Articles

Everybody loves bus bunching.

Corporation Atlanteans at Moreton Shore

Or more realistically, everybody loves to complain about bus bunching - when two or more buses (usually on the same line) should be evenly spaced out, but are right behind one another. Here around UC Berkeley AC Transit's 51b in the line most people complain about bunching (they're working on it!), but every transit systems has its own problem line(s). 

Earlier this week WBEZ's Curious City examines bus bunching in Chicago. They provide an easy to understand animation that demonstrates how minor service delays cascade to bus bunching. Bookmark it to share with your friends next time they lament about the topic. 

The topic is also beloved by transit researchers, particularly at ITS Berkeley. From systematic analysis of why bunching occurs to ways to solve the problem. And as always, you can find more research on bus bunching at TRID

Everybody has an opinion on reclining airplane seats

Open Seating

Recently a flight from LGA to JAX was diverted due to passengers engaged in a seat reclining battle. It was the latest in a string of diverted flights stemming from passenger disruptions over the right to recline. A flight from EWR to DEN was diverted to ORD because a passenger used the Knee Defender to prevent the seat in front of them to recline. A recent flight from MIA to CDG was diverted to BOS after a passenger became upset when the seat in front of them reclined, and they lunged at a flight attendant. 

There is yet to be agreed upon rules for airplane seat reclining. Many say it boils down to being civil. Others are calling for reclining seats to be banned from airplanes because it's been demonstrated that passengers can't be civil.  Even Miss Manners has weighed in - she blames airlines for installing seats so closely together that nobody is happy. 

Today on Slate, Christopher Buccafusco and Chris Sprigman look at the economics of seat reclining. How much would you pay for the person in front of you not to recline? How much would you pay for the right to recline? They conducted an online survey to answer those questions, and they found out:

Recliners wanted on average $41 to refrain from reclining, while reclinees were willing to pay only $18 on average. Only about 21 percent of the time would ownership of the 4 inches change hands.
...
When we flipped the default—that is, when we made the rule that people did not have an automatic right to recline, but would have to negotiate to get it—then people’s values suddenly reversed. Now, recliners were only willing to pay about $12 to recline while reclinees were unwilling to sell their knee room for less than $39. Recliners would have ended up purchasing the right to recline only about 28 percent of the time—the same right that they valued so highly in the other condition.

They go on to say that this is basically the "endowment effect" as described in the 1990 paper by (Berkeley professor and Nobel laureate) Daniel Kahneman, Jack L. Knetsch and Richard H. Thaler, "Experimental Tests of the Endowment Effect and the Coase Theorem."

Decreasing seat size is just another way airlines engage in revenue management, along with itemized fees for everything. Airlines are already using dynamic pricing for fares. They also employ tactics to maximize flight frequency and aircraft size, though this can often lead to flight delays (which often results in higher fares). The boarding procedure is another area where airlines can be more cost effective, minimizing the time to board and turnaround time.

But will any of that get you more leg room on your next flight? 

What's the difference between people who use taxis and people who use ridesourcing in SF?

Proposed CPUC regulations improve consumer protection for Uber, Lyft and Sidecar

It seems like every week the two largest ridesourcing/TNC/ridesharing companies, Uber and Lyft, are in the news. This week featured stories about the two companies opposing a California state legislature bill mandating insurance for drivers, Uber's efforts to sabbotage Lyft with burner phones, and that both operations are now basically commodoties and not really that different from one another. 

Which makes this new UCTC paper all the more timely. 

In App-Based, On-Demand Ride Services: Comparing Taxi and Ridesourcing Trips and User Characteristics in San Francisco, Lisa Rayle (a 2014 Eisenhower Graduate Fellowship recipient) et al examine who uses these ridesourcing apps, and how they relate to more traditional taxi or transit riders. 

The rapid growth of on-demand ride services, or ridesourcing, has prompted debate among policy makers and stakeholders. At present, ridesourcing’s usage and impacts are not well understood. Key questions include: how ridesourcing and taxis compare with respect to trip types, customers, and locations served; whether ridesourcing complements or competes with public transit; and potential impacts on vehicle miles traveled. We address these questions using an intercept survey. In spring 2014, 380 complete surveys were collected from three ridesourcing “hot spots” in San Francisco. Survey results are compared with matched-pair taxi trip data and results of a previous taxi user survey.

The findings indicate ridesourcing serves a previously unmet demand for convenient, point-to-point urban travel. Although taxis and ridesourcing share similarities, the findings show differences in users and the user experience. Ridesourcing wait times are markedly shorter and more consistent than those of taxis, while ridesourcing users tend to be younger, own fewer vehicles and more frequently travel with companions. Ridesourcing appears to substitute for longer public transit trips but otherwise complements transit. Impacts on overall vehicle travel are ambiguous. Future research should build on this exploratory study to further understand impacts of ridesourcing on labor, social equity, the environment, and public policy.

The full paper can be found here

Bikeshare as Public Transit

Nice Ride Minnesota

As bikeshare systems grow, mature, and become quite common, researchers are beginning to answer some fundamental questions about bikeshare. Are bikeshare cyclists fundamentally different from regular cyclists? What about riders wearing helmets? How does weather affect bikeshare trips? How do bikeshare users integrate with other modes?

What about bikeshare as public transit?

That's what TSRC researchers Elliot Martin and Susan Shaheen have asked in their forthcoming article, "Evaluating public transit modal shift dynamics in response to bikesharing: a tale of two U.S. cities" in Journal of Transport Geography. They conclude that:

The modal shift to and from public transit has shown an intriguing degree of variation within and across cities, meriting further exploration in this paper. The authors found, through mapping the modal shifts reported by members, that shifts away from public transit are most prominent in core urban environments with high population density. Shifts toward public transit in response to bikesharing appear most prevalent in lower density regions on the urban periphery.

The full article can be found here. Or your can read an overview from CityLab

Celebrating Independence Day!

Where baby freeways come from

Tomorrow is Independence Day here in the United States, whi means the library (and the whole UC Berkeley campus) will be closed in observance of the Federal holiday. 

It also means holiday traffic as people head out of town for a long weekend, outdoor recreation, or to fireworks displays.  Holiday weekends tend to see an over-representation of fatal and injury crashes on the roadways, largely due increased drunk driving. Increased impaired-driving enforcement has helped reduce crash fatalities in the United States. Checkpoints could be even more effective with location optimization modeling

So have a festive and safe weekend. Don't drive impared. We'll see you next week!

Examining Electric Vehicle Parking

Electric Vehicle Parking

Electric vehicle (EV) public parking has been rolling out in Berkeley but got a boost recently with station installed at both Whole Foods. The city is slated to get more municipal charging stations soon, including a pilot to look at curbside charging stations

There are mixed opinions about EV public parking options, with concerns about location and demand. Researchers are looking at activity models to overcome public perception and be more effective in urban areas. A new article from Transportation Research Part A: Policy and Practice continues the discourse. "Electric vehicle parking in European and American context: Economic, energy and environmental analysis," by Marta V. Faria, Patrícia C. Baptista, and Tiago L. Farias, applies a methodology for the placement of EV parking to Lisbon, Madrid, Minneapolis and Manhattan. They conclude:

This research confirms that the success of deploying an EV charging stations infrastructure will be highly dependent on the price the user will have to pay, on the cost of the infrastructure deployed and on the adhesion of the EV users to this kind of infrastructure. These variables are not independent and, consequently, the coordination of public policies and private interest must be promoted in order to reach an optimal solution that does not result in prohibitive costs for the users.

The full article can be read here.  

 

New Article: Macroscopic Fundamental Diagram and Public Transport

Changing Course in Urban Transport

A brand new article in Transportation Research Part C: Emerging Technologies examines a macroscopic fundamental diagram (MFD) and how it is applied to bi-modal urban networks. "A three-dimensional macroscopic fundamental diagram for mixed bi-modal urban networks," by (ITS alum) Nikolas Geroliminis, Nan Zheng,and Konstantinos Ampountolas investigates existence of a three-dimensional vehicle-flow MFD for bi-modal network.

Recent research has studied the existence and the properties of a macroscopic fundamental diagram (MFD) for large urban networks. The MFD should not be universally expected as high scatter or hysteresis might appear for some type of networks, like heterogeneous networks or freeways. In this paper, we investigate if aggregated relationships can describe the performance of urban bi-modal networks with buses and cars sharing the same road infrastructure and identify how this performance is influenced by the interactions between modes and the effect of bus stops. Based on simulation data, we develop a three-dimensional vehicle MFD (3D-vMFD) relating the accumulation of cars and buses, and the total circulating vehicle flow in the network. This relation experiences low scatter and can be approximated by an exponential-family function. We also propose a parsimonious model to estimate a three-dimensional passenger MFD (3D-pMFD), which provides a different perspective of the flow characteristics in bi-modal networks, by considering that buses carry more passengers. We also show that a constant Bus–Car Unit (BCU) equivalent value cannot describe the influence of buses in the system as congestion develops. We then integrate a partitioning algorithm to cluster the network into a small number of regions with similar mode composition and level of congestion. Our results show that partitioning unveils important traffic properties of flow heterogeneity in the studied network. Interactions between buses and cars are different in the partitioned regions due to higher density of buses. Building on these results, various traffic management strategies in bi-modal multi-region urban networks can then be integrated, such as redistribution of urban space among different modes, perimeter signal control with preferential treatment of buses and bus priority.

The full paper can be found here.

Assessing Airport Carbon Emissions

Descending through the LA smog

Much of the research about carbon emissions and transportation is focused on highways. A new article from the Journal of Air Transport Management proposes a model to examine carbon emissions and airports. Maria Nadia Postorino and Luca Mantecchini authors of "A transport carbon footprint methodology to assess airport carbon emissions," write:

Airports are important nodes in the air transport system, but also local sources of environmental impacts. Emissions of CO2 are among the most relevant ones because of their potential greenhouse effects. Many policies and guidelines have been identified at national and world level to reduce such kind of impacts. In this paper, a Transport Carbon Footprint methodology has been set to identify Unit Carbon Footprints (UCFs) linked to some identified emission macro-sources – i.e., land vehicles, on-ground aircraft, airport handling and terminal equipment – to compute the contribution of the single macro-source to the total amount of CO2. Particularly, UCFs due to transport activities have been defined according to some relevant transport variables. The computation of UCF values for a given airport allows computing both the contribution of each macro-source and also evaluating the effectiveness of transport-related actions aiming at reducing the carbon impact. The methodology has been applied to the airport of Bologna, in Northern Italy, and its UCF values for the identified macro-sources have been computed.

The full article can be found here

 

Travel Demand Forecasting: Beyond the models and into reality?

Chicago road network

Recently the State Smart Transportation Inivitiative (SSTI) asked if travel demand forecasts from U.S. DOT were accurate

Their answer is no

In the post, "U.S. DOT highway travel demand estimates continue to overshoot reality", Eric Sundquist examines the projections in FHWA's 2013 Conditions & Performance report. He finds that the estimates for VMT growth were 5-6% higher than reality. Concluding:

Had the report based estimates on more current historic data—e.g., VMT trends for 2003-13, which grew at one-fifth the USDOT’s 1995-2010 estimate—the cost estimates would have dropped by tens of billions more, reducing pressure on budgets while freeing up funds to bring the existing system to a state of good repair.

The accuracy of travel demand models and forecast predictions is not a new issue and more people are questioning the methodoloy. This year's TRB Annual Meeting featured a workshop on the issue The Next 50 Years in Travel Analysis: What We Don’t Know but Need to Know. The moderator, David T. Hartgen, mentioned a recent paper he wrote, "Hubris or humility? Accuracy issues for the next 50 years of travel demand modeling," in Transportation. Hartgen, examining 50 years of forecasting, describes problems with accuracy and ways to imrpove models. Definitely a paper worth reading. 

Everybody's a Tourist? Rethinking the Driver Population Factor

objects in mirror

A new paper, "Rethinking the Driver Population Factor," from ITS Berkeley's own Joshua Seeherman and Professor Alexander Skabardonis takes a look at the driver population factor currently used in the Highway Capacity Manual

Freeway analysis procedures in the widely used Highway Capacity Manual (HCM) include the input of a driver population factor (Fp), which allows the analyst to adjust the demand depending on the familiarity of drivers with the roadway. This adjustment is based on the assumption that unfamiliar drivers will drive at slower speeds with longer headways and that higher capacity would therefore be required. However, little research supports the use of the Fp, and the HCM cautions against the use of Fp unless the analyst is fairly certain the traffic stream is actually unfamiliar with the roadway. As an experiment, three bottlenecks in California were selected and analyzed during the weekday peaks and weekend afternoons in periods during which the traffic stream was likely to be nonlocal. The results showed that the changes in flow were minor at all three locations. Further research with additional sites and an increased awareness of the definition of familiarity will be required to confirm the results from this research.

The full paper can be found online in Transportation Research Record no. 2395 or you can look at the hard copy in the library. 

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