Posts Tagged ‘greenhouse gas’

Personal Rapid Transit (PRT) Papers and Presentations at TRB 2010

Wednesday, February 17th, 2010

There were four personal rapid transit (PRT) –related papers and/or presentations at the 89th Annual meeting of the transportation Research Board (TRB) this year.

Martin Lowson, President of Advanced Transport Systems Ltd., (the developers of the ULTra PRT system) delivered an interesting presentation titled Preparing for PRT Operations at Heathrow Airport, United Kingdom. He showed a BBC video (not available in the US) where the reporter claimed to be the first member of the public to ride the system. ATS is still confident they can build complete systems for $10M to $15M per one-way mile.

Heathrow PRT Maintenance Facility

Heathrow PRT Maintenance Facility

Professor Lowson said that BAA considered PRT to be the only practical solution to their many surface transportation problems. In addition to financial benefits, PRT offers a higher level of passenger service, environmental benefits and a more efficient use of space. He indicated they are well into phase Phase 3 of the following testing and implementation progress chart. ATS Progress

ATS has developed 429 system documents defining: Operations procedures (162), Safety Management System (75), Internal Management (74), Training modules (118). Professor Lowson showed the following slide depicting their safety verification process.

ATS has been surprised to find that passengers expect to share rides and want to wait for others to join them. The ULTra PRT system at Heathrow is in the final stage of test and commissioning and is on target for full passenger operations in mid 2010.

Steve Raney of Cities 21.org presented a paper titled Efficient Edge Cities of the Future and uniquely written in storey form that begins as follows: “October 5, 2020. Hello, my name is Emma Raney. Compared to typical suburban living, I live a life with lower cost of living; more free time; better work/life balance; stronger, more supportive, and more diverse local community; and one-quarter of the energy consumption. My community (SRP) produces emissions well below Kyoto protocol standards.”

The storey continues to describe life in a community that goes to considerable lengths to promote sustainability. Needless to say, the PRT system (a shuttle bus on steroids) is a key part of the community. However it is very much integrated into numerous other forms of accessibility.

Comprehensive Integrated Mobility

Comprehensive Integrated Mobility

“SRP has a personal rapid transit (PRT) system, and I take that to many destinations… I carpool to church… SRP’s PRT connects to PRT systems in other large Silicon Valley office parks (there are 10 others). Via this connection, I connect to a larger variety of stores… Very rarely, I get a little carried away and I end up with a bunch of large items to schlep home. Large wheeled carts are available at some stores. I wheel the cart and items onto PRT vehicle, take my items home, then I wheel the empty cart onto another PRT vehicle where it is re-deployed… I take commuter rail to see Sharks hockey…When I go to Stanford for an event, I usually PRT with bike (on occasion I combine PRT with a foldable electric scooter). To get to places, I walk significantly more than a typical suburbanite – I generally travel the first and last trip segment on foot.”

Robert Baertsch, Nasa Ames Research Center presented a paper titled Renewable Energy Utilization Advantages of Maglev-Based Personal Rapid Transit. “This paper examines the advantages that Personal Rapid Transit (PRT) exhibits in the utilization of renewable energy from usage, distribution, and generation perspectives. The paper also looks at different types of PRT and how they impact the load on the electrical grid. Recent advances in power electronics and maglev technology allow for the design of a novel MPRT system characterized not only by exceptionally low power requirements, but also by a unique capacity to incorporate energy distribution and storage infrastructure into the greater transportation architecture.

MPRT prototype at NASA Ames, Moffett Field, CA

MPRT prototype at NASA Ames, Moffett Field, CA

A hypothetical hybrid MPRT design incorporating energy storage and transmission capabilities is presented. Additionally, thorough carbon dioxide and cost analyses are undertaken in order to more fully understand the wide spectrum of benefits of an MPRT solution in comparison to Conventional Vehicle (CV) and Plug-in Hybrid Electric Vehicle (PHEV) approaches. We conclude that an MPRT system not only offers significant advantages over other technologies in efficiently utilizing renewable energy, but, moreover, that the unique potential of this concept to incorporate power transmission, storage, and generation infrastructure makes it ideal for addressing the energy challenges of the near and distant future.”

The system is anticipated to operate at 40 mph in downtown areas and at highway speeds elsewhere. The upper speed limit is 150 mph. Linear induction motors are built into the guideway. An equivalent 325 mpg and capital costs under $10M per one way mile (up to $18M including integrated photovoltaic panels and power distribution) are anticipated.

John Lees_Miller, University of Bristol, United Kingdom presented a paper titled Theoretical Maximum Capacity as a Benchmark for Empty Vehicle Redistribution in Personal Rapid Transit. “A Personal Rapid Transit (PRT) system uses compact, computer-guided vehicles running on dedicated guideways to carry individuals or small groups directly between pairs of stations.  Vehicles move on demand when a passenger requests service at his/her origin station. Because the number of trips requested from a station need not equal the number of trips ending there, some vehicles must run empty to balance the flows. The empty vehicle redistribution (EVR) problem is to decide which empty vehicles to move, and when and where to move them; an EVR algorithm makes these decisions in real time, as passengers arrive and request service.

This paper describes a method for finding the theoretical maximum demand (with a given spatial distribution) that a given system could serve with any EVR algorithm, which provides a benchmark against which particular EVR algorithms can be compared.  The maximum passenger demand that a particular EVR algorithm can serve can be determined by simulation and then compared to the benchmark. The method is applied to two simple EVR heuristics on two example systems, and the results suggest that this is a useful method for determining the strengths and weaknesses of a variety of EVR heuristics across a range of networks, passenger demands and fleet sizes.

This paper demonstrates a new method for the evaluation of empty vehicle redistribution (EVR) algorithms, providing an absolute measure of their performance according to a metric based on the capacity region for a given network. The capacity region is defined as the set of OD matrices which are feasible in the sense that their demands can be met without passenger queues growing indefinitely.  It describes the maximum possible demand that a particular system could serve with an ideal EVR algorithm, and hence acts as an absolute benchmark against which different EVR algorithms can be compared.

The ability to compare and evaluate EVR algorithms is important for the successful operation of highly-connected PRT systems…  In normal PRT operation, the minimization of passenger waiting time is usually the priority, and hence one could expect an EVR heuristic which prioritizes this…to be in operation.  At times of high demand, however, when the vehicle fleet is stretched and there are passengers waiting at numerous stations across the network [this]… often moves vehicles too far.  One would instead prefer an algorithm which prioritizes the efficient use of the vehicle fleet…

This analysis also shows how both the network topology and the spatial distribution of the demand can affect EVR performance, even when line congestion is ignored…The proposed method allows for the absolute assessment of EVR algorithms in terms of throughput, subject to the modeling assumptions…There are a number of alternative heuristics already present in the literature … and an analysis of these algorithms using this evaluation tool is a natural next step.”

Transportation is Broken – a New Solution is Needed

Tuesday, September 15th, 2009

Transportation is Broken – a New Solution is Needed

A review of the major characteristics of our urban transportation system quickly reveals that it is thoroughly broken. Of even greater concern is the fact that most of the solutions currently gaining traction will do little to solve the most pressing problems.

The problem

Let’s start by comparing how various indicators have grown relative to population growth over the past 20 years. Table 1 lists major transportation characteristics and their growth over a 20 year period. The horizontal red line shows the U.S. population growth over that time (about 24%), and the discussion below compares the growth of each characteristic to the population growth, in order to put things in perspective (if nothing changed, these characteristics could all be expected to grow at the same rate as the population has grown).

1990-2010-skewed

Accidents. The total number of accidents has actually declined. While this is the only factor to decline, and clearly a good thing, it is still not nearly enough. Over 40,000 people are still killed on US roads annually (compared with total U.S. deaths in Vietnam – 58,159; Iraq – 4,334; 9/11 – 2,993), and road traffic injuries are one of the top three causes of death for people aged between 5 and 44 years worldwide. Lest you think the US is much safer than the rest of the world, we are not. There are approximately 60 countries with lower death rates per 100,000 population. Improving safety is no easy feat, since advances in safety technology can be easily offset by societal changes, such as texting while driving.

Use of Public Transportation. Transit use grew a little more than population but much less than passenger vehicle miles traveled. Try as we might, we just cannot convince people to leave their cars for transit. During the recent period of high gasoline prices, a small jump in transit use was experienced. This caused problems for transit agencies around the country, because they lose money on each rider! This unsustainable practice was exacerbated by reduced tax-based subsidies and meant that many agencies had to reduce service at the precise time they should have been increasing it. Subsidized transit systems may be necessary to ensure that the disadvantaged have reasonably priced transportation. However, a sustainable transit system, that can rise to meet changing demand, needs to cover at least its operating expenses from the fare box – something that few US transit systems can accomplish.

Transportation Energy Use. This is growing an alarming 50% faster than the population and a large portion of this energy comes from foreign oil suppliers. 96.6% of all transportation energy use is petroleum-based and any growth at all is problematic. As cheap oil resources are depleted, and as countries such as India and China dramatically increase their oil use, cost of oil is likely to rise steeply and cause serious problems for transportation.

Delays Caused by Congestion. As more and more cities face rush-hour gridlock (and rush-hours get longer and longer), this factor is growing twice as fast as the population and congestion now wastes 3.5 billion man-hours every year. We do not seem to be able to build ourselves out of this problem. Consider I-25 through Denver; Two years after a major improvement project took it from six to eight lanes plus light rail, it regularly suffers congestion similar to what it did before the construction. Paradoxically, even in bad traffic, the light rail train seldom passes the automobiles. This is because the light rail system only averages under 25 mph. By the way, the light rail’s two lines cost about the same to build as the eight lanes of highway, even though they carry much less traffic.

Passenger Vehicle Miles Travelled. The amount of driving we do is outgrowing the population by almost three times! This high level of passenger vehicle use is widely seen as being unsustainable. The energy used (and the related foreign oil dependence) is seen by many as being the major issue. However, automobile use brings numerous other problems. While accidents and congestion are discussed separately, two other problems are real estate/infrastructure and automobile manufacture. Each car typically requires four parking spaces (one at home, one at work and two others for intermittent use). The cost of this infrastructure (these spaces are typically paved and often roofed) and the street/road/highway infrastructure, needed to support our automobile use, is enormous. At the same time, the real estate used to support automobiles increases the cost of other utilities and decreases the quality of urban living. Furthermore, the cost of highways is increasing as design standards are continually raised in an attempt to reduce accidents. In addition, the tax revenue to support this infrastructure has not kept pace with the need, and we are likely to face increased taxes and/or more and more tolled highways. The cost to society of individual automobile ownership is rising as we strive to make cars more sustainable. It’s time we took a long hard look at what automobile ownership really costs.

Logistics Costs. These are the costs of moving goods and they have increased far faster than the population has grown. At this pace, logistics costs are set to have major impacts on our economy. Part of the reason is that we move a very large proportion of goods by semi trucks rather than rail. Rail is a far more efficient way to move goods, but we lack the infrastructure to economically collect and distribute goods at the ends of the rail lines. Shipping suffered from a similar problem, wherein the cost of handling goods in harbors exceeded the cost of shipping them over the seas. This changed with the advent of container ships. A similar revolution is needed for rail.

Greenhouse Gas Emissions. Transportation accounted for 47% of the net increase in total U.S. greenhouse gas emissions since 1990. It currently contributes 34% of all greenhouse gas emissions. Reducing transportation-related greenhouse gases requires reducing the amount of energy used by transportation, as well as changing the primary source of that energy.

A solution

Think transit is the solution? Think again. In the U.S., transit uses (wastes) as much energy per passenger mile as the automobile. This is largely because trains and buses run around empty most of the day. Transit infrastructure is expensive to build, consumes much real estate and resources, and its construction contributes significantly to greenhouse gases. High speed rail and air travel may be good solutions for long distances, but both suffer a last mile (or last many mile) problem and do nothing for urban mobility.

It is amazing to think that we are still using the stagecoach model for transit. A stagecoach runs on fixed routes with designated stops. There is seldom a stop at the desired origin and destination (the first/last mile problem mentioned above). The vehicle accommodates many people, to spread the cost of the driver, and has to stop whenever somebody needs to get on or off. All we have done to this model is make the vehicles bigger, turn the stops into stations and the routes into corridors. The ride may be a little smoother and the speed a little higher, but the quality of service has hardly improved. A rail system, with top speeds in the fifties and stations every mile, has an average speed under 25mph. “Modern” street cars often have average speeds in the single digits. It is no wonder transit only achieves a mode share of around 4%. The model is broken and we need to quit trying to fix it. We need a new model.

What if you did not have to wait for transit, you always got a seat, and it took you where you want to go without stopping? Would you use it? The only mode of transportation that currently operates this way is the automobile at 3a.m. Even then, stops at “dumb” traffic signals for no crossing traffic at all are often required. Amazingly enough, transit that operates this way was invented over fifty years ago. It is called personal rapid transit (PRT) and it can be likened to automated (driverless) taxis operating on a system of guideways. The reasons PRT could help solve our transportation problems are:

1. It has a high level of service (more like a car than a bus) and really can attract drivers from their cars.

  1. It uses about a third the energy of most other modes.
  2. It is electrically powered so, as we convert the grid to renewable sources of energy, we automatically also convert PRT-based transportation.
  3. It has proven to be about a hundred times safer than conventional transit.
  4. Elevated or buried (PRT tunnels are much smaller to move the same number of people) guideways do not use up real estate or cause neighborhood severance.
  5. Small vehicle sizes (like a small automobile) require minimal infrastructure.
  6. Each automated T-Pod (transportation pod) will be reused fifty or more times a day – an efficient use of manufacturing resources and a reduced need for parking.
  7. In off-peak times, unused T-Pods wait in stations or depots – there is much reduced empty vehicle movement.

Table 2 below shows my opinion of the extent to which various solutions are likely to have a positive impact on the transportation problems mentioned at the beginning of this discussion. 0 = no impact, 1 = some impact, 2 = significant impact. Certainly, some will argue with my ratings, which are based on my own opinions and analyses. In addition, PRT has yet to be proven in large applications. The point is that PRT appears to have the potential for quite significant impacts across the board, yet it is receiving attention that is dramatically disproportionate to this potential.

comparison-chart

References:

US DOT Bureau of Transportation Statistics

World Health Organization

US DOT Bureau of Transportation Statistics

US Department of Energy

American Council for an Energy-Efficient Economy

Steiner, C., $20 Per Gallon

2009 Urban Mobility Report

Federal Highway Administration

Federal Highway Administration

U.S. Environmental Protection Agency

U.S. Department of Transportation

Muller, P.J., Personal Rapid Transit Safety and Security on a University Campus