intercept

−7.249

0.525

0.003

p ≤ 0.001

AADT

≤5500 vpd

>5500 vpd

−0.605

0.000

0.134

-

0.546

1.000

p ≤ 0.001

-

Curve radius (m)

≤600

600 - 1500

>1500

1.163

0.539

0.000

0.314

0.203

-

3.200

1.716

1.000

p ≤ 0.001

p ≤ 0.01

-

Grade (%)

Negative

Positive or zero

0.470

0.000

0.428

-

1.600

1.000

p ≤ 0.05

-

Segment length (m)

≤200

200 - 1000

≥1000

0.423

0.930

0.788

0.501

0.167

0.144

1.527

1.213

2.200

p ≤ 0.001

p ≤ 0.05

p ≤ 0.01