Institute of Transportation Studies Friday Seminar: Lessons Learned from Spatiotemporal Studies of Freeway Carpool Lanes


Late August means the end of summer is nigh, students are back, classes are in session, and it's the return of the Friday Transportation Seminars. This semester there are some changes to the seminars - Cookie Hour and the seminar will take place in the same location in 290 Hearst Memorial Mining Buidling. We also encourage you to follow along (and participate) with the Twitter hashtag #itsberksem

This week's Friday Seminar features ITS's own Professor Michael Cassidy presenting, "Lessons Learned from Spatiotemporal Studies of Freeway Carpool Lanes."

The presentation explores how the segregation of distinct vehicle classes on a roadway can improve travel conditions for all of the classes. Insights come using freeway carpool lanes as case studies. Spatiotemporal study of real sites shows (i) how the activation of a continuous-access carpool lane triggers reductions in vehicle lane-changing maneuvers, and (ii) how the reduced lane-changing can “smooth” and increase bottleneck discharge flows in a freeway’s regular lanes. Theoretical analysis predicts that, thanks to this smoothing effect, even underused carpool lanes can diminish both the people-hours and the vehicle-hours traveled on a freeway. Relevance to bus lanes is briefly discussed. Further insights come via critiques of certain practices that degrade the effectiveness of carpool lanes. Spatiotemporal traffic data reveal that a policy aimed at improving carpool-lane speeds has backfired, owing to a friction effect. The policy mandates the eviction of select fuel-efficient hybrid vehicles from carpool lanes. These evictions have caused queues to expand in regular lanes during the rush. And these expanded queues, in turn, slow vehicles in the adjacent carpool lanes. Spatiotemporal data further show that efforts to combat the friction effect by deploying limited-access carpool lanes can also backfire, because the designs for these lanes are prone to creating bottlenecks.

The Friday Seminar takes place on August 29, 2014 from 4:00-5:00 PM in 290 Hearst Memorial Mining Building. Cookie Hour immediately precedes it at 3:30 PM in the same location. (Note: Cookie Hour is not in the library!) There will be a no-host Happy Hour at LaVal's at 5:00 PM.

SB-743, CEQA, and moving away from LOS

Saturday in LA

Yesterday the Governor's Office of Planning and Research (OPR) released Updating Transportation Impacts Analysis in the CEQA Guidelines. It's the draft discussion SB-743 Environmental Quality: transit oriented infill projects, judicial review streamlining for environmental leadership development projects, and entertainment and sports center in the City of Sacramento. As the bill's name hints, the impetus for the legislation is the contentious proposed new arena for the Kings in downtown Sacramento though the effects will be felt statewide. 

Many of the concerns and questions raised by SB-743 lie in the proposed changes to litigation windows to CEQA (California Environmental Quality Act). The proposed reforms could make it easier for projects to obtain exemptions from the full CEQA project, potentially making the development of previously contested projects easier. 

From a transportation standpoint, the biggest change to CEQA is the use of level of service (LOS) in evaluating the impact of projects. Instead of relying solely on LOS to determine the significance of transportation impacts, OPR proposes:

In developing the criteria, the office shall recommend potential metrics to measure transportation impacts that may include, but are not limited to, vehicle miles traveled, vehicle miles traveled per capita, automobile trip generation rates, or automobile trips generated.

Engineering groups like Western ITE suggested using vehicle miles traveled (VMT) instead of LOS to measure impact as it focuses only on automobile congestion at the expense of other modes. So now that it looks like we're moving away from LOS, what comes next? Researchers have already begun looking at how this will affect models and traffic studies. Fehr & Peers have developed an concise website describing the impacts of SB-743

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!

Transport Infrastructure and the World Cup

III Congresso SIBRT

Last week the 2014 FIFA World Cup kicked off in Brazil. Mega sporting events, like the World Cup and the Olympics, often require mega infrastructure projects for the hosts. For this World Cup, preparations include building five new stadiums, including the much talked about Arena Amazônia in Manaus which almost wasn't ready for the first match, and several transport projects. Airports were considered a headache early in planning, and lots of money and time has been invested in airport upgrades for an already overtaxed civil air system. On the other side, several planned public transport projects, such as monorails in Sao Paulo and Manaus, were cancelled because they could not be delivered in time for the tournament. One of the few public transport projects that succeeded was Belo Horizonte's MOVE BRT, which launched in March 2014. 

Some researchers have called these projects a "missed opportunity" to improve urban mobility in Brazil. Others have focused on how these projects could have reduced transport greenhouse gas emissions if only they were built. (Some of them were quite sustainable.)

For a good roundup of World Cup transport projects winner and losers, NextCity provides a good overview

New NCHRP Synthesis: Response to Extreme Weather Impacts on Transportation Systems

345/365 Flood

This week a new NCHRP Synthesis was published by TRB that covers the effects of extreme weather incidents, such as Hurricane Sandy, on transportation systems. NCHRP Synthesis Report 454: Response to Extreme Weather Impacts on Transportation Systems provides background on the issue and the current state of the practice. The full report can be read here

Google Unveils Self-Driving Car Protoypes

Yesterday Google posted posted information and videos about their purpose-built autonomous car prototpyes they've built and are testing. Google will have 100 of these vehicles built for initial closed-road testing and hope to have them on California streets by the end of 2014. One of the most talked about features is the distinct lack of a steering wheel. And while the future is almost here, it's a good time to reflect on the potential positives and negatives of autuonomous vehicles (according to Vox)

Friday Seminar: Quantifying the Impact of Flight Predictability on Strategic and Operational Airline Decisions

THA A340-500 taxiing for spot.

Tomorrow is the last day of the semester - well done, students! You made it to the end! It's also the last Friday Seminar for the school year. Wrapping things up in style, Berkeley Ph.D. candidate Lu Hao will present her research, "Quantifying the Impact of Flight Predictability on Strategic and Operational Airline Decisions."

The idea of predictability or (inversely) variability is not new in the field of ground transportation, where (un)predictability mainly refers to the unpredictable variations in travel time and is thus directly related to uncertainty of travel time. In the realm of commercial air transportation, there is limited knowledge of how to quantify predictability and assess the potential benefit of improved predictability. Moreover, different aspects in airline decision making require different considerations when trying to measure and assess flight predictability.

In this work, the concept and metric for flight predictability is developed for both strategic and operational airline decision making. For both aspects, the appropriate measure for predictability is defined and the behavioral relationship between predictability and decision making is revealed. The potential benefits from improved predictability are then assessed for the two aspects, using airport departure queue assignment optimization and benefit pool analysis. The saving from improved predictability is significant for both cases, if the right metric is used. Comparing the two aspects, the difference in measuring flight predictability is rooted in the different perspectives of airlines’ consideration.

The Seminar takes place in 212 O'Brien (note the different location!) from 4-5 PM on May 16, 2014. There will be no cookie hour. 

Friday Seminar: The Impact of Adverse Weather on Freeway Bottleneck Performance

Raindrops keep falling on my screen...

It's almost the end of the semester, but we still have two more Friday Seminars! This week is the penultimate seminar featuring Ph.D. candidate Joshua Seeherman. He'll be presenting his research, "The Impact of Adverse Weather on Freeway Bottleneck Performance."

Daily commutes in and out of major cities by automobile will likely encounter multiple locations of delay known as bottlenecks where demand exceeds capacity. It has been long perceived that the performance of these bottlenecks decrease when they are affected by adverse weather such as rain, snow, or fog. This project utilizes existing methodology to measure the discharge rate for four freeway bottlenecks in Orange County, California during both clear and adverse conditions. After confirming that the results agree with past literature, a new model will be proposed attributing different periods of bottleneck congestion during either wet, windy, or foggy conditions to specific weather characteristics. Generic results that can be applied to multiple sites will be shown which will validate the new proposal and hopefully provide guidance for other locations where wet weather is a significant source of delay.

The seminar will take place today, Friday May 9, 2014 from 4:00-5:00 PM in 212 O'Brien. (Note the room change!) Cookie Hour is on this week as well, at 3:30 in the library. 

Friday Seminar: Incorporating Predictability into Cost Optimization for Ground Delay Programs


The Spring semester may be winding up, but we still have Friday Seminars! This week features UC Berkeley Ph.D. candidate Yi Liu presenting, "Incorporating Predictability into Cost Optimization for Ground Delay Programs."

When there is foreseen congestion at an airport, Ground Delay Programs (GDPs) are often implemented to balance arrival demand with available arrival capacity by holding inbound flights at their departure airports. Through this, GDPs transfer expensive airborne delay in the terminal airspace of the arrival airport to cheaper and safer ground delay at the departure airports. In the implementation of GDPs, emphasis has mainly been put on maximizing throughput while predictability is overlooked. As a result, planned and unplanned delays are assigned the same cost coefficient in the GDP cost optimization problem. This ignores the fact that unplanned delays require extra effort from both the flight operator side and the traffic manager side and cause more pain for the passengers, which should correspond to higher costs.

This work introduces the goal of predictability into GDP cost optimization under capacity uncertainty. This is accomplished by assigning extra premiums to unplanned delays and planned but un-incurred delay, due to their unpredictability. To estimate delay components in the cost functions, two stochastic GDP models are developed using continuous approximation and deterministic queueing theory: a static no-revision model and a dynamic model considering one GDP revision. The results from the case study show that unpredictability can have a strong impact on GDP decisions. Depending on the value of predictability, the proposed method may reduce system-wide cost by 10%.

The seminar takes place this Friday, May 2, 2014 in 534 Davis from 4-5 PM. Cookie Hour will commence at 3:30 in the library. See you there!

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