Table 4-22 is a summary of the p-values corresponding to various categories of the independent variables for the four models. Only the p-values that are lower than 0.10 (indicating significance relative to the base case) are shown in the table with the values corresponding to positive coefficients highlighted in yellow. The term “NA” in the table indicates that the variable itself was excluded from the logistic regression model while “-” represents statistical insignificance between that category and the base category of the variable. Only three variables, income level, miles driven per day, and past experience with southern California toll roads were consistently significant and thus appeared in all four models.
It can be seen in Table 4-22 that the preferences of those in age group 55-64 are not significantly different from the base case (65+) in any of the three models in which the age variable appeared. It is also interesting to note that the youngest age cohort, 18-24, has the same opinion as the base case except for HOV lane to HOT lane conversion where the younger group is less likely to support the conversion. It appears that those aged 25 to 34 are the group that would, in general, consistently support the propositions.
Education level is not a significant variable in the HOV lane to HOT lane conversion model but respondents with “Some College” education are less likely to support tolls for new roads/lanes, wider distribution of toll revenues, or be open to at least private operation of toll roads. This education level might be reflecting opinions of the college students since the Inland empire region is home to two major universities, UC Riverside and CSU, San Bernardino.
Income level is one of the three variables that are significant in all the models. However, the relationship is not monotonous in nature with differences between consecutive income groups. It may be generalized that those in the middle income groups show a tendency to support the establishment of toll facilities, but have the tendency to oppose a wide distribution of toll revenues.
Home ownership is not a significant factor in any of the models except for the last one where the home owners are more likely to support wider distribution of toll revenues. Quality of personal trips is a significant factor only for the model explaining openness to private operation of toll roads.
The comparative results appear to suggest generally that those who drive less than 20 miles a day are inclined to support toll facilities. On the contrary, it is those who drive for more than 30 minutes a day who may be inclined to support toll facilities. Similarly, those who hold the view that there is at least some level of congestion are generally inclined to support toll facilities. Not surprisingly those who have a positive experience with toll facilities are inclined to support their establishment. Note that experience with southern California toll roads is one of the three independent variables that are significant in all four models. This finding is consistent with other studies which have reported that past experience with toll roads is a significant determinant of
‐ ‐ ‐ Table 4-22: Relative Significance of Variables in Four Models
Open to Support Support
Support for Private Wider
Level Comparison (Base HOV to
Variable new toll Operation Distribution
Category) HOT
roads/lanes of Toll of Toll Conversion Roads Revenues Age Group 18-24 (65+) ‐ 0.0013 NA ‐ 25-34 (65+) 0.0018 0.0009 NA 0.0015 35-44 (65+) 0.0571 ‐ NA ‐ 45-54 (65+) 0.0004 ‐ NA ‐ 55-64 (65+) ‐ ‐ NA ‐
High School Diploma/GED
Education Level (College Grad. or Higher) 0.0072 NA 0.0005 <.0001 Less than High School
Diploma (College Grad. or ‐ NA ‐ <.0001
Higher)
Some College (College Grad.
0.0032 NA 0.0002 0.0048 or Higher) Income Group $25,000-49,999 ($100,000+) ‐ 0.0018 ‐ 0.0069 $50,000-74,999 ($100,000+) ‐ 0.0197 0.0022 0.0001 $75,000-99,999 ($100,000+) 0.0041 0.0036 0.0136 0.0017 Less than $25,000 0.0012 ‐ <.0001 0.0002 ($100,000+)
Auto Availability Most of the time (Always) NA 0.0392 <.0001 NA
Occasionally (Always) NA 0.0002 <.0001 NA
Own (Rent) NA NA NA 0.0205
Miles Driven Per ≤ 10 miles 0.0002 0.0105 ‐ ‐
Day (>50 miles)
10 miles < Distance ≤ 20 miles
‐ <.0001 <.0001 0.0018
(>50 miles)
20 miles < Distance ≤ 30 miles 0.036 ‐ 0.003 ‐
(>50 miles)
30 miles < Distance ≤ 40 miles (>50 miles)
40 miles < Distance ≤ 50 miles ‐ ‐ ‐ 0.0034
(>50 miles) Hours Driven Per < 30 minutes
‐ 0.0009 0.0325 NA
Day (>2 hours)
30 minutes ≤Duration < 1 hour 0.0513 ‐ ‐
NA (>2 hours)
1 hour ≤Duration < 90 minutes
0.0001 0.0032 <.0001 NA
(>2 hours) 90 minutes ≤Duration < 2
hours (>2 hours) 0.0549 0.0138 <.0001 NA Proportion of
Congested 30-50% (Less than 30%) 0.0585 NA <.0001 0.0274
Open to Support Support
Support for Private Wider
Level Comparison (Base HOV to
Variable new toll Operation Distribution
Category) HOT
roads/lanes of Toll of Toll Conversion
Roads Revenues
NA
51-75% (Less than 30%) 0.0138 0.0127 ‐
More than 75% (Less than NA
0.0025 0.0002 ‐
30%)
Satisfactory (very NA
NA ‐ NA
unsatisfactory)
Slightly satisfactory (very NA NA
0.001 NA
unsatisfactory)
Slightly unsatisfactory (very NA NA
NA 0.0174 unsatisfactory) Unsatisfactory (very NA NA ‐ NA unsatisfactory)
Very satisfactory (very NA NA
NA ‐
unsatisfactory) General View of Mild Congestion (Severe
‐ 0.0046 0.0057
0.001 <.0001 Congestion Congestion)
Moderate Congestion (Severe 0.0476 <.0001 Congestion)
No Congestion (Severe
0.0207 <.0001 Congestion)
Truck Traffic a Yes (No)
0.0458 NA <.0001
Problem?
Transportation Too little (Just Right)
NA NA 0.0002 0.0003
Spending
Too much (Just Right) NA NA ‐ 0.0007
Government
Less than I prefer
Role in the (Just Right) 0.0405 NA NA NA
Economy
More than I prefer
‐ NA NA (Just Right) Paid Toll Yes (No) 0.0099 0.0002 0.0047 Electronically Experience with
So. Cal. Toll Mixed (None) ‐ ‐ 0.0121 0.0243
Roads Negative (None) 0.0738 0.0003 0.0108 <.0001 Positive (None) 0.0001 0.0003 ‐ 0.0034 Camera 0.016 Yes (No) 0.0042 NA NA Enforcement
Notes: “NA” indicates that the variable was excluded from the logistic regression model NA
“-” indicates statistical insignificance between that category and the base category of the variable
It is interesting that those who find the camera enforcement of tolls to be reasonable are more likely to support toll roads while they are less likely to support a wider distribution of revenues. These respondents are likely regular users of the toll roads who want the tolls to be enforced and
would like to see the toll revenues go for improvement of the same toll roads. Respondents’ attitudes about government role in the economy are significant only in the first model and the variable is not significant in any of the other models.