Book of the Week: Introduction to Air Transport Economics

 

We're starting a new series here highlighting different books from our collection. This week we're focusing on a new book about aviation. Introduction to Air Transport Economics: From Theory to Application (Second Edition) by Bijan Vasigh, Ken Fleming, and Thomas Tacker is published by Ashgate

The book presents the fundamentals of the aviation industry with a foundation of underlying economic concepts. It also touches upon policy, institutional structures, and market forces (such as anti-trust considerations) that affect the aviation industry.  New to aviation? This book can help you get started. It is waiting on our New Book Shelf to be checked out by you today! 

10 Things You Should Know: Thing 2 - Use OskiCat!

Thing 2 on our 10 Things You Should Know About The ITS Library is a classic in the libraries - Use OskiCat

What's an OskiCat? It's not really a cat, it's the catalog here at UC Berkeley.  Use it search for books, journals (not articles - those are in TRID!), course reserves, or other collections. It's the tool you want to use to see if a physical copy of it exists on campus. To find a physical copy beyond the campus use Melvyl. That's another catalog which includes holdings for all UC campuses and beyond. 

 

10 Things You Should Know: Thing 1 - Use TRID!

Welcome back to school! To kick of the semester, we'd like to remind everybody about 10 Things You Should Know About the ITS LibraryThing 1 is perhpas the most important advice we have for getting started with your research: Use TRID!

What's TRID? It's a transportation research database from TRB and ITRD, and the place to start your transportation research.  It contains journal articles, tech reports, conference proceedings, and research projects. Most of the records include links to online full-text versions. 

But what about the catalog? Well OskiCat is great for books and finding out if we physically have something (or have access to something), but for most new transportation research it is inadequate. OskiCat does not contain articles, so you'll miss out on much of the current literature. 

For example, if you search TRID for the keyword "parking pricing", you receive 1103 results.

Using the same search in OskiCat retrieves only 66 results

So if you're just getting started, use TRID. 

 

Goodbye old Bay Bridge, Hello new Bay Bridge

Bay Bridge Under Construction

Starting this evening, the Bay Bridge will close and reopen Tuesday September 3 at 5:00 am. Over the weekend the final touches will be put on the new Eastern Span and on Tuesday morning, you can have a new driving experience across that span. You will no longer have to contend with the S-Curve. There will be bicycle and pedestrian access! (Though only to Treasure Island... and even that isn't quite ready yet.) The old span will still be around for some time though, as it's going to take 3 years to dismantle

Of course traffic will be a mess. 511.org has been suggested to help with trip planning and BART will be running 24 hours over the weekend. Transit is usually regarded as an effective tool to mitigate the impact of these sorts of closures. Could this sort of disrpuption lead to policy and travel behavior change?

Oh and we can't forget the launch of Bay Area Bikeshare

If you were lucky enough to go on one of the bridge tours this weekend, have fun! Everybody else, hold tight. 

Urban Gridlock

Chicago Gridlock

Gridlock is a fact of life in urban areas. Why is that? A new study explores the characteristics of urban gridlock, to better understand the condition and ways to ease congestion. From Transportation Research Part C: Emerging Techonologies, "Urban network gridlock: Theory, characteristics, and dynamics" by Hani S. Mahmassani, Meead Saberi, and Ali Zockaie tackles the issue. 

This study explores the limiting properties of network-wide traffic flow relations under heavily congested conditions in a large-scale complex urban street network; these limiting conditions are emulated in the context of dynamic traffic assignment (DTA) experiments on an actual large network. The primary objectives are to characterize gridlock and understand its dynamics. This study addresses a gap in the literature with regard to the existence of exit flow and recovery period. The one-dimensional theoretical Network Fundamental Diagram (NFD) only represents steady-state behavior and holds only when the inputs change slowly in time and traffic is distributed homogenously in space. Also, it does not describe the hysteretic behavior of the network traffic when a gridlock forms or when network recovers. Thus, a model is proposed to reproduce hysteresis and gridlock when homogeneity and steady-state conditions do not hold. It is conjectured that the network average flow can be approximated as a non-linear function of network average density and variation in link densities. The proposed model is calibrated for the Chicago Central Business District (CBD) network. We also show that complex urban networks with multiple route choices, similar to the idealized network tested previously in the literature, tend to jam at a range of densities that are smaller than the theoretical average network jam density. Also it is demonstrated that networks tend to gridlock in many different ways with different configurations. This study examines how mobility of urban street networks could be improved by managing vehicle accumulation and redistributing network traffic via strategies such as demand management and disseminating real-time traveler information (adaptive driving). This study thus defines and explores some key characteristics and dynamics of urban street network gridlocks including gridlock formation, propagation, recovery, size, etc.

The full paper can be found here.

Rebalancing and Bikeshare

The mythical #DivvyRed

Is this the summer of Bikeshare? Divvy Bikes in Chicago launched last month. CitiBikes in New York City launched around Memorial Day. Any time now Bay Area Bike Share will be launching in San Francisco and on then Peninsula. 

The issue of having bikes where people want them is a perennial issue for bikeshare systems. "Rebalancing" is the act of moving inventory around to match demand and travel patterns. This map provides realtime visualizations of the demand of bikeshare systems around the world. Researchers are working on solving the rebalancing problem

A new article from EURO Journal on Transportation and Logistics works to develop a model for rebalancing. "Static repositioning in a bike-sharing system: models and solution approaches" by Tal Raviv, Michal Tzur, and Iris A. Forma, looks at how rebalancing or repositioning can help bikeshare systems.

Bike-sharing systems allow people to rent a bicycle at one of many automatic rental stations scattered around the city, use them for a short journey and return them at any station in the city. A crucial factor for the success of a bike-sharing system is its ability to meet the fluctuating demand for bicycles and for vacant lockers at each station. This is achieved by means of a repositioning operation, which consists of removing bicycles from some stations and transferring them to other stations, using a dedicated fleet of trucks. Operating such a fleet in a large bike-sharing system is an intricate problem consisting of decisions regarding the routes that the vehicles should follow and the number of bicycles that should be removed or placed at each station on each visit of the vehicles. In this paper, we present our modeling approach to the problem that generalizes existing routing models in the literature. This is done by introducing a unique convex objective function as well as time-related considerations. We present two mixed integer linear program formulations, discuss the assumptions associated with each, strengthen them by several valid inequalities and dominance rules, and compare their performances through an extensive numerical study. The results indicate that one of the formulations is very effective in obtaining high quality solutions to real life instances of the problem consisting of up to 104 stations and two vehicles. Finally, we draw insights on the characteristics of good solutions.

The full paper can be found here

Crowding in transit: How does it effects on riders, operations and demand.

SCRTD Crowded Bus Stop RTD_1131_13

Crowded bus stops and subway stations, which beget crowded buses and trains, are a part of riding transit. ITS Berkeley researchers are exploring how this effects rider attitudes

A new article from Transportation Research Part A: Policy and Practice examines this issue. In "Crowding in public transport systems: Effects on users, operation and implications for the estimation of demand," researchers from Chile and Australia look at the effects of crowding on speed, waiting times, travel time reliability, and route choice. 

The effects of high passenger density at bus stops, at rail stations, inside buses and trains are diverse. This paper examines the multiple dimensions of passenger crowding related to public transport demand, supply and operations, including effects on operating speed, waiting time, travel time reliability, passengers’ wellbeing, valuation of waiting and in-vehicle time savings, route and bus choice, and optimal levels of frequency, vehicle size and fare. Secondly, crowding externalities are estimated for rail and bus services in Sydney, in order to show the impact of crowding on the estimated value of in-vehicle time savings and demand prediction. Using Multinomial Logit (MNL) and Error Components (EC) models, we show that alternative assumptions concerning the threshold load factor that triggers a crowding externality effect do have an influence on the value of travel time (VTTS) for low occupancy levels (all passengers sitting); however, for high occupancy levels, alternative crowding models estimate similar VTTS. Importantly, if demand for a public transport service is estimated without explicit consideration of crowding as a source of disutility for passengers, demand will be overestimated if the service is designed to have a number of standees beyond a threshold, as analytically shown using a MNL choice model. More research is needed to explore if these findings hold with more complex choice models and in other contexts.

The full article can be found here

Metro ExpressLanes preliminary report

Harbor Freeway Transitway

Last week the Los Angeles County Metropolitan Transportation Autority, or LA Metro, released the preliminary data from the ExpressLanes program. ExpressLanes is a demonstration project with Metro and Caltrans that implemented toll lanes on I-10 and I-110 in conjunction with improved transit and carpool options along those corridors. 

While the demonstration period is not yet over, there have already been noticable increases in transit ridership and vanpools along the corridor. To explore more of the data and figures, the full report can be found here

Bottlenecks and the evening commute.

Motion

During the evening commute there are often bottlenecks as people try to get home on fixe routes with finite capacity. Vickrey's "Congestion Theory and Transport Investment" (1969) decribes the problem of commuters trying to pass the bottleneck. A recent paper, "The evening commute with cars and transit: Duality results and user equilibrium for the combined morning and evening peaks" by Eric Gonzales and Carlos Daganzo tackles the commute problem looking at both the evening and morning commute, since mode travel decisions are often made based upon the travel needs for the whole day. 

The paper then considers both the morning and evening peaks together for a single mode bottleneck (all cars) with identical travelers that share the same wished times. For a schedule penalty function of the morning departure and evening arrival times that is positive definite and has certain properties, a user equilibrium is shown to exist in which commuters travel in the same order in both peaks. The result is used to illustrate the user equilibrium for two cases: (i) commuters have decoupled schedule preferences in the morning and evening and (ii) commuters must work a fixed shift length but have flexibility when to start. Finally, a special case is considered with cars and transit: commuters have the same wished order in the morning and evening peaks. Commuters must use the same mode in both directions, and the complete user equilibrium solution reveals the number of commuters using cars and transit and the period in the middle of each rush when transit is used.

The whole paper can be found here

#BARTSTRIKE

 

At midnight July 1 2013, after failed negotiations between BART and its two main unions, BART workers went on strike. The strike has disrupted transportation throughout much of the Bay Area-  increasing commute times and traffic congestion. Many commuters are turning to the ferries, casual carpool, and rideshare. The more adventurous have opted for helicopters or yachts. While there has been the predicted mix of frustration, criticism, and selfpromotion on Twitter via #BARTstrike, it's still too early to gague the real impact of the strike on transportation. Some projections estimate the econmic impact to be $73 million a day as well as 16 million pounds of carbon. Some clues might be gleaned from the recently published, Subways, Strikes, and Slowdowns: The Impacts of Public Transportation on Traffic Congestion. Using data from the 2003 transit worker strike in Los Angeles, researchers show that transit relieves traffic congestion

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