Roads/Highways

Lessons learned from the installation and operation of Northern California's first 70-MPa hydrogen fueling station

Tim Lipman
Maggie Witt
Matthew Elke
2013

A hydrogen dispensing facility capable of providing rapid 70-MPa vehicle fills became operational in May 2011 as the first such hydrogen dispensing facility in Northern California. The facility is operated by the University of California – Berkeley in support of fuel cell vehicle research with automakers, regional and state agencies, and industrial groups. In addition to storing and dispensing high-pressure hydrogen fuel, the station also incorporates a number of key advances in hydrogen refueling system capabilities, including novel fuel pre-cooling, fuel storage, and system safety...

Hydrogen Energy Stations: Poly-Production of Electricity, Hydrogen, and Thermal Energy

Tim Lipman
Cameron Brooks
2006

The "hydrogen energy station" is one method of hydrogen production at small and medium scales. Unlike more conventional hydrogen station designs where hydrogen is simply delivered or produced on-site with a fuel "reformer" or water electrolyzer and then compressed and dispensed, energy stations would provide multiple functions in the same facility. They would integrate systems for production of electricity for 1) local uses and/or the utility grid, 2) re-use of thermal energy "waste heat" for building heating/cooling needs, and 3) purified hydrogen for refueling vehicles.Hydrogen energy...

An Assessment of the Near-Term Costs of Hydrogen Refueling Stations and Station Components

Tim Lipman
Jonathan Weinert
2006

Interest in hydrogen as a transportation fuel is growing in California. Plans are underway to construct a “Hydrogen Highway” network of stations across the state to stimulate fuel cell vehicle deployment. One of the key challenges in the planning and financing of this network is determining the costs of the stations. The purpose of this report is to examine the near-term costs of building hydrogen stations of various types and sizes. The costs for seven different station types are analyzed with respect to size, siting factors, and operating factors. The first section of the report reviews...

Driving California’s Transportation Emissions to Zero

Austin Brown
Daniel Sperling
Bernadette Austin
J. R. DeShazo
Lew Fulton
Tim Lipman
Colin Murphy
Jean Daniel
Gil Tal
Carolyn Abrams
Debapriya Chakraborty
Daniel Coffee
Sina Dabag
Adam Davis
Mark Delucchi
Kelly Fleming
Kate Forest
Juan Carlos Garcia Sanchez
Susan Handy
Michael Hyland
Alan Jenn
Seth Karten
Blake Lane
Michael Mackinnon
Elliot Martin
Marshall Miller
Monica Ramirez-Ibarra
Stephen Ritchie
Sara Schremmer
Joshua Segui
Susan Shaheen
Andre Tok
Aditya Voleti
Julie Witcover
Allison Yang
2021

The purpose of this report is to provide a research-driven analysis of options that can put California on a pathway to achieve carbon-neutral transportation by 2045. The report comprises thirteen sections. Section 1 provides an overview of the major components of transportation systems and how those components interact. Section 2 discusses the impacts the COVID-19 pandemic has had on transportation. Section 3 discusses California’s current transportation-policy landscape. These three sections were previously published as a synthesis report. Section 4 analyzes the different carbon scenarios...

The Spatial Evolution of Traffic Under the Two Wave Speed Assumption: A Shortcut Procedure and Some Observations

Carlos Daganzo
1993

This paper describes the behavior of traffic in a homogeneous highway according to the hydrodynamic theory, in the special casewhere the flow-density relationship is triangular; i.e. when only two wave velocities exist. It presents an exact formula thatpredicts the vehicle that would be found at position x at time t, given the locations of all the vehicles at time zero. The formula, which does not require identification of the vehicle positions at intermediate times, automatically accounts for the creation and dissipation of any shocks. It can be used to calculate system performance...

The Cell Transmission Model. Part I: A Simple Dynamic Representation of Highway Traffic

Carlos Daganzo
1993

This paper presents a simple representation of traffic on a highway with a single entrance and exit. The representation can be used to predict traffic's evolution over time and space, including transient phenomena such as the building, propagation and dissipation of queues. The easy-to-solve difference equations used to predict traffic's evolution are shown to be the discrete analog of the differential equations arising from a special case of the hydrodynamic model of traffic flow. The proposed method automatically generates appropriate changes in density at locations where the...

Effect of Modeling Assumptions on Evolution of Queues in a Single Corridor

Carlos Daganzo
Lin, Wei-Hua
1994

A qualitative description is presented of queuing patterns under an idealized scenario analogous to the evolution of traffic congestion during the morning peak hour in a long corridor leading to a single destination. The simplicity of the scenario allows the results to be verified independently by hand. Initially the corridor is assumed to consist of a single freeway. Traffic is generated at the freeway's many on-ramps during a short period and then is assumed to subside. Capacity limitations create queues on the ramps and the freeway, whose evolution is then described. A special...

A Continuum Theory of Traffic Dynamics for Freeways with Special Lanes

Carlos Daganzo
1995

This paper presents a generalized theory of kinematic waves for freeways with two vehicle types and a set of lanes reserved for one of the vehicle classes. The theory is not restricted to freeways on which the special lanes are clearly identified by signs and pavement markings; e.g. for high occupancy vehicles. It may also apply if the restrictions are self-imposed, such as would occur on a freeway segment upstream of a busy off-ramp where the existing traffic naturally avoids the ‘far-side’ lanes. Of particular interest are oversaturated time periods because the original theory of...

Evaluation of Alternative AHS System Operating Concepts

Carlos Daganzo
Cayford, Randall
Lin, Wei-Hua
1995

This paper focuses on technical and economic investigations of automated highway systems (AHS). It attempts to show that the actual viable implementation opportunities for AHS are scarce. The paper begins with an investigation that looks at realistic estimates of AHS capacity, interfacing with the local street system, and storage issues. The authors then identify criteria to help in determining which types of urban areas might be potential candidates for AHS technologies. Certain locations where AHS might be beneficial are identified, but doubt is raised regarding the extent of the...

Steady State Conditions on Automated Highways

del Castillo, Jose M.
Lovell, David J.
Carlos Daganzo
1995

This paper is concerned with technical investigations of traffic operations on automated highways. Estimates are made of the steady-state capacity of such freeways, paying particular attention to the effect of entry and exit maneuvers. The possibility of scheduling departing vehicles appropriately into platoons to minimize extraneous maneuvers is investigated. Characteristics of urban areas likely to be candidates for automated freeways are discussed, and some shortcomings of automated freeways, vis-à-vis conventional freeways, are pointed out. Finally, some areas of future research needs...