Trips by mass transit often contain frequent stops, which makes them slow, often slower than travelling by car. They also incur high costs to operators for the energy required to accelerate trains again after the stop and for the amount of rolling stock and staff needed. Furthermore the uneven loads of a train between different pairs of stops along its route increases costs, too, as the capacity of the train needs to be customized for the maximum load section. Eventually, the costs for building stations are increased by having to customize the length of its stopping bays to the maximum train length along the route, even if most passengers don’t board or alight there.
As all these costs are passed on to the passenger by ticket prices, trips by mass transit would not only be faster, but cheaper, too, if the number of intermediate stops could be reduced. On the other hand, as will be seen, different routing patterns often cause higher waiting times due to reduced departure frequency, or requires the passenger to change trains more often. Furthermore, different routing patterns may also require changes to the ROW, like passing lanes at stations or additional stopping bays.
In order to improve transit, one needs to look at different routing patterns. The most widespread concept is that every train stops at every stop along its route. This scheme has the above-mentioned disadvantages. Another concept is the skip-stop service pattern, by which trains skip certain alternating low-utilized stops along the route. The pattern is described here in more detail. It slightly reduces the line capacity on ROWs without passing lane by increasing the minimum headway.
Another service pattern is „zonal operation“, which is particularly suitable for operation between center and periphery. In this pattern all stations along the route are grouped into certain zones, depending on their distance from the center. Routes are then designed to serve a certain zone only, by traveling without stop between the center and the first stop within their zone, and then stopping at every station within their zone. Usually stations located at the border between different zones are assigned to both zones at once in order to allow interchange between different routes, thus allowing to travel between zones without having to connect at the center.
Further routing patterns are possible if trains are capable of splitting and joining during revenue operation. This enables trains to travel one section jointly, thus occupying only one timetable path, which is particularly useful where the capacity of the ROW is limited, and saving costs for staff, too, if trains are operated in human-driven mode, then to split at a certain station and from there onwards to serve different stops or even possibly different lines. If train units are capable of opening a passage way to coupled adjoining units, passengers could also change trains en route instead of at a station.
The perfect transit vehicle runs on rubber tires, driverless on dedicated ROWs made of concrete or human-driven on ordinary roads, mixing with normal road traffic, and will therefore resemble a bus more than a train. However, it will be possible to couple and also decouple several units into a trackless train, even during revenue operation. Since all axles of all vehicles are steerable, a train consisting of several units will still retain the same small turning circle as a single unit and the latter units will follow exactly the traces of the unit in front, thus allowing for narrow lanes even in sharp curves.
Rubber on concrete is superior for passenger traffic compared to steel wheels on rails. Rubber-tired wheels are more lightweight and they dont require heavy bogies, either, because they don’t need rigid axles. For railway vehicles, the sine running requires this. Light weight saves energy particularly when vehicles have to stop frequently on their way, as is the case in transit. While it is true that today braking energy can be recovered, it is not possible to recover even near 100% of it.
Steel wheels on steel rails have the advantage of lower rolling friction. However, this is essential only for slow and heavy traffic over long distances. Over short distances, as between the stops of a transit line, the energy lost to rolling friction is outweighted by the kinetic energy of the vehicle, and for fast traffic, by the energy lost to wind resistance. Therefore steel wheels of steel rails are superior only for slow freight traffic over long distances which is heavy and doesn’t stop often on its route. Another, albeit minimal advantage of steel wheels on steel rails is the possibility to use the rails as return conductor for electric power supply by overhead wire or third rail. Rubber-tired vehicles can be powered electrically, too, but they require a double-pole power supply.
Steel wheels on rails exert a contact pressure per unit area orders of magnitudes higher than rubber tires on concrete. This causes higher maintenance costs for railways. The low adhesion of steel on steel makes railway vehicles unable to ascend very steep slopes. Rubber-tired vehicles can easily ascend steep slopes, even with only few of their axles being powered, and they can accelerate and decelerate slightly faster than railway vehicles. Furthermore, while the braking distance in normal operation is determined by the need of maintaining comfort and safety of the passengers, thus limiting acceleration and deceleration to approximately 1.3 m/s^2, the emergency braking distance is much shorter for rubber-tired vehicles. When coupling trains within revenue operation, this allows for the vehicle behind to approach the standing vehicle much swifter without compromising safety as there is always the possibility of braking harder should the approaching vehicle transgress its target speed for a given distance. Furthermore, a shorter emergency braking distance allows for a train following onto an occupied stopping bay to under-run the absolute braking distance for normal operation to the vehicle in front after the latter already departed, thus allowing to cut off another 8 seconds or so from the minimal possible headway through a station without passing lane.
On stations, ideally there should be at least a passing lane beside the stopping lane in order to maximize throughput of the exclusive ROW and in order to allow for trains to skip stops. Of course, the costs of providing a passing lane may be prohibitively expensive for underground sections although it allows for shorter platform areas at low-utilized stations, if these are to be served by short train consists only. At stations where several trains should be able to stop at the same time, stopping bays can be aligned either side by side or, length-wise, one after the other. The self-steering capability of the vehicles and the absence of rails allows vehicles to overtake each other at every location along the route, without requiring switches.
The possibility for coupling and decoupling vehicles within revenue operation allows to customize the capacity of the trains to the demands over different stretches of the route, without falling back to short-turning trips, which has the drawback of both reducing frequency at short-turned sections and causing uneven loads at the common sections of the route. Furthermore it allows for different routings of units within the same train consists, thus serving several areas at the end of a common line at once with a high frequency, as, for instance, at the end of a common ROW, and even for units to decouple from one train, serving exclusively a low-utilized station on a line and eventually coupling at the succeeding train on the same line, even if there is no passing lane at the low-utilized station. Ideally, after coupling vehicles in normal operation, the passage way between them should be automatically opened to allow for passengers to distribute themselves evenly over the whole length of the train. For this, both ends of each vehicle should be equipped with a roller shutter.
Ideally, the dedicated ROW for transit vehicles is equipped with electric power supply overhead wires or rails, thus allowing for vehicles to be powered electrically. For spur lines on ordinary roads, however, an electric power supply would be too expensive, therefore vehicles should be equipped with an energy storage, too, allowing to travel over short distances without electric power supply overhead wires or rails.
Transit systems running on customized ROWs only have the limitation of being unable to serve all areas without them. Since customized ROWs are expensive, such areas are plenty. By vehicles being able to drive on ordinary roads and mixing with normal street traffic, they can exploit the higher travel speed on dedicated ROWs while still serving areas away from them. In order to allow for driving on ordinary roads mixing with normal street traffic without taking away space for a driver cabin from the interior, the vehicles are equipped with comprehensive camera surveillance at both ends to supervise street traffic, thus allowing for drivers driving them with their visual input being communicated to them from the cameras to monitors in front of them at a remote office. Remote-controlled driving with visual input from cameras can’t be deemed to be any less safe than driving a tramway, since, in case of sudden failure of the cameras or of the communication link, the vehicle can still emergency brake, albeit only within its exact virtual track and therefore being incapable of evading obstacles. But neither can a tramway which drives on rails within street traffic and is still deemed reasonably safe.
location based service auf dem handy.
automatische erkennung des standortes
problem scheint derzeit noch zu sein: zu geringe verbreitung von
gps-empfängern in autos und vor allem: zu hohe tarife für ständige
(mobil)funkverbindung
es gibt auch ein system, mit dem die verkehrsnachrichten digital zusammen
mit dem radio übermittelt werden. damit könnte es evtl. gehen, vielleicht
sind es aber auch zuviele daten
vorteile: fahrtziel, fahrpreis kann übermittelt werden sowie weitere
bedingungen (nichtraucher, mehrere personen, gepäck). außerdem kann zu
kleinen umwegen (abfahrt von der autobahn) animiert werden. und
rechtzeitiges anhalten kein problem mehr (manchmal sind fahrzeuge zu schnell
und sehen anhalter zu spät)
A step in the right direction is that carpooling sites like Mitfahrgelegenheit.de have introduced access to their data base by WAP, making it possible to use one’s cellphone to find a lift. However, offers by drivers must still be entered manually.
„The trottoir roulant rapide was an experimental high speed moving sidewalk in Paris, France, moving at a speed of 9km/h. Users first entered a slower tape, than a faster one, the two have metal rollers in between. It has produced some injuries, and is not handicap compatible. Today it is converted into an ordinary walkway running at a slower speed.“
This was an interesting innovation in transportation. It’s somewhat disconcerting that it failed only because very few users were unable to keep their feet still when being accelerated by the metal rollers to a speed at which it was safe to step on the walkway.
It needs to be assessed if travelling of heavy duty vehicles at high speeds on dedicated roads is safe and by which measures it can be made safe. In the introductory post of this thread I already noted that a Car2Car communication system is necessary in order to rule out the possibility of rear-end collisions. Furthermore, all vehicles on the dedicated high-speed road should be equipped with an automatic lane keeping system in order to rule out vehicles leaving their lanes because of an inattentive driver and thus causing accidents. Such lane keeping systems already exist and are on sale.
Vehicles can also be caused to leave their lane by a tire blowout, by strong cross wind or by losing grip on a slippery road surface. Tire blowouts can be prevented by regularly checking tire profile and pressure in short intervals and meeting high safety margins. Using run-flat tires can further increase safety. Furthermore it must be ensured that no lost parts or other objects lie on the road’s surface because these can also cause a tire failure if the car collides with them. Therefore all vehicles must be tested that they can’t lose parts or that in case they do lose parts, they will immediately detect it and communicate it to the car behind so that it can stop in due time. In order to prevent people from intruding on the highway and possibly place dangerous objects on the road, the road should be fenced on both sides.
A slippery road surface can be caused by ice, snow or rain. Ice and snow rarely or never occur in most parts of the world and a high-speed road can be reasonably excused for failing to provide high-speed capability in these rare cases. The same holds for strong cross wind, which, by the way, can severely disrupt high-speed railway services, too.
Strong rainfall can cause aquaplaning. However, heavy duty vehicles are less affected by it due to their higher contact pressure per unit area. The likelihood of aquaplaning can be further reduced by running only tires with a high profile. It might be useful to build the road’s surface from drain concrete. These measures should be sufficient to deal with moderate rainfall. In case of very strong rainfall the speed would have to be reduced, just as on ordinary roads.
Altogether, by applying all these measures, a high level of satefy can be provided at a reasonable availability of high-speed capability. In very bad weather conditions safety will be provided by drastically reducing the speed, thus severly disrupting services, just like on an ordinary road. But such very bad conditions happen too rarely for justifying building a much more expensive high-speed railway or maglev just because of that, in most applications. High-speed travel on road has a reasonable availability of high-speed capability and still provides a satisfactory service level when the high-speed capability can not be provided. In case of broken down vehicles services are much less disrupted on a road because all following vehicles can go round it, albeit with a slow speed. In comparison, a high-speed rail track would be completely blocked for a long time.
German Autobahnen have no general speed limit for passenger cars and their accident record compares favorably to highways of other countries. Already today, a large part of all high-speed travel in Germany takes place on the Autobahnen, which proves that high speed travel on road is a viable alternative to high-speed rail.
I am now outlining a possible design for a high-speed bus which is supposed to run of dedicated high-speed roads or customized roads only. It doesn’t need to have the same small turning circle as an ordinary bus. I am therefore at liberty to make it wider and longer than a bus for present-day roads. In order to allow for a 3+3-seating arrangement in 2nd class, I want to make it 3.5 m wide. That’s almost as wide as the Transrapid, which is 3.7 m wide, I just think that 3.5 m are enough for a 3+3-seating arrangement.
The bus shall be 25-30 m long, about as long as a European passenger train car. With a part of the capacity being used for 1st class seats, in 2+2-seating arrangement, I estimate the total capacity of the vehicle to be around 120 passengers.
A present-day double-deck coach is 4 m high and has a headroom of 1.68 m in the upper deck aisle and of 1.8 m in the lower deck aisle. By removing the upper deck, increasing the headroom of the lower deck to 1.9 m, and accounting for the now missing floor between the upper and the lower deck, I arrive at a height of about 2.35 m for the whole vehicle.
The cross-section of the bus:
I estimate the gross vehicle weight not to exceed 40 tons. A JR 700 Shinkansen car is about as long and has an empty weight of 40 tons. This bus, however, does not need two bogies made from steel which alone account for about 10 tons of weight.
In order to calculate the fuel efficiency, I compare it with an ordinary bus of today, which is 2.55 m wide, 3.5 m high, weighs 18 tons overall and consumes about 25 litres at a speed of 100 km/h. Its drag coefficient is about 0.5, so I calculate a wind resistance of Fw=0.6*0.5*2.55*3.5*(100/3.6)**2=2066 N. Assuming a rolling resistance coefficient of 0.01, I calculate a rolling resistance of Fr=0.01*9.81*18000=1766 N. The total energy consumed per 100 km is therefore W=(Fw+Fr)*v*1 hour=(2066+1766)*(100/3.6)*1 hour=106 kWh.
For the high-speed bus, which is aerodynamically shaped, flatter and wider, I assume a drag coefficient of 0.35. Then its wind resistance at 200 km/h is Fw=0.6*0.35*3.5*2.35*(200/3.6)**2=5331 N, its rolling resistance Fr=0.01*9.81*40000=3924 N. This bus needs only half an hour for a distance of 100 km, therefore I calculate a total energy consumption per 100 km of W=(Fw+Fr)*v*0.5 hour=(5331+3924)*(200/3.6)*0.5 hour=257 kWh, which should result in a fuel consumption of about 61 litres per 100 km.
Given the higher capacity of the high-speed bus compared to ordinary buses of today, the fuel consumption per passenger is about the same. The effect of the aerodynamic shape, the lower height and the greater length offsets the effect of the higher speed. The overall fuel consumption per passenger for a fully-loaded bus is in the magnitude of 0.5 litres per 100 km, which is very low.
The bus should be equipped with a lane keeping system which would allow the high-speed lanes to be made no wider than just about 4 m in straight sections and a bit wider in curves, depending on their radius.
On a dedicated high-speed road with just a single lane, vehicles could easily run at a speed of 200 km/h in headways of only 15 seconds. They would thus run at distances from each other of more than 800 m. Already 400 m would be more than sufficient for braking in the unlikely event that the vehicle in front stopped dead and blocked the road, therefore there is plenty of buffer space in the „timetable“ for dissolving traffic jams after a potential disruption. With headways of just 15 seconds, there could be 240 buses per hour and direction on the road, thus allowing for a capacity of 28800 passengers per hour and direction which is far more than even the busiest long-distance traffic corridor in the world has.
It should also be noted that the lower top speed of 200 km/h is partly offset by the higher service frequency compared to many high-speed railways in the world. Many of them run trains in intervals of no shorter than 1 or even 2 hours, particularly in off-peak time. An interval of 1 hour causes the passenger an average waiting time of 30 minutes. High-speed trains typically have a capacity of at least four times the proposed capacity of the high-speed bus. Therefore, whereas a high-speed train would run at intervals of 1 hour, a high-speed bus would run at intervals of 15 minutes, thus reducing the average waiting to a mere 7.5 minutes. Running 300 km/h instead of only 200 km/h saves 10 minutes per 100 km distance, therefore on distances of up to 225 km the bus would actually be faster.
High speed railways are expensive to build and expensive to maintain. Maglev is cheap to maintain, but even more expensive to build than high speed railways. Both modes of transportation usually require high government subsidies at least for the construction of right of way, and their ticket prices are high, too. High speed rail is touted as a solution for travel distances in the range of up to 800 km, as an alternative to air travel. While in many real-world applications it succeeds to beat air travel in total journey time because stations are often closer to the exact origins and destinations of the passengers than airports and because less time is wasted for check-in, security, boarding and taxiing, high speed rail often can’t beat air travel on price or only by a very small margin.
On the other hand, buses do easily beat air travel on price, even on quite long distances. This would make them a very innovative mode of transportation if they weren’t so slow on today’s roads. This raises the question, why they are so slow and if they couldn’t be made faster without increasing costs by much. For ground-based high speed transportation railway and maglev shouldn’t be the only technologies to be considered, but self-steering, rubber-tired vehicles on roads should also be looked into and it should be assessed where their technologically feasible top speed is.
On the following video you can watch somebody driving his car for almost 10 minutes at a constant speed of 250 km/h over a German Autobahn. This ride looks both safe and smooth to me. In fact, much of high speed travel in Germany today doesn’t go by air or train, but by car on an Autobahn.
Unlike railway and maglev tracks, roads are cheap, both to build and to maintain. The contact pressure area of rubber tires on the road’s surface is orders of magnitudes lower than for the wheels of a train on rails. Unlike railway trains, rubber-tyred vehicles can easily climb grades of 10% or more without problems. Therefore roads have little need for tunnels, even in mountaineous terrain. Maglev has little need for track maintenance and can climb steep slopes, too, but their track is very expensive to build, because it requires a stationary linear motor for the whole way, together with separate power supply for every block. A road, however, is little more than a flat surface. Road surfaces made of concrete have been proven to be quite endurable even against heavy duty traffic and to require little maintenance.
Roads can be used more flexibly than rail tracks. Apart from collective passenger traffic, to be served by special, aerodynamically shaped high speed buses, there is also a big demand in fast, yet affordable freight traffic, which today, already goes almost exlusively on the road because for most origins and destinations, this is the only way to create a fast, direct transportation link, without any interruptions or transshipping, between them. And last, but certainly not least, individuals can drive with their own affordable, private cars on the roads. Therefore a road, tailor-made for high speed, can easily attract enough traffic to use up its capacity, and by that, ensuring profitability at low tolls. Another advantage of roads, compared to rail, is their very high flexibity in case of disruptions, accidents or failures. Vehicles are self-steering and can therefore go round obstacles, they are self-propelling and therefore unaffected by power line failures. Furthermore they have very short braking distances in case of emergency, which allows for shorter headways between them.
I suggest to build dedicated roads for high speed travel or to upgrade existing roads or lanes on existing roads for high speeds. Their lanes should be built wide and their curves should be superelevated to ensure a smoother and safer ride. Possibly the surface should be made of a draining material like drain concrete in order to make aquaplaning less likely. A high minimum speed should be enforced for all vehicles to use them, and a drip-feed system installed at the beginning of the road, in order to funnel the vehicles at determined headways through till the end of the road, fast. On dedicated high speed roads with only a single lane, all vehicles should be enforced to travel by the same speed in a determined distance from each other in order to maximize safety, travel speed and capacity. All vehicles should be required to be equipped with a Car2Car communication system which is an ad-hoc mobile network between the vehicles on the road, informing each other of their respective positions and speeds, thus preventing rear-end collisions even behind hilltops or in curves, when the vehicle in front is not visible. The very short braking distances of rubber-tired vehicles permits to fall back to driving on sight, should the Car2Car communication system fail. In that case the road could still be used like an ordinary road.
The following links point to sites about research projects about Car2Car communication system:
Collective passenger transport should be served by wide, long, aerodynamically shaped buses with a low center of gravity by reducing their height compared to today’s buses in order to improve handling. The higher the passenger capacity, the better the economics, including fuel efficiency. Dedicated high speed roads and lanes should be customized for use with high speed buses, particularly in width. But even on today’s highways, like the German Autobahn, it would most probably be safe to raise the speed limit for such special high speed buses to 130 km/h, thus creating a faster, yet affordable transportation option.
It has to be noted, though, that present-day tires for heavy duty vehicles are capable of traveling at maximum speeds of 130 km/h only. I am currently in the process of finding out if tires for heavy-duty vehicles with higher maximum speeds can be produced with sufficient riding quality, safety properties and at an acceptable cost per kilometer.
Ich habe keine Lust, alles doppelt zu schreiben, deshalb kopiere ich einen Eintrag aus einem Forum direkt hierher:
Um den Fahrgästen günstigere Fahrpreise anbieten zu können, sollte die Bahn eine dritte Klasse anbieten, in der auf der einen Seite vom Gang 2 Sitze und auf der anderen 3 Sitze nebeneinander angeordnet sind. Außerdem sollte in dieser Klasse der Sitzteiler, d.h. der Abstand zwischen hintereinander angeordneten Sitzen, von heute 920 mm auf das in der Economy-Class im Flugzeug übliche Maß von 762 mm (Ryanair, Easyjet hat sogar nur 737 mm) reduziert werden.
Durch 5 Sitze statt bloß 4 in einer Reihe wird die Sitzplatzkapazität um den Faktor 1,25 erhöht. Durch einen Sitzteiler von 762 mm statt 920 mm um den Faktor 1,2. Zusammengenommen kann die Zahl der Sitzplätze also um 50% gesteigert werden. In einem IC-Wagen, der heute in der 2. Klasse 80 Sitzplätze hat, könnten in der 3. Klasse 120 Sitzplätze eingebaut werden. Entsprechend würden die Kosten sinken und die Fahrpreise könnten für die dritte Klasse im Vergleich zur 2. Klasse erheblich reduziert werden.
Daß so etwas leicht möglich ist, beweisen z.B. die britischen Class 450 Züge, die ebenfalls eine 2+3-Bestuhlung aufweisen, und dies bei einer Breite des Zuges von nur 2,80 m. Der ICE-T ist 2,85 m breit, der ICE 3 2,95 m, der ICE 1 3,07 m. Auf folgendem Foto kann man die Inneneinrichtung der Class 450 sehen:
In Deutschland werden die Züge ja so betrieben, daß in Hauptlastzeiten mehr Fahrgäste im Zug mitfahren dürfen als Sitzplätze vorhanden sind, so daß diese dann im Gang stehen müssen. In anderen Ländern, etwa in Frankreich, herrscht eine Reservierungspflicht. Gleichzeitig wird dort für die Zukunft eine Überlastung der Paris-Sud-Est-Strecke befürchtet. Die Einführung einer dritten Klasse würde die Kapazität der Züge und damit der Strecke erhöhen, so daß auf teure Maßnahmen an der Infrastruktur verzichtet werden könnte.
Indem man die Sitze gegeneinander versetzt anordnet, ist es möglich, den Komfort bei einer 2+3-Bestuhlung wesentlich zu steigern. Denn es ist nicht der fehlende Platz für die Beine, der das Sitzen auf engen Sitzen unbequem macht, sondern der fehlende Platz für die Schultern und die Arme. Das folgende Bild illustiert, wie Sitze gegeneinander versetzt angeordnet werden können, so daß Schultern und Arme problemlos über die Breite der Sitzfläche hinausragen können:
Dadurch, daß die Sitzfläche, wenn der Sitz nicht besetzt ist, automatisch nach oben klappt, können die nicht am Gang liegenden Sitze leicht erreicht werden. Der vor der ersten und hinter der letzen Sitzreihe durch die schräge, gegeneinander versetzte Anordnung der Sitze verlorene Platz könnte für Toiletten, für technische Einrichtungen, für die Garderobe oder für eine Gepäckablage genutzt werden.
Ok, let me see if I can blog – my first entry: I am interested in tires, because I want to know if it is possible to build a tire for a heavy duty vehicle, with a carrying capacity of 3-5 tons, capable of running at 200 km/h over several hours, with a grip not much lower and a rolling resistance not much higher than a usual tire and a reasonable mileage/service performance. I want to design a high-speed bus
When I looked into it, I failed to get an answer yet, but I came across this interesting innovation in tire technology:
At least the problem of a tire failure would be resolved.
