Bicyclist Facility Preferences and Effects on Increasing Bicycle Trips (2020)

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134 Common practice in early model development is to start with a simple linear regression model and gradually increase the complexity. Although the dependent variables of perceived safety, com- fort, and willingness to try are ordinal Likert-type variables, as mentioned in the report, linear regression has been found in the literature to be reasonably robust for five levels of ordinal values. An ordered logistic regression model was also estimated for each dependent variable and is presented in Table E.1. This type of model relaxes the assumption of linear regression that a difference of one unit in the dependent variable always means the same thing (e.g., that the difference between a 3 and a 4 is the same as the difference between a 2 and a 3). Otherwise, the model is conceptually similar to the linear regression model. All variables maintain their gen- eral significance level between the two models, and the coefficients have the same comparative relationship with each other. Although ordered logistic regression does not require constant interval differences to be maintained, it does impose the restrictive requirement that the impact of a given explanatory variable does not differ by level of the dependent variable (i.e., that the slope coefficients are constant across levels). This is called the parallel lines assumption, and its validity is tested using the Brant parallel lines test. This test was conducted on the three ordered logistic models, and the results are presented in Table E.2. A low P-value in this test for either the combined model or for a particular variable indicates violation of the parallel lines assumption. That many of the P-values obtained are below 0.05 shows that the bicycle infrastructure variables violate this assumption, indicating that a generalized ordered logit or multinomial logit model may techni- cally be more appropriate than the ordered logit, but these more advanced models come at the cost of interpretability and lack of parsimony. Alternatives to Regression A P P E N D I X E

Table E.1. Ordered logistic regression for expressed comfort, safety, and willingness to try by infrastructure characteristics. Variable Comfort Safety Willingness to Try Coefficient P Coefficient P Coefficient P Intercept Completely disagree | Disagree -1.82 *** <0.001 -1.37 *** <0.001 -1.08 *** <0.001 Intercept Disagree | Neutral -0.54 *** <0.001 -0.01 0.844 -0.32 *** <0.001 Intercept Neutral | Agree 0.71 *** <0.001 1.12 *** <0.001 0.51 *** <0.001 Intercept Agree | Completely Agree 2.49 *** <0.001 2.94 *** <0.001 1.93 *** <0.001 Bicycle Infrastructure Types Bike Lane (BL) 0.59 *** <0.001 0.72 *** <0.001 0.38 *** <0.001 Buffered BL (BB) 1.18 *** <0.001 1.41 *** <0.001 0.74 *** <0.001 One-way Protected 2.29 *** <0.001 2.82 *** <0.001 1.56 *** <0.001 Two-way Protected 2.01 *** <0.001 2.44 *** <0.001 1.30 *** <0.001 Multi-use 2.21 *** <0.001 2.63 *** <0.001 1.61 *** <0.001 Roadway Characteristics Parking -0.43 *** <0.001 -0.40 *** <0.001 -0.23 *** <0.001 Four Lanes 0.03 0.554 0.09 0.071 -0.04 0.412 Framing Effects BL—No Parking 0.67 *** <0.001 0.75 *** <0.001 0.55 *** <0.001 BBL—No Parking 0.36 *** <0.001 0.54 *** <0.001 0.30 ** 0.002 BL—Two Lanes 0.45 *** <0.001 0.56 *** <0.001 0.28 * 0.019 # of Responses 6,743 6,723 6,664 .P < 0.1, *P < 0.05, **P < 0.01, ***P < 0.001 Table E.2. Brant parallel line test results for ordered logistic regression models for comfort, safety, and willingness to try. Variable Comfort Safety Willingness to Try χ2 df P χ2 df P χ2 df P Combined Model 95.6 30 <0.01 108.9 30 <0.01 99.7 30 <0.01 Bicycle Infrastructure Types Bike Lane (BL) 8.6 3 0.04 12.3 3 0.01 10.6 3 0.01 Buffered BL (BB) 12.6 3 0.01 14.6 3 <0.01 7.2 3 0.06 One-way Protected 8.8 3 0.03 5.2 3 0.16 7.1 3 0.07 Two-way Protected 17.6 3 <0.01 41.0 3 <0.01 22.9 3 <0.01 Multi-use 15.7 3 <0.01 23.7 3 <0.01 7.8 3 0.05 Roadway Characteristics Parking 15.4 3 <0.01 11.5 3 0.01 6.6 3 0.09 Four Lanes 1.0 3 0.80 1.4 3 0.70 17.3 3 <0.01 Framing Effects BL—No Parking 1.8 3 0.62 2.3 3 0.52 5.8 3 0.12 BBL—No Parking 2.1 3 0.55 2.4 3 0.50 0.0 3 0.99 BL—Two Lanes 2.8 3 0.43 4.6 3 0.20 2.8 3 0.43

Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing America’s Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TDC Transit Development Corporation TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S. DOT United States Department of Transportation

TRA N SPO RTATIO N RESEA RCH BO A RD 500 Fifth Street, N W W ashington, D C 20001 A D D RESS SERV ICE REQ U ESTED N O N -PR O FIT O R G . U .S. PO STA G E PA ID C O LU M B IA , M D PER M IT N O . 88 Bicyclist Facility Preferences and Effects on Increasing Bicycle Trips N CH RP Research Report 941 TRB ISBN 978-0-309-48127-4 9 7 8 0 3 0 9 4 8 1 2 7 4 9 0 0 0 0