Posts Tagged ‘2getthere’

Personal Rapid Transit and Testosterone

Monday, July 18th, 2011

I have recently spent quite a bit of time meeting with and/or discussing PRT with different early-stage suppliers. The common theme seems to be that there is just too much testosterone in this business! Almost every vendor strongly believes that their solution is by far the best and that all others have fatal or near-fatal flaws. Gentlemen (there are no ladies in this group), it is in your own best interests to be a bit more humble and to not discount your competitors, they are generally smarter than you give them credit for.

Oftentimes when a competitor’s weaknesses are pointed out to me, I am aware that they are working on improvements and/or that these same weaknesses are not as serious as made out and/or are in fact strengths in some situations. I hope that all vendors are aware that marketing one’s strengths is more effective than marketing the competition’s weaknesses.

Those vendors who are in the very early stages should note that it has been many years since I have heard any representative of the three  vendors with commercially-available systems make a derogatory statement about any other! In fact these three vendors cooperate well in their efforts related to the Advanced Transit Association.

The table below attempts to summarize the stage of development that the significant vendors are in. I have no intention of mis-characterizing anyone’s efforts. If I have omitted or incorrectly categorized a company or two, please let me know. An open guideway system is one where the vehicles steer themselves (as opposed to a captive bogey system where the guideway steers the vehicles). Engineering design means more than pretty illustrations on a website. By Test Track I mean an active full-scale track demonstrating switching. A commerical project is one for which the vendor is being paid and is under contract (I realize I am giving ULTra-Fairwood the benefit of the doubt on Amritsar).

PRT Technology Development

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Some Thoughts on Group Rapid Transit

Wednesday, June 29th, 2011

The Morgantown PRT system which has been operating in Morgantown West Virginia since 1975 is actually a group rapid transit system (GRT). GRT systems have larger vehicles and passengers are typically required to share rides with others going to the same destination(s). These vehicles also typically accommodate standees thereby fitting more passengers into a smaller space. As accustomed as we are to large trains and buses, many believe that larger GRT vehicles make more sense than smaller personal rapid transit (PRT) vehicles. But do they?

Morgantown PRT

Morgantown PRT

The answer is not simple. It depends on many factors. Larger vehicles require larger stations and more substantial guideways. Thus, the capital costs can be higher. The operating savings resulting from carrying more passengers in fewer vehicles can be offset by the additional cost of running larger empty vehicles during off-peak periods.

Because of the standees, GRT vehicles cannot accelerate or decelerate as quickly as PRT vehicles can. This requires greater separation (headway, or time between vehicles) in order to meet the same safety criteria. This in turn means that GRT’s capacity gains are less than would be expected by just comparing vehicle capacities.

2getthere GRT

2getthere GRT

GRT cannot match the high level of service of PRT where everyone gets a seat, nobody waits for more than about a minute and trips are nonstop. With GRT, seats are in relatively short supply. Passengers have to wait (typically up to about five minutes) for other passengers to fill the vehicle. In addition each vehicle may make a number of stops along the way.

The requirement for GRT vehicles to wait for passengers to arrive who all share the same destination(s) means that GRT does not function very well when there are numerous stations in a system. Either the wait times get quite long or most vehicles are nowhere near full.

Nonetheless, GRT can carry more passengers per hour along a guideway. Increased guideway capacity can be a useful attribute for a networked PRT system where there is intense demand between a few station pairs, but the majority of the demand can be handled by PRT vehicles. In this scenario, GRT service between the busy station pairs can be integrated with PRT service elsewhere. If the GRT vehicles can run on the PRT track, it could be feasible to intermingle the vehicles, changing the fleet mix to meet demand fluctuations. Vectus is developing a GRT vehicle that will run on their PRT track. Another solution that could achieve a similar result could be to platoon PRT vehicles together (either physically or electronically). Forming and breaking the platoons in stations could eliminate safety issues associated with doing so on the fly.

Personal rapid transit systems may be well advised to develop ride sharing/platooning/GRT options to meet the capacity demands that are bound to arise as applications become larger and more diverse. Some may bemoan the need to sacrifice some of the “personal” aspects but, in many countries, the demand for mass transportation will predominate. The distinction between PRT and GRT may become blurred.

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Personal Rapid Transit Reliability

Thursday, April 7th, 2011

Personal rapid transit (PRT) was originally envisioned as a new mode of urban transit. As such, extreme reliability was not required. It is appropriate to examine PRT’s reliability potential a little more closely now that it is being implemented in airports and under consideration for applications where reliability is very important, if not vital.

Reliability can be defined as the percentage of trips that meet predefined parameters. In a PRT system these parameters could be, for example, 50% of people wait less than one minute and 95% wait less than three minutes. Based on parameters such as these, the 2getthere Masdar PRT system is operating at 99.3% and the ULTra Heathrow PRT system achieved 99.6% during passenger trials. By contrast, the Morgantown PRT system achieves about 98.5%. All of these are considerably higher than transit level of service A which is defined as 97.5%.

Let’s examine what these percentages really mean. 97.5% reliability means that 25 trips out of one thousand (one in 40) do not meet requirements. So, if you have forty work trips a month on a bus system operating at level of service A, you can expect to be late for work, or late home, once a month.

98.5% means 15 trips per thousand do not meet requirements. This is 1.6 times (25/15) more reliable than 97.5%. Similarly 99.6% is 6.25 times (25/4) more reliable than transit level of service A.

PRT system developers can predict reliability by knowing the mean time between failures for critical components. It is good to see that both ULTra and 2getthere are achieving public service reliability values similar to those commonly seen on airport people movers. This implies that their statistical analyses of reliability issues were accurate.

While it is acceptable on most systems for a small percentage of passengers to receive slightly lower than desirable service every day, the question arises as to how often the system will fail completely and how is such failure defined. Let’s define complete failure as the entire system breaking down for 15 minutes and then immediately resuming full service. If the system we are considering has 0.0% reliability of serving essentially all passengers in 0 minutes and 99.5% reliability of serving essentially all passengers in 3 minutes, it is clear that the reliability at 15 minutes will be extremely high. This means that the chances of such a breakdown from known causes of failure will be extremely remote.

Extensive breakdowns are typically caused by unknown causes of failure which, by definition, cannot be statistically estimated. These failures are of two basic types – those that also impact most surrounding systems and those that only impact the system of concern. The latter type is the one that must be protected against. Fortunately it should be extremely rare. Nonetheless, if the PRT system is vital to facility operations, breakdowns must be mitigated.

PRT system breakdown mitigation usually takes the form of avoiding single points of failure and providing multiple backups or redundancies. Examples include alternative guideways or routings that can route passengers around a temporary guideway issue, backup power sources, redundant computer systems, emergency walkways and backup bus systems. Rather than fail completely, a good PRT system should have the ability to provide degraded, but acceptable, service at all times except when the failure is an event that is so significant as to shut down all other transportation systems in the area.

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Masdar Personal Rapid Transit (PRT) Opens

Thursday, December 9th, 2010

On Sunday, November 28th, the Masdar PRT system opened to the public. To quote Larry Fabian, 2getthere, the manufacturer, got there. 2getthere operates the system with the support of Singapore Mass Rapid Transit. Masdar City is a new carbon-free city being developed adjacent to Abu Dhabi in the UAE.

The system has 10 passenger and 3 freight vehicles serving 2 passenger and 3 freight stations connected by approximately one mile of track. The system is in operation 18 hours a day, seven days a week serving the Masdar Institute of Technology. Trips take about 2 and a half minutes and are presently free of charge. Average wait times are expected to be about 30 seconds.

Masdar PRT Station

Masdar PRT Station

Robbert Lohmann, Marketing Director for 2getthere, is quick to point out that the elaborate stations are not necessarily reflective of what a station should look like, but more an indication of what one could look like, if desired.

As mentioned previously, it is unlikely that this system will be extended throughout the entire Masdar City as originally planned. However, it is hoped it will be expanded beyond the extent of the present rather limited system.

The Heathrow ULTra PRT system recently achieved 99.6% availability during four weeks of passenger trials. We look forward to receiving availability results from Masdar. It will bode well for PRT if they are in a similar range. To put 99.6% in perspective, it means 4 trips in a thousand do not go as planned. This is six times more reliable than transit level of service A for transit reliability as defined in TRB’s Transit Cooperative Research Program (TCRP) Report 100: Transit Capacity and Quality of Service Manual, where 25 trips per thousand are permitted to be late.

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Urban Personal Rapid Transit Guideways

Thursday, November 25th, 2010

Communities considering retrofitting personal rapid transit (PRT) guideways in urban settings are finding this is not always easily accomplished. In most situations it is logical for the guideways to be within existing street rights-of-way (ROW) and these are often cluttered/adorned with trees, overhead utility lines, street lights, traffic signals, signs, etc. In addition, the adjoining buildings often have little or no setback and can be significantly impacted by an elevated guideway in close proximity. To help highlight some of the opportunities and hurdles, we have developed a series of illustrations showing different potential guideway locations within an existing urban ROW. They conclude with some ideas for proposed (new) ROWs, highlighting the potential to reduce guideway visual intrusion, while taking advantage of the mobility offered by PRT to also reduce vehicle intrusion. The illustrations can be downloaded here.

The final two sketches are dramatically different than the others and prompt the question: “Shouldn’t this be the ultimate goal of PRT?” Visit this website to learn more about sustainable green cities enabled by PRT.

PRT proponents often promote the concept of using the guideway infrastructure to support streetlights and eliminate the need for overhead utilities. This very logical concept may prove quite difficult to implement in practice. Utility companies presently resist hanging their utilities on each other’s poles – a seemingly equally logical concept.

If common use of the guideway structure is to be accomplished, it will be important that each entity using the structure can obtain unhindered access to their key elements, without hindering the functioning of the key elements of the other entities. Utility lines strung on the guideway structure above a suspended PRT system (such as Beamways, MISTER or SkyTran) may be almost inaccessible, without somehow reaching over the dynamic envelope reserved for moving T-Pods – a maneuver unlikely to pass the safety certification process.

Utilities strung under the guideway of a supported PRT system with the bogie captured within the guideway structure (such as Skyweb Express) might pose similar problems if the guideway covers had to be removed while working in close proximity to the energized utility lines. The best opportunity for PRT and utilities to coexist seems to lie with supported systems of the open guideway type (such as 2getthere, ULTra or Vectus). Such systems could allow almost all PRT maintenance to be accomplished by workers working above the guideway riding surface and almost all utility maintenance to be accomplished by workers working below the guideway riding surface. Thus the riding surface would form a well-defined natural boundary between the systems.

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