A bifurcation of the peak: New patterns of traffic peaking during the COVID-19 era

Recently published:

  • Gao, Yang and Levinson, D. (2022) A bifurcation of the peak: New patterns of traffic peaking during the COVID-19 era. Transportation. [doi]

This paper analyzes the emergence of two well-defined peaks during the morning peak period in the traffic flow diurnal curve. It selects six California cities as research targets, and uses California employment and household travel survey data to explain how and why this phenomenon has risen during the pandemic. The final result explains that the double-humped phenomenon results from the change in the composition of commuters during the morning peak period after the outbreak.

Traffic flow diurnal curve of Los Angeles in 2020
Traffic flow diurnal curve of Los Angeles in 2020

Prioritizing Active Transport Network Investment using Locational Accessibility

Recently published:

  • Lahoorpoor, B., Rayaprolu, H., Wu, H., and Levinson, D. (2022) Prioritizing Active Transport Network Investment using Locational Accessibility. TeMA – Journal of Land Use, Mobility and Environment. 15(2), 179-192. [doi]

This research explores prioritizing network investment to improve walking and biking access in a suburban area with a poorly connected street network. This study’s methods provide a systematic approach to design and prioritize the potential links to improve active travel in the suburban environment. An access-oriented ranking system is proposed to prioritize the contribution of links in two evaluation processes for different travel time thresholds. One of the developing suburbs in Sydney is selected as the case study, and a list of potential links is identified. Results indicate that links with the highest added access per unit of cost are the links that have the highest impact if all links are built. However, the locational network structure surrounding the point of interest may affect the order. For a radial network, closer links lead to higher access, while for a tree-like network structure, connecting branches improve access significantly. Also, farther potential links are significantly dependent on the closer links in increasing accessibility for a specific location. This suggests that in order to utilize the network, there should be a sequence in constructing the potential links. The application of access-oriented network investment is also discussed.

Miller Central Access

Equilibrium or Imbalance? Rail Transit and Land Use Mix in Station Areas

Recently published:

  • Wang, Yuning, Lu, D, and Levinson, D. (2022) Equilibrium or Imbalance? Rail Transit and Land Use Mix in Station Areas. Transportation. [doi]


Although it is widely reported that rail transit has the potential to encourage higher density development, it remains unclear whether rail transit leads to more mixed urban development across station areas. This article provides rare quantitative analysis of changes in land use mix around the rail transit system in Tianjin, China through an investigation into the spatial effects of a rail transit line which cuts across both highly developed and lessdeveloped areas. By using longitudinal data over a twelve-year period (2004–2016) and by comparing the entropy-based land-use mix index, the study shows that with the operation of rail transit, land use mix has increased in formerly low-mixed station catchments, but the change is not obvious for already highly diverse areas. It also shows that a more balanced development occurs in station areas with higher land use dominance, while the leading functions are intensified in station areas with lower land use dominance. By presenting a clear picture of the spatial distribution and patterns of land use mix changes over time, this article concludes that rail transit leads to more balanced development across different station areas in the context of China’s rapid urbanization. The outcome provides a base for further exploring how the planning of rail transit stations may help tackle the differentiated development in cities.

Keywords Rail transit · Land use mix · Spatial variations · Tianjin

Fig. 3 The land use of M1 in 2016
Fig. 3 The land use of M1 in 2016

The Spatio-temporal Evolution of Sydney’s Tram Network Using Network Econometrics

Recently published:

  • Wang, Yingshuo, Lahoorpoor, B. and Levinson, D. (2022) The Spatio-temporal Evolution of Sydney’s Tram Network Using Network Econometrics. Geographical Analysis. [doi]

This paper examines the evolution of Sydney trams using network econometrics approaches. Network econometrics extends spatial econometrics by developing weight matrices based onthe physical structure of the network, allowing for competing and complementary elementsto have distinct effects. This research establishes a digitized database of Sydney historical tramway network, providing a complete set of geo-referenced data of the opening and closing year and frequencies by time of day for every line. An autoregressive distributed lag model is specified and reveals that the combination of correlation strength and magnitude of lagged flow change on correlated links is a significant predictor of future tram service. The results indicate that complementary and competitive links play distinct roles in shaping the network structure. A link is more likely to undergo the same structural change highly complementary (upstream or downstream) links underwent previously, where the influence is measured by a combination of correlation strength and link importance, reflected by historical service levels.

Sydney land use and tram network service level in 1938.

Resilience and recovery of public transport use during COVID-19

Recently published:

  • Wang, Jiaoe, Huang, Jie, Yang, Haoran, and Levinson, D. (2022) Resilience and recovery of public transport use during COVID-19. npj Urban Sustainability 2(18) [doi]

To better understand how public transport use varied during the first year of COVID-19, we define and measure travel behavior resilience. With trip records between November 2019 and September 2020 in Kunming, China, we identify people who relied on traveling by subway both before and after the first pandemic wave. We investigate whether and how travelers recover to their pre-pandemic mobility level. We find that public transport use recovered slowly, as urban mobility is a result of urban functionality, transport supply, social context, and inter-personal differences. In general, urban mobility represents a strengthened revisiting tendency during COVID-19, as individual’s trips occur within a more limited space. We confirm that travel behavior resilience differs by groups. Commuters recover travel frequency and length, while older people decrease frequency but retain activity space. The study suggests that policymakers take group heterogeneity and travel behavior resilience into account for transport management and city restoration.

Fig. 1: Study area, analytical framework, and data selection. a Location of Kunming and its subway system. b Travel behavior resilience of public transport use. cThe trip rate in Kunming subway system between January and September 2020. (The supply function curve indicates how the public transport system reopened and adapted during the COVID-19 pandemic. The resilience triangle can be calculated with the degree of mobility change, and the periods of reduction and recovery. The trip rate is calculated by the ratio of all transit trips in each week over the weekly average number of trips in November 2019, namely before the COVID-19 pandemic. As we tracked individual trip records, frequent travelers are those who accessed the subway system frequently in November 2019, and their travel frequency recovered in September 2020. The remaining travelers in November 2019 are tracked as infrequent travelers. Note that data in June and August 2020 are unavailable.).

Prediction of the Deviation between Alternative Routes and Actual Trajectories for Bicyclists

Recently published:

  • Wang, Haotian, Emily Moylan, and David M. Levinson (2022) “Prediction of the Deviation between Alternative Routes and Actual Trajectories for Bicyclists.” Findings, June. [doi].

This study estimates a panel regression model to predict bicyclist route choice. Using GPS trajectories of 600 trips from 49 participants in spring 2006 in Minneapolis, we calculate deviation, the average distance between alternative routes and actual trajectories, as the dependent variable. Trip attributes, including trip length, Vehicle Kilometres Travelled (VKT), the number of traffic lights per kilometer, and the percentage of bike trails and separated bike lane, are included as independent variables. F-tests indicate that both fixed entity and time effect panel regression models offer better fits than the intercept-only model. According to our results, routes with shorter length and higher share of bike trails tend to have less deviation in their trajectories. Traffic lights per km, VKT, and share of bike lane are not significant at the 95% confidence level in this data set.

Figure 1. Example of Commute and Non-Commute Trips

Maximizing Access in Transit Network Design

Recently published:

  • Rayaprolu, H., Wu, H., Lahoorpoor, B., and Levinson, D. (2022) Maximizing Access in Transit Network Design. Journal of Public Transportation. 24 [doi]

This study adopts an Access-Oriented Design (AOD) framework for optimizing transit network design. We present and demonstrate a method to evaluate the best combination of local and express alternative transit system designs through the novel concept of ‘iso-access lines’. Two bus network system designs were explored for a greenfield development in suburban Sydney: through-routed transit lines (T-ways) with higher speeds and more direct service, but longer access and egress times, and local routes that provide additional spatial coverage. We developed scenarios with T-ways only, local routes only, and both, and computed transit access to jobs as a cumulative-opportunities measure for each scenario. Local routes offer greater overall access, while T-ways provide greater access-per-unit-cost. The optimal combination of the two was established by generating ‘iso-access’ lines and determining access-maximizing combinations for a given cost by applying production-theory principles. For 15-min access, the optimal combinations had T-way service frequency equivalent to 0.48 times that of local routes. This ratio increased to 1.45, 2.05 and 2.63 for 30-min, 45- min and 60-min access respectively. In practice, the method can be applied to determine optimal transit combinations for any given budget and desired access level.

Fig. 4. Schematic representation of transit connections designed for the development area. T-ways connect superblock centers with rail stations on either end. Local routes originate at rail stations, loop around superblocks and terminate at the origin stations.

Ensemble Models of For-Hire Vehicle Trips

Recently published:

Wu, Hao and Levinson, David (2022) Ensemble Models of For-Hire Vehicle Trips. Frontiers in Future Transportation. 3 [DOI]

Ensemble forecasting is class of modeling approaches that combines different data sources, models of different types, with different assumptions, and/or pattern recognition methods. By comprehensively pooling information from multiple sources, analyzed with different techniques, ensemble models can be more accurate, and can better account for different sources of real-world uncertainties. The share of for-hire vehicle (FHV) trips increased rapidly in recent years. This paper applies ensemble models to predicting for-hire vehicle (FHV) trips in Chicago and New York City, showing that properly applied ensemble models can improve forecast accuracy beyond the best single model.

All ridership is local: Accessibility, competition, and stop-level determinants of daily bus boardings in Portland, Oregon

Research on accessibility, a measure of ease of reaching potential opportunities, has advanced significantly, but the adoption of these measures by public transport agencies has lagged. One explanation may be that research has been conducted at different spatial scales from the stop level typically used by agencies. To address this gap, this study examines the relationship between accessibility to jobs and average daily bus boardings at the bus-stop level of analysis in Portland, Oregon. Our models show that daily boardings could increase by 1.8% to 2.1% for every 10% increase in accessibility, measured as the number of jobs reachable in 30 min from the bus stop by public transport. This finding supports the argument that accessibility-focused service improvements have the potential to bolster stop-level ridership since network adjustments and new services like bus-rapid-transit often yield considerable increases in accessibility. At the same time, inter-stop competition reduces an individual stop’s ridership. This study conveys the benefits of planning for accessibility at a regional scale and links regional decisions back to stop-level ridership, the context most familiar to public transport agencies, in the hope that this will accelerate and extend the adoption of accessibility in practice.

Diagram illustrating the calculation of overlapping accessibility as a measure of inter-stop competition.