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:
Fleetnet
Network on Wheels
Secure Vehicle Communication
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.
