Policy

Advanced Air Mobility

Cohen, Adam
Shaheen, Susan A.
2025

This entry discusses key terms, emerging infrastructure concepts, and the potential impacts of advanced air mobility (AAM). It then concludes with a discussion of potential challenges and the need for research and policy to guide sustainable and equitable outcomes.

Psychological Economics, Travel Behavior, Residential Location Choice, and Sustainability: Possible New Rationales for Policy Intervention

Chatman, Dan
Broaddus, Andrea
2011

The sustainability policy agenda includes various land use, road pricing, and parking pricing policies that are intended to reduce the use and ownership of autos in order to lower carbon emissions, pollution and road congestion. Such well-established policy interventions are largely rooted in the microeconomic concepts of market failure and externalities. But recent research in psychological economics has identified a new kind of problem: people may make decisions that are not in their own self-interest, contrary to the underlying microeconomic assumption that people are “rational actors...

How Will Smart Growth Land-use Policies Affect Travel? A Theoretical Discussion on the Importance of Residential Sorting

Cao, Xinyu
Chatman, Daniel
2016

Do policies to encourage compact, mixed use, pedestrian-friendly land-use patterns reduce driving? Not necessarily. Understanding how the built environment affects travel patterns is complex, not least because households may choose their neighborhoods on the basis of how they expect to get around. Some scholars have argued that ignoring this process of residential sorting, or ‘self-selection’, causes overestimates of built-environment influences and leads to false optimism about the efficacy of land-use policies in influencing travel. But others have suggested that residential self-...

Explaining the “Immigrant Effect” on Auto Use: The Influences of Neighborhoods and Preferences

Chatman, Daniel G.
2014

Since immigrants will account for most urban growth in the United States for the foreseeable future, better understanding their travel patterns is a critical task for transportation and land use planners. Immigrants initially travel in personal vehicles far less than the US-born, even when controlling for demographics, but their reliance on autos increases the longer they live in the US. Cultural or habitual differences, followed by assimilation to auto use, could partly explain this pattern; and it may also be partly due to changes in locations and characteristics of home and work...

Equity in Congestion-priced Parking: A Study of SFpark, 2011 to 2013

Chatman, Daniel G.
Manville, Michael
2018

Cities could reduce or eliminate cruising for parking by correctly setting parking meter rates, but would doing so harm lower-income drivers? We examined the question using data on more than 17,000 parked vehicles and their drivers from SFpark, a federally funded market-priced parking experiment in San Francisco. But we found that lower-income parkers are more likely to use street parking and meter rates had small effects on usage. Raising prices did not increase sorting across blocks by income. Controlled analysis yielded mixed and weak evidence that lower-income parkers may be less...

A Wireless Token Ring Protocol for Intelligent Transportation Systems

Lee, D.
Attias, R.
Puri, A.
Sengupta, R.
Tripakis, S.
Varaiya, P.
2001

The wireless token ring protocol (WTRP) is a medium access control (MAC) protocol for wireless networks in intelligent transportation systems (ITS). It supports quality of service (QoS) in terms of bounded latency and reserved bandwidth. The WTRP is efficient in the sense that it reduces the number of re-transmissions due to collisions. It is fair in the sense that each station takes a turn to transmit and is forced to give up the right to transmit after transmitting for a specified amount of time. It is a distributed protocol that supports many topologies since not all stations need to be...

Decentralized Error-Dependent Transmission Control for Model-Based Estimation Over a Multi-Access Network

Huang, Ching-Ling
Sengupta, Raja
2008

This paper is motivated by the estimation problem and active safety design for ITS. We investigate the performance of model-based estimation over a multi-access network and emphasizes on asymptotic time-averaged MSE while using error-dependent transmission control. The performance of this decentralized policy is analyzed and an improved policy is also proposed to achieve robustness in a shared channel. Our results suggest that, while designing communication logic for vehicular safety applications, dynamics of the system and channel congestion should be considered at the same time.

Quantified Traveler: Travel Feedback Meets the Cloud to Change Behavior

Sengupta, Raja
Walker, Joan L.
2015

Halting climate change will require a concerted effort to reduce emissions from on-road vehicles. While significant progress has been made to improve vehicle efficiency and reduce CO 2 emissions, surface transportation accounted for half the increase in US green-house gas (GHG) emissions over the past two decades. Today, surface transportation accounts for 24 percent of all US emissions. Automobile improvements alone will not be sufficient to meet federal and state emissions targets; policy makers also need to identify solutions that reduce the demand for car travel. Information technology...

Real-time Estimation of a Markov Process Over a Noisy Digital Communication Channel

Xu, Qing
Sengupta, Raja
2011

We study the real-time estimation of a Markov process over a memoryless noisy digital communication channel. The goal of system design is to minimize the mean squared estimation error. We first show the optimal encoder and decoder can be memoryless in terms of the source symbols. We then prove the optimal encoder separates the real space with hyperplanes. In the case of the binary symmetric channel and scalar source, the optimal encoder can be a threshold. A recursive algorithm is given to jointly find a locally optimal encoder and decoder for the binary symmetric channel. For a memoryless...

Scaling Laws for Cooperative Node Localization in Non-Line-of-Sight Wireless Networks

Ekambaram, Venkatesan
Ramchandran, Kannan
Sengupta, Raja
2011

We study the problem of cooperative node localization in non-line- of-sight (NLOS) wireless networks and address design questions such as, "How many anchors and what fraction of line-of-sight (LOS) measurements are needed to achieve a specified target accuracy?". We analytically characterize the performance improvement in localization accuracy as a function of the number of nodes in the network and the fraction of LOS measurements. In particular, we show that the Cramer- Rao Lower Bound (CRLB) can be expressed as a product of two factors - a scalar function that depends only on the...