Tomorrow's TRANSOC Friday Seminar features Ph.D. candidate Ilgin Guler presenting, "Strategies for Sharing Bottleneck Capacity among Buses and Cars."
Buses that operate in mixed traffic can be impeded by car congestion, leading to unreliable and slow bus service. Conversely, buses that frequently stop to serve passengers can interfere with the movement of cars. To address these issues, exclusive bus lanes have often been used to segregate buses from other traffic. These exclusive bus lanes provide a means for buses to bypass car queues, thereby increasing bus speed and potentially decreasing the total person hours travelled on a network. In urban settings exclusive bus lanes are typically deployed by converting an existing general purpose lane to bus use only. However, in cases where bus flow is low, these lane conversions can increase the queuing and delays to cars. The problem is particularly acute at roadways bottlenecks, since cars now discharge from one less lane, even when the bus lane is unoccupied.
This research examines strategies for judiciously inserting cars between buses in ways that minimize the losses in a bottleneck’s car carrying capacity when bus demand is low. The idea entails sharing lanes among buses and cars in the vicinities of critical bottlenecks; and to have these shared lanes augment exclusive bus lanes that are deployed elsewhere throughout the network. The specific type of sharing strategy to be used near any given bottleneck would depend upon its operating conditions. In all cases the goal is to prioritize bus travel while minimizing the additional delays that this prioritization imparts to cars. Analysis unveils the ranges of bus demands for which the shared‑lane strategies are superior to ordinary lane conversions. We find that the shared-lane strategies have merit in many instances. Implementing these strategies for a real-world case study in Amman, Jordan produces promising outcomes: simulation analysis indicates that the delay savings to cars brought by the lane–sharing strategies are considerable. The proposed ideas can help increase the political acceptability of bus priority systems and promote public transportation in cities of various sizes.
The Seminar will be from 4-5pm in 406 Davis Hall. There will be no cookie hour precedding it this week, so you'll need to sort out your sugar fix some other way.
The U.S. Congress voted today on a new transportation bill. Included in the bill was language that killed funding for Obama's High Speed Rail program. From AP:
The House voted Thursday to kill funds for President Barack Obama's signature high-speed rail program, but the initiative may have some life in it still.
Republican lawmakers are claiming credit for killing the program. But billions of dollars still in the pipeline will ensure work will continue on some projects. And it's still possible money from another transportation grant program can be steered to high-speed trains.
Obama had requested $8 billion in fiscal 2012 for the program and $53 billion over six years.
The study is concerned with the vehicular interactions that arise when carpool and regular vehicles are segregated in their own lanes. Real data show that reserving a lane for carpools on congested freeways induces a smoothing effect that is characterized by significantly higher bottleneck discharge flows (capacities) in adjacent regular-use lanes.Thanks to this smoothing effect, we find in many cases that the carpool lanes – even when underused themselves – can benefit travelers in the regular lanes.Ironically, the regular-use lanes are often damaging to the carpool-lane travelers. We find that the vehicle speeds in a carpool lane are negatively influenced by both growing use of that lane and diminishing vehicle speeds in the adjacent regular-use lane.The findings do not bode well for a new US regulation stipulating that most classes of Low-Emitting Vehicles (LEVs) are to vacate slow-moving carpool lanes.Analysis shows that relegating some or all of these vehicles to regular-use lanes can significantly add to regular-lane congestion; and that despite the reduced use of the carpool lanes this, in turn, can also reduce the speeds of those vehicles that continue to use the carpool lanes.Constructive ways to amend the new regulation are discussed, as are promising strategies to increase the vehicle speeds in carpool lanes by improving the travel conditions in regular lanes.
The seminar will take place from 4-5 pm in 406 Davis on November 18. Please come to TRANSOC's Cookie Hour preceeding the seminar at 3:30 pm in the library.
On November 1, the California High-Speed Rail Authority released its Draft 2012 Business Plan showing a final bill of $98.5 billion, twice the previous estimate. The project timeline also was drastically altered, with completion now targeted for 2033 instead of 2020. With the state mired in fiscal woes and the federal government unlikely to approve more than the previously allocated $3 billion grant, finding the funding for the project will present a huge challenge, and the private sector doesn't appear eager to step forward to fill the gap. Opponents argue that the huge cost increase and the decision to begin with a Fresno-to-Bakersfield section make no financial sense, and at least one state senator plans to introduce legislation to scale back the project.
The effects of bus drivers' reactions to schedules, given the status of the buses they are operating, on service reliability are investigated and quantified analytically and empirically. The hypothesis that drivers may deliberately, as a form of control, lengthen or shorten dwell times at stops or adjust speeds between consecutive stops depending on whether buses are ahead or behind schedule is examined. An analytical relationship is derived, based on which an empirical study is conducted. The relationship describes the progression of reliability from stop to stop as a function of drivers' possible reactions to the schedule in the presence of exogenous factors. Such reactions are explored in an empirical study using a large Automatic Vehicle Location (AVL) data set collected by The Ohio State University's Campus Transit Lab (CTL). The drivers' reactions to the schedule are found to be helpful in improving service reliability. Moreover, the magnitudes of the improvements in reliability, resulting from such reactions, and the deterioration of reliability, due to exogenous factors, are quantified. Given the reliance on CTL data in conducting this study, a brief motivation, history, description, and uses of CTL are discussed as well.
Rabi Mishalani is an associate professor at The Ohio State University with the Department of Civil and Environmental Engineering and Geodetic Science. His areas of interest and expertise include the application of probability modeling and statistical methods to the planning and managing of public transportation and transportation infrastructure systems. He is playing a lead role in developing and directing OSU's Campus Transit Lab (CTL), a "living lab" that supports research, education, and outreach. He also is the co-director of the US DOT Region V University Transportation Center.
The seminar is Friday, November 4, 4-5pm, 406 Davis Hall.
Last week the Arizona DOT filed an application with FHWA to impose a toll on the 29.4 mile stretch of Interstate 15 within Arizona's border, which links Nevada and Utah. Utah Governor Herbert strongly opposes such a move.
"I strongly oppose any plans to levy tolls on Arizona's portion of I-15, or on any portion of I-15," said Governor Herbert. "Every state pays into the Highway Trust Fund, and every state receives money from the Highway Trust Fund to maintain the segments of the Interstate Highway System inside their respective borders. Arizona cannot pick and choose which parts of our national interstate network it wants to maintain. If Arizona has been negligent in its maintenance of I-15, it should not try and foist its responsibility onto highway users or neighboring states who already pay into the system with their own tax dollars."
Walking and bicycling can increase the livability and sustainability of communities, but the automobile remains the dominant mode of transportation in most metropolitan regions in North America. To change travel behavior, a greater understanding of the mode choice decision process, especially for walking and bicycling, is needed.
This presentation will summarize research on factors associated with walking and bicycling for routine travel purposes, such as shopping. Mixed logit models showed that walking was associated with shorter travel distances, higher population densities, more street tree canopy coverage, and greater enjoyment of walking. A limited sample of bicyclists suggested that bicycling was associated with shorter travel distances, more bicycle facilities, more bicycle parking, and greater enjoyment of bicycling. Respondents were more likely to drive when they perceived a high risk of crime, but automobile use was discouraged by higher employment densities, smaller parking lots, and metered on-street parking. Interviews provided the foundation for a five-step theory of how people choose travel modes: awareness and availability, basic safety and security, convenience and cost, and habit.
Abu Dhabi's English language news publication, The National, reports that the three-day BlackBerry service disruption has coincided with a 20% decline in traffic accidents in Dubai and a 40% decline in Abu Dhabi.
"'Absolutely nothing has happened in the past week in terms of killings on the road and we're really glad about that,' Brig Gen Al Harethi said. 'People are slowly starting to realise the dangers of using their phone while driving. The roads became much safer when BlackBerry stopped working.'"