published journal article

Bicycles and Micromobility for Disaster Response and Recovery

Publication Date

May 1, 2023

Author(s)

Chen Chen, Dillon Fitch-Polse, Stephen Wong

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience Public Transit, Shared Mobility, & Active Transportation

Abstract

Bicycles and other forms of micromobility have been anecdotally used in past disasters to help save lives and improve community recovery. However, research and practice are scarce on this resilient transportation strategy, which limits its usefulness and possible benefits. To fill this gap, our paper investigates the potential role of bicycles and micromobility in facilitating (or limiting) disaster response and recovery. Given the lack of exploration on the topic, the research team convened an online workshop where we conducted brainstorming and focus group discussions with disaster experts from various government agencies, not-for-profit organizations, academia, and policy groups. The team presents a synthesis of that discussion, along with a review of the existing literature. The paper concludes there is strong potential for bicycles and micromobility for different disaster phases, hazard types, and groups of people. However, multiple barriers exist related to implementation and safety, suggesting a need for future research and policy in the transportation and emergency management fields and practices.

published journal article

Planning for Electric Vehicle Needs by Coupling Charging Profiles with Urban Mobility

Areas of Expertise

Safety, Public Health, & Mobility Justice Zero-Emission Vehicles & Low-Carbon Fuels

Abstract

The rising adoption of plug-in electric vehicles (PEVs) leads to the alignment of their electricity and their mobility demands. Therefore, transportation and power infrastructures are becoming increasingly interdependent. In this work, weuncoverpatternsofPEVmobilitybyintegratingforthefirsttimetwo unique data sets: (i) mobile phone activity of 1.39 million Bay Area residents and (ii) charging activity of PEVs in 580,000 sessions obtained in the same region. We present a method to estimate the individual mobility of PEV drivers at fine temporal and spatial resolution integrating survey data with mobile phone data and income information obtained from the census. Thereupon, we recommend changes in PEV charging times of commuters at their work stations that take into account individual travel needs and shave the pronounced peak in power demand. Informed by the tariff of electricity, we calculate the monetary gains to incentivize the adoption of the recommendations. These results open avenues for planning for the future of coupled transportation and electricity needs using personalized data.

technical brief

Best Practice for Pavement: Unpaving to Create Affordable, Safe, Smooth Gravel Roads

Publication Date

March 1, 2017

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience

Abstract

Many rural county road networks were created at a time when funding was greater and rural populations were often larger than they are today. Eventually, surface treatments such as chip seals or thin asphalt were applied to many of these gravel roads to provide them with an allweather surface. These treated surfaces were also desirable because conventional gravel roads are dusty, often develop washboarding quickly, and have high rates of gravel loss—which result in unsafe and uncomfortable conditions and greater damage to vehicles and crops.

technical brief

Best Practice for Pavement: Writing Concrete Specs for Durability and Sustainability

Publication Date

March 1, 2017

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience

Abstract

Concrete mixes for all applications chiefly rely on Portland cement (ASTM C150) to give them strength and durability. For this reason, specifications in traditional concrete mix designs were written to ensure that they used enough cement to meet strength and durability requirements, and often included minimum cement content requirements to be sure the buyer got their money’s worth.Unfortunately, research and practice have shown that this approach can worsen performance and carry the greatest environmental impacts—while still costing more money. 

technical brief

Best Practice for Pavement: Writing and Enforcing Specs for Asphalt Compaction

Publication Date

March 1, 2017

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience

Abstract

Most local agencies have asphalt compaction specifications in their contracts as well as inspectors who check the contractors’ operations. But following specifications that tell a contractor how to do the compaction, called method specifications, typically leads to very poor results because even the most experienced inspector or contractor cannot tell how well or poorly compacted the asphalt is by just watching the compacting operation or looking at the completed surface. In these situations the possible life can be cut in half. On the other hand, a city or county can use quantitative quality control/quality assurance (QC/QA) specifications that call for measurement of compaction to determine the extent to which the contractor has met the compaction requirements.

research report

Policies to Improve Transportation Sustainability, Accessibility, and Housing Affordability in the State of California

Publication Date

December 1, 2023

Author(s)

Daniel G. Chatman, Michael Manville, Elisa Barbour, Tamara Kerzhner, Carolina Reid

Areas of Expertise

Travel Behavior, Land Use, & the Built Environment

Abstract

This report presents an analytical review of empirical research on the interactions between housing availability and production, travel behavior, accessibility, land use policies, and transportation policies. It identifies lessons from this review for California state legislative efforts to improve housing and transportation linkages, and to increase both transportation sustainability and housing affordability. Relevant California state efforts include legislation to influence parking standards; to require up-zoning near transit stations; to influence regional housing and transportation planning goals; and to change environmental review to focus on reducing vehicle miles traveled instead of accommodating road traffic.

published journal article

Regulating TNCs: Should Uber and Lyft set their own rules?

Areas of Expertise

Infrastructure Delivery, Operations, & Resilience Public Transit, Shared Mobility, & Active Transportation Safety, Public Health, & Mobility Justice

Abstract

We evaluate the impact of three proposed regulations of transportation network companies (TNCs) like Uber, Lyft and Didi: (1) A minimum wage for drivers, (2) a cap on the number of drivers or vehicles, and (3) a per-trip congestion tax. The impact is assessed using a queuing theoretic equilibrium model which incorporates the stochastic dynamics of the app-based ride-hailing matching platform, the ride prices and driver wages established by the platform, and the incentives of passengers and drivers. We show that a floor placed under driver earnings can push the ride-hailing platform to hire more drivers and offer more rides, at the same time that passengers enjoy faster rides and lower total cost, while platform rents are reduced. Contrary to standard competitive labor market theory, enforcing a minimum wage for drivers benefits both drivers and passengers, and promotes the efficiency of the entire system. This surprising outcome holds for almost all model parameters, and it occurs because the wage floor curbs TNC labor market power. In contrast to a wage floor, imposing a cap on the number of vehicles hurts drivers, because the platform reaps all the benefits of limiting supply. The congestion tax has the expected impact: fares increase, wages and platform revenue decrease. We also construct variants of the model to briefly discuss platform subsidy, platform competition, and autonomous vehicles.

research report

A Futures Market for Demand Responsive Travel Pricing

Areas of Expertise

Transportation Economics, Funding, & Finance

Abstract

Dynamic toll pricing based on demand can increase transportation revenue while also incentivizing travelers to avoid peak traffic periods. However, given the unpredictable nature of traffic, travelers lack the information necessary to accurately predict congestion, so dynamic pricing has minimal effect on demand. Dynamic toll pricing also poses equity concerns for those who lack other travel options. This research explores a potential remedy to these concerns by using a simple “futures market” pricing mechanism in which travelers can lock in a toll price for expected trips by prepaying for future tolls, with the future price increasing as more travelers book an overlapping time slot. This approach encourages travelers to avoid driving during the peak periods when pricing increases toward capacity or to purchase trips in advance when the price remains low or discounted, thus using infrastructure capacity more efficiently. Travelers that do not prepurchase their trip are subject to the real-time market price, which is determined by dynamic congestion pricing. This futures-market mechanism can augment existing toll collection technologies and provide travelers with sufficient pricing information and purchasing options to preplan their travel and avoid excessive prices.

policy brief

Toll Pricing “Futures” Market Could Reduce Congestion and Increase Revenue

Areas of Expertise

Transportation Economics, Funding, & Finance

Abstract

Transportation agencies are increasingly relying on tolls to raise revenue and to mitigate congestion, but conventional fixed tolls do not necessarily encourage offpeak use of infrastructure, and high tolls can dampen economic productivity. Dynamically adjusting pricing based on demand can incentivize travelers to avoid peak traffic periods and shift it to other modes, but given the unpredictable nature of traffic, travelers lack the information necessary to accurately predict congestion, so dynamic pricing has minimal effect on demand. Dynamic toll pricing also poses equity concerns for those who lack other travel options, such as access to transit. A simple “futures market” pricing mechanism has the potential to address these concerns—travelers can lock in a price for expected trips by prepaying for future tolls, with the future price increasing as more travelers book an overlapping time slot. To evaluate the effectiveness of a futures market to impact travel demand, trip density, traffic flow, and revenue, this research conducted a sensitivity analysis of elasticity and pricing constraints.

published journal article

Examining the Effects of the Sacramento Dockless E-Bike Share on Bicycling and Driving

Publication Date

January 3, 2021

Areas of Expertise

Public Transit, Shared Mobility, & Active Transportation Travel Behavior, Land Use, & the Built Environment

Abstract

One way cities are looking to promote bicycling is by providing publicly or privately operated bike-share services, which enable individuals to rent bicycles for one-way trips. Although many studies have examined the use of bike-share services, little is known about how these services influence individual-level travel behavior more generally. In this study, we examine the behavior of users and non-users of a dockless, electric-assisted bike-share service in the Sacramento region of California. This service, operated by Jump until suspended due to the coronavirus pandemic, was one of the largest of its kind in the U.S., and spanned three California cities: Sacramento, West Sacramento, and Davis. We combine data from a repeat cross-sectional before-and-after survey of residents and a longitudinal panel survey of bike-share users with the goal of examining how the service influenced individual-level bicycling and driving. Results from multilevel regression models suggest that the effect of bike-share on average bicycling and driving at the population level is likely small. However, our results indicate that people who have used-bike share are likely to have increased their bicycling because of bike-share.