A GPS data-based analysis of built environment influences on bicyclist route preferences

ABSTRACT

This study examines the effects of built environment features, including factors of land use and road network, on bicyclists' route preferences using the data from the city of Seattle. The bicycle routes are identified using a GPS dataset collected from a smartphone application named “CycleTracks.” The route choice set is generated using the labeling route approach, and the cost functions of route alternatives are based on principal component analyses. Then, two mixed logit models, focusing on random parameters and alternative-specific coefficients, respectively, are estimated to examine bicyclists' route choice. The major findings of this study are as follows: (1) the bicycle route choice involves the joint consideration of convenience, safety, and leisure; (2) most bicyclists prefer to cycle on shorter, flat, and well-planned bicycle facilities with slow road traffic; (3) some bicyclists prefer routes surrounded by mixed land use; (4) some bicyclists favor routes which are planted with street trees or installed with street lights; and (5) some bicyclists prefer routes along with city features. This analysis provides valuable insights into how well-planned land use and road network can facilitate efficient, safe, and enjoyable bicycling.

KEYWORDS:

• Bicycle route choice
• built environment
• labeling routes
• mixed logit model
• principal component analysis
• smartphone GPS data

Acknowledgments

The authors acknowledge the help on data cleaning from Alon Bassok, Phil Hurvitz, and Peter Schmiedeskamp, the critical comments on statistical modeling suggested by Cynthia Chen and Anne Moudon, and the data support from Seattle Department of Transportation, Puget Sound Regional Council, and King County.

Notes

¹ The built environment refers to man-made urban settings that host human activities. It can be measured at a wide range of scales, from a single building to a whole city.

² The bicycle facility type is commonly classified as cycle track, bike lane, and bike boulevard. More detailed descriptions about bike facilities are stated in WSDOT's instruction (WSDOT, 2012. WSDOT road design manual: bicycle facilities chapter 1520). The order of bicyclists' preference is cycle track, bike lane, bike boulevard, and arterial route.

³ The K-shortest path routing algorithm is a generalization of the shortest path problem. “Path” is a similar term as “route.”

⁴ The labeling route approach minimizes costs by creating functions through a linear combination of factors, and labels a route with the prominent factor.

⁵ A road segment is defined by the link between two consecutive nodes.

⁶ The link elimination approach is described as continually eliminating the shortest path segments from the road network to find the next best route until converged.

⁷ The link penalty approach is labeled as repeatedly increasing the impedances of the shortest path segments to search the next best route until converged.

⁸ Trace: a trace is a type of visible mark left by a passenger, such as a footprint. The difference between a trace and a route lies in whether the footprints have been snapped to the road network or not.

⁹ Correlation here refers to the degree of independence of each alternative route. If two routes have overlapped road segments, they are correlated.

¹⁰ Path size is a spatial index that describes the portion of a route overlapping with other route alternatives.

¹¹ The transportation cost refers to the sum of input that a passenger pays to reach a destination, such as monetary cost, time cost, and physical effort cost. A cost function is a curve expressing the sum of input.

¹² The urban canyon effect could be described as smartphone signals being blocked in places where the streets are flanked by buildings.

¹³ A rounding tour is defined as a trip starting and ending at a same location or geographically approximating locations.

¹⁴ A cycle track is a type of separated route dedicated to bicycling and walking. A cycle track is commonly placed next to a major street, but separated by a curb, a hedge, or other physical barriers.

¹⁵ A bike lane is an element of the paved arterial route marked with painted lines. Bike lanes are designated exclusively for cyclists, but parallel with drive lane and street parking. In Washington State, the bike lanes are of three types, including protected bike lanes, buffered bike lanes, and conventional bike lanes.

¹⁶ A bike boulevard is signed as being a bike route in low-volume local streets, and may have traffic circles or speed bumps at intersections. Bicyclists use the same lanes with motorists when bicycling in the bike boulevard.

¹⁷ Standardization is to rescale the factors into a range of 0–1 bywhere X′ is the standardized value, X is the reported value, min(X) is the minimum X, and range (X) is the difference between the maximum X and minimum X.

¹⁸ The traffic circle contains raised concrete circles centered at local street intersections, and is designed to calm down vehicles as they enter a neighborhood.

¹⁹ FAR, short for floor area ratio, is calculated by the total area of a building divided by the area of the lot.

²³ LUM, short for land use mixture, reflects the level of integration within a given area of different types of land uses, which may include residential, office, commercial, water and parks, and public space. Land use mixture is measured by an entropy index and expressed as follows: where n is the number of different land use types, and P_i is the proportion of land in type i. The resulting variable land use mixture is an entropy index, which varies from 0 (homogeneous land use) to 1 (most mixed) land use.

²⁰ These analyses produce similar weights in the eight three-variable principal component analyses, of 53%, of 33%, and of 14%, in the three principal components. Any of the first two principal components in the eight principal component analyses explains 86% of the variances.

Additional information

Funding

The authors acknowledge funding from the Pacific Northwest Transportation Consortium (PacTrans).