The Institute of Transportation Studies at UC Berkeley has supported transportation research at the University of California since 1948. About 50 faculty members, 50 staff researchers and more than 100 graduate students take part in this multidisciplinary program, which receives roughly $40 million in research funding on average each year. Alexandre Bayen, Professor of Civil and Environmental Engineering and Professor of Electrical Engineering and Computer Science, is its director.
These problem sets comprise a supplement to Fundamentals of Transportation and Traffic Operations (C. Daganzo, Pergamon, 1997). Academicians can also obtain a companion set of solutions by writing to "Institute of Transportation Studies, Publications Office, 109 McLaughlin Hall, University of California, Berkeley, CA 94720" or by sending e-mail to firstname.lastname@example.org.
Optimal Infrastructure System Maintenance and Repair Policies with Random Deterioration Model Parameters
Accurate facility deterioration models are important inputs for the selection of Infrastructure Maintenance, Repair, and Reconstruction (MR & R) policies. Deterioration models are developed based on expert judgment or empirical observations. These resources, however, might not be sufficient to accurately represent the performance of infrastructure facilities. Incorrect deterioration models may lead to wrong predictions of infrastructure performance and selection of inappropriate MR & R policies. This results in higher lifecycle costs. Existing infrastructure MR & R decisionmaking models assume that deterioration models represent the real deterioration process of infrastructure facilities. This assumption ignores the uncertainty in empiricallyderived facility deterioration models. This dissertation presents a methodology for selecting MR & R policies for systems of infrastructure facilities under uncertainty in the deterioration model parameters. It is assumed that inspections reveal the true conditions of facilities. Based on the inspection results, the deterioration model parameters can be updated to express the deterioration process more accurately. It is expected that more appropriate maintenance policies will be selected as a result. In the first part of this dissertation, it is assumed that facility inspections are performed at the beginning of every year. The model parameters are updated and MR & R policies are selected every year using the updated deterioration models. In the second part, the assumption is relaxed and alternate inspection frequencies are considered. In this case, the updates of the model parameters and the selection of optimal MR & R policies are executed only after an inspection. The results of the parametric analyses demonstrate that updating the deterioration models reduces the expected system costs. The results also show that relaxing the facility inspection frequency can reduce the total costs further.
This dissertation presents dynamic stochastic optimization models for Air Traffic Flow Management (ATFM) that enables decisions to adapt to new information on evolving capacities of National Airspace System (NAS) resources. Uncertainty is represented by a set of capacity scenarios, each depicting a particular time-varying capacity profile of NAS resources. We use the concept of a scenario tree in which multiple scenarios are possible initially. Scenarios are eliminated as possibilities in a succession of branching points, until the specific scenario that will be realized on a particular day is known. Thus the scenario tree branching provides updated information on evolving scenarios, and allows ATFM decisions to be re-addressed and revised. First, we propose a dynamic stochastic model for a single airport ground holding problem (SAGHP) that can be used for planning Ground Delay Programs (GDPs) when there is uncertainty about future airport arrival capacities. Ground delays of non-departed flights can be revised based on updated information from scenario tree branching. The problem is formulated so that a wide range of objective functions, including non-linear delay cost functions and functions that reflect equity concerns can be optimized. Furthermore, the model improves on existing practice by ensuring efficient use of available capacity without necessarily exempting long-haul flights. Following this, we present a methodology and optimization models that can be used for decentralized decision making by individual airlines in the GDP planning process, using the solutions from the stochastic dynamic SAGHP. Airlines are allowed to perform cancellations, and re-allocate slots to remaining flights by substitutions. We also present an optimization model that can be used by the FAA, after the airlines perform cancellation and substitutions, to re-utilize vacant arrival slots that are created due to cancellations. Finally, we present three stochastic integer programming models for managing inbound air traffic flow of an airport, when there is adverse weather impacting the arrival capacity of the airport along with its arrival fixes. These are the first models, for optimizing ATFM decisions, which address uncertainty of future capacities of multiple NAS resources.
This research describes field studies of how on-ramp metering can increase the capacity of freeway merges. Some effects of on-ramp metering have been known for a long time. We have known that on-ramp metering can 1) increase freeway flow and speed upstream of a merge; and 2) reduce system-wide delay by alleviating gridlock-causing queues that have blocked off-ramps. However, past studies have not conclusively shown that on-ramp metering can increase the maximum outflow (capacity) of freeway merges. The experiments conducted in the present study verify that on-ramp metering can increase freeway merge capacities. Detailed traffic data collected from videos for more than 30 rush periods at two merge bottlenecks unveil six major research findings: 1) merge capacity diminishes after merges became active bottlenecks; 2) the mechanism of "capacity drop" has been identified and was found to be reproducible across all days and it both sites. By metering the on-ramp in certain strategic ways, the capacity drop mechanism can be 3) reversed; and 4) even averted; 5) such metering strategies can be fully automated using loop detector measurements; and 6) control strategies other than ramp metering also hold promise for increasing merge capacities. These findings provide much-needed information concerning how to control freeway traffic. They also offer basis for more realistic theories of merging traffic flow.
Transportation Periodicals And Newsletters Currently Received At The Institute Of Transportation Studies Library, University Of California At Berkeley
This publication is intended to serve as a convenient reference to selected transportation periodicals and newsletters currently (2000) received by UC Berkeley's Harmer E. Davis Transportation Li-brary. This latest version of Transportation Periodicals and Newsletters represents a thourough revision of earlier editions (1989, 1993, and 1995) published under the same (or similar) title. The subject content of this listing reflects the subject strengths of the H.E. Davis Transportation Library: highways and traffic, air transportation, railroads, and urban transit. Water and pipeline modes are represented to a lesser extent. Collection emphasis at the Transportation Library is placed on planning, design, construction, and operations and most titles fall within this context. However, some titles in transportation business and economics do appear. While primary emphasis is placed on English language publications published in the United Sates, significant transportation journals from abroad are also included in the pages which follow.
This bibliography, containing over 650 entries, is intended to serve as a guide to the major sources of information on highways. While sources listed focus primarily on the United States and Canada, some international materials have been included. Though emphasis is on current publications, some materials of historical interest have also been included. Resources listed in the bibliography include both print and electronic materials, with many Internet sites falling within that latter category. The bibliography was a collaborative effort and was compiled by twelve members of the Transportation Division of the Special Libraries Association. The resultant bibliography is part of a larger Transportation Division project, a revised edition of the Division's multi-volume work, Sources of Information in Transportation. The full, multi-volume new edition (its 5th ) will be available in electronic format on the Internet, with a publication date of late 2001 anticipated. Information concerning the new edition of Sources of Information in Transportation may be found at the Division's website: http://www.library.nwu.edu/transportation/slatran/
This bibliography is intended to serve as a guide to sources of information in Intelligent Transportation Systems. While it focuses primarily on U.S. and Canadian publications, some international materials have been included. Emphasis is on current publications, however, some materials of historical interest have also been included. Although the term ITS (Intelligent Transportation Systems) is considered to be the more current terminology, the term IVHS (Intelligent Vehicle Highway Systems) has been retained and used when appropriate to reflect older publications of historical significance. This bibliography is based primarily on the holdings of the Harmer E. Davis Transportation Library at the Institute of Transportation Studies, University of California at Berkeley. References for electronic publications and web sites are current as of March 2001.
Estimating the producer surplus – the revenue above the average long-run cost – is an important part of social cost-benefit analyses of changes in petroleum use. This paper estimates the producer surplus associated with changes in gasoline fuel use in the United States, and then applies the estimates of producer surplus to two kinds of social cost-benefit analyses related to petroleum use: (1) estimating the wealth transfer from consumers to producers as a result of policies that affect oil use and oil imports to the US, and (2) comparing the actual average cost of gasoline with the average cost of environmentally superior alternatives to gasoline, such as hydrogen. Our results show that a 50% reduction in gasoline use in the US in 2004 would have saved the US $72 billion in producer surplus payments to foreign oil producers. Applying our estimates to the comparison of the social lifetime cost of hydrogen vehicles versus gasoline vehicles, we find that inconsistently counting producer surplus from a US national perspective while counting climate change damages from a global perspective can overstate the present value lifetime costs of gasoline vehicles by $2,200 to $9,800 per vehicle.
This paper presents a simple approximate procedure for traffic analysis that can be described geometrically without calculus. The procedure, which is graphically intuitive, operates directly on piecewise linear approximations of the N-curves of cumulative vehicle count. Because the N-curves are both readily observable and of direct interest for evaluation purposes (e.g., they yield the total vehicle-hours and vehicle-miles of travel in a time interval, and the vehicular accumulation as a function of time) the predictions made with this method should be practical and easy to test.
Inflation and increased fuel economy have reduced the buying power of the revenues collected from state and federal motor fuel taxes. Because fuel taxes are almost always collected on a per-gallon basis, in most states they must be raised by specific acts of the legislature and it is becoming increasingly difficult to find the political support necessary to raise them. A number of states have experimented with fuel taxes that adjust automatically by being indexed to the price of gasoline, to the consumer price index, or to some indicator of highway construction and maintenance costs. This paper reviews experience with indexed motor fuel taxes in the United States, and finds that in many cases indexed taxes have failed to produce the anticipated results because declines in fuel prices often cause declines in indexed fuel taxes. Indexing gas tax rates to the Consumer Price Index appears to be the best way of insuring that fuel tax revenues keep pace with inflation. Fuel taxes are the mainstay of transportation finance in the United States. The federal government and every state levy taxes on gasoline and diesel fuel. Motor fuel taxes have much to recommend them fiscally, politically, and administratively. First and foremost, as a "user fee" this tax is widely regarded to be inherently fair. It can be assumed that we benefit from the transportation system in proportion to the extent to which we use it, and motor fuel taxes charge us roughly in proportion to our use of the road and highway system. Furthermore, the tax is paid by motorists in small increments and is relatively hidden in the sales price of motor fuel. This has tended to minimize organized public opposition to it. The tax is also easy to administer and collect from both the taxpayer's and the government's point of view. The motor fuel tax is usually collected from fuel distributors rather than from retailers or consumers. This minimizes opportunities for evasion and reduces the cost of collection to an historical average of one-half of one percent of tax proceeds. By contrast, prior to the advent of electronic toll collection, highway tolls could often involve collection and administrative costs that amounted to as much as twenty percent of the proceeds. As motor fuel consumption has soared over the past eight decades, so have tax proceeds, enabling users of the nation's highway system to finance its construction and maintenance.
2001: An Airspace Odyssey SUMMARY PROCEEDINGS OF THE 2001 AIRPORT NOISE SYMPOSIUM AND AIRPORT AIR QUALITY SYMPOSIUM
These proceedings summarize the presentations made at the 16th Airport Noise Symposium and 2nd Airport Air Quality Symposium, organized by the Technology Transfer Program of the Institute of Transportation Studies (ITS) and held in San Diego, California, from February 25 to March 2, 2001. The presentation slides for many of the presentations at both symposia are available on the ITS Technology Transfer Program website at .
The symposia were organized in conjunction with the National Center of Excellence for Aviation Operations Research, the Federal Aviation Administration, the Federal Interagency Committee on Aviation Noise, and the Port of San Diego, and with the active support and assistance of the individuals and organizations represented on the Symposia Program Committee, listed at the end of these proceedings.
This paper proves that kinematic wave (KW) problems with concave (or convex) equations of state can be formulated as calculus of variations problems. Every well-posed problem of this type, no matter how complicated, is reduced to the determination of a shortest tree in a relevant region of spacetime where cost is predefined. A duality between KW theory and /least cost networks is thus unveiled. In the new formulation space-time curves that constrain flow, such as sets of moving bottlenecks, become space-time shortcuts. These shortcuts become part of the network and affect the nature of the solution but not the speed with which it can be obtained. Complex boundary conditions are naturally handled in the new formulation as constraints/shortcuts of this type.
This paper shows how to reduce the bullwhip effect by introducing advance demand information (ADI) into the ordering schemes of supply chains. It quantifies the potential costs and benefits of ADI, and demonstrates that they are not evenly distributed across the chain. Therefore, market-based strategies to re-distribute wealth without penalizing any supplier are presented. The paper shows that if a centralized operation can eliminate the bullwhip effect and reduce total cost, then some of this reduction can also be achieved with decentralized negotiation schemes. Their performance is evaluated under different modes of probabilistic supplier behavior. For some forms of behavior the optimum is reached. But if suppliers are greedy and impatient the expected gain in wealth is relatively small. This is a case of economic "market failure."
We consider a Generalized, Multiple Depot Hamiltonian Path Problem (GMDHPP) and show that it has an algorithm with an approximation ratio of 3/2 if the costs are symmetric and satisfy the triangle inequality. This improves on the 2-approximation algorithm already available for the same.
Optimal cordon-metering rates are obtained using Macroscopic Fundamental Diagrams in combination with flow conservation laws. A model-predictive control algorithm is also used so that time-varying metering rates are generated based on their forecasted impacts. Our scalable algorithm can do this for an arbitrary number of cordoned neighborhoods within a city. Unlike its predecessors, the proposed model accounts for the constraining effects that cordon queues impose on a neighborhood's circulating traffic. It does so at every time step by approximating a neighborhood's street space occupied by cordon queues, and re-scaling the MFD downward to describe the state of circulating traffic that results. The model is also unique in that it differentiates between saturated and under-saturated cordon-metering operations. Computer simulations show that these enhancements can substantially improve the predictions of both, the trip completion rates in a neighborhood and the rates that vehicles cross metered cordons. Optimal metering policies generated as a result are similarly shown to do a better job in reducing the Vehicle Hours Traveled in a city. The VHT reductions stemming from the proposed model and from its predecessors differed by as much as 18%.
Public transit investments are a large and growing share of all transportation investments in the state of California, and such critical investments should be evaluated partly on their economic benefits. Taking such benefits into account could alter investment, service, and service restructuring decisions taken by transit agencies in the state. The relationship of public transportation to economic productivity, and spatial patterns of industrial location, is understudied. This project investigated how changes in rail transit service in California metropolitan areas (Los Angeles, the San Francisco Bay Area, and San Diego) are associated with firm clustering by industry and with commercial property values. A mixed methods approach was used. One strand of the research involved first, describing location patterns by industry according to transit access, and second, quantitatively modeling the relationship between transit access and (a) employment densification by industry and (b) commercial property values, using instrumental variables techniques with dynamic panel modeling in order to better infer causal relationships. The second strand consisted of interviews and other qualitative research aimed at finding possible explanations for firm location and expansion, and firm productivity. The quantitative research found that rail development generally promotes employment agglomeration and increased land value, but the magnitude of such effects differs across regions. San Francisco County had the highest employment densification and land value associated with rail proximity, while the LA region also had a relatively strong relationship between rail access and both employment density and property value. Rail access in the southern part of the San Francisco Bay Area, where Silicon Valley is situated, had a small relationship with employment densification but a positive effect on land values. On the contrary, rail development in the San Diego region was positively associated with employment density, but negatively associated with land value appreciation. Our interviews were consistent with these quantitative findings, and suggested that the differences between regions are due to differences in historical land development and use patterns as well as urban land regulations. In the San Francisco Bay Area, developers and real estate brokers report that rail transit plays the greatest role in the City of San Francisco, with relatively weak importance in Silicon Valley due to higher parking provisions and employer-provided transportation amenities such as shuttles. In the Los Angeles metropolitan area, rail transit is most highly valued in the dense downtown Los Angeles area, and is perceived to be playing an increasingly important role across the region as in places where traffic congestion is high and increasing.
Transfers are a major source of travel time variability for transit passengers. Coordinating transfers between transit routes in real time can reduce passenger waiting times and travel time variability, but these benefits need to be contrasted with the delays to on-board and downstream passengers, as well as the potential for bus bunching created by holding buses for transfers. We developed a dynamic holding strategy for transfer coordination based on control theory. We then obtained the optimal control strategy, where maximum holding time is a function of real-time estimates of bus arrivals and passengers and the uncertainty in these estimates. Total travel time (waiting plus in-vehicle) with the optimal control is found to be globally less than or equal to total travel time without control when uncertainty is bounded. The time savings from transfer coordination increase with the ratio of transferring to through passengers but diminish as uncertainty in the real-time estimates of bus arrivals increases. Field observations at a multimodal transfer point in Oakland show that the proposed control strategy could reduce net transfer delay by 30-39% in a real-world scenario. The data collected also confirm that the upper bound on uncertainty in bus arrivals can be satisfied with existing bus location technology. We conclude with a discussion of complementary measures, such as the provision of real-time information at transfer points and conditional signal priority, which could allow coordination to be applied in more cases.
Public transit systems with efficient designs and operating plans can reduce greenhouse gas (GHG) emissions relative to low-occupancy transportation modes, but many current transit systems have not been designed to reduce environmental impacts. This motivates the study of the benefits of design and operational approaches for reducing the environmental impacts of transit systems. For example, transit agencies may replace level-of-service (LOS) by vehicle miles traveled (VMT) as a criterion in evaluating design and operational changes. Previous studies have demonstrated in an idealized singletechnology transit system the potential of reducing GHG emissions by lowering the transit level-of-service (LOS) provided to the users. In this research, we extend the analysis to account for a more realistic case: a transit system with a hierarchical structure (trunk and feeder lines) providing service to a city where demand is elastic. By considering the interactions between the trunk and the feeder systems, the study provides a quantitative basis for designing and operating integrated urban transit systems that can reduce GHG emissions and costs to both transit users and agencies. The study shows that highly elastic transit demand may cancel emission reduction potentials resulting from lowering LOS, due to demand shifts to lower occupancy vehicles, causing unintended consequences. However, for mass transit modes, these potentials are still significant. Transit networks with buses, bus rapid transit or light rail as trunk modes should be designed and operated near the cost-optimal point when the demand is highly elastic, while this is not required for metro. We also find that the potential for unintended consequences increases with the size of the city. The results are robust to uncertainties in the costs and emissions parameters. The study also includes a discussion of a current transit system. Since many current transit systems have not yet been optimally designed, it should be possible to reduce their GHG emissions without sacrificing the LOS. A case study of the MUNI bus system in San Francisco is used to validate this conjecture. The analysis shows that reductions in GHG emissions can be achieved when societal costs are reduced simultaneously. The cost-optimal MUNI bus system has a societal cost of 0.15 billion $/year and emits 1680 metric tons of greenhouse gases. These figures only amount to about half of the cost and a third of the emissions in the current MUNI bus system. The optimal system has a lower spatial availability but a higher temporal availability of bus service than the current system, which highlights the potential benefits of providing more frequent express bus services.