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New lightweight subway train from Siemens

The Inspiro lightweight subway train from Siemens is based on a lightweight design with aluminum profiles. The six-car train weights around six tons—some 3% lighter than a comparable unit. The trains also use less energy and can transport more passengers.

Transit companies have the option of equipping the trains with additional energy-saving systems, such as those that control air conditioners with carbon-dioxide sensors or utilize energy-efficient LED lighting systems. The Inspiro can be almost fully recycled after its roughly 40-year service life. The metro operating company in Warsaw will begin taking delivery of the first 35 Inspiro trains in the fall of 2012.

Numerous measures were undertaken to reduce the weight of the Inspiro. The front end of the cars alone, which houses the couplings, weighs 500 kilograms less than before.

To identify areas in which fewer materials could be used without limiting functionality, the entire car body was computer analyzed by means of the finite element method. Certain components in the cars themselves were made as multifunctional as possible—for example, parts of the ceiling also serve as cable ducts. In a further effort to reduce weight, air ducts are made of light textiles rather than the metal previously used, while a new type of cork-aluminum floor weighs 30% less than before, acts as a noise dampener, and also provides better heat insulation.

Measures taken into account as early as the design phase form the basis for the train’s extremely high recycling rate of 95%, which Siemens Mobility has already demonstrated in the Oslo subway.

The trains can consist of between three and eight cars and be equipped with different motors. In addition, the length, width, and height of the cars can be varied in line with existing infrastructure like tunnels and subway platforms. The Inspiro concept, which also reduces development times and costs, is part of Siemens’ Environmental Portfolio, with which the company generated about €30 billion (US$39 billion) in sales in 2011.



Wow, all that effort to get just a 3% weight saving?

I guess the 90/10 theory applies here: "You get 90% of the benefits out of 10% of the effort. To get the extra 10% benefit, it takes 90% more effort."


I'd say it is a mistake and they meant 30%


3% is mentioned in the Siemens link as well - if it's a mistake, it's a big mistake...but the 95% recycling rate is impressive.


You are right, they mention a 30% lighter floor, but 3% over all.


So the linked article says they saved 6 tonnes per 6 car train, or one tonne per car (500 kg in each front coupling alone).

If that really was only a 3% weight saving then each car would normally weigh 33 tonnes - sounds a bit too much for me!


I checked the German version and it says 3%, so I must be wrong.
I think the English translation emphasizes the lightness, while the German one (and the Siemens brochure) does not.

A 3% lightening of a subway car doesn't sound like very much, and not a headline (in my opinion), but I suppose it is better than nothing.

I heard that subways and trains are way over engineered, so that might explain the 33 tons / car, but it does seem very heavy.
[ I just found a link to the New York subway cars which weigh 38 tons, so we are in the ballpark ]


Subway cars can transport between 200 and 300 passengers and weight between 25 tonnes and 40 tonnes. Many of the lightest (all aluminium 25 tonnes to 27 tonnes units) were built for the Toronto system between 1962 and 1976. The H-4 series (26.6 tonnes) could carry 305 passengers or about 11 passengers/tonne. Those very light aluminium cars are being replaced with heavier 34 tonnes Rocket stainless steel units. Other cities, like Bordeaux, use much small 8-tonnes cars but are limited to about 6.5 passengers/tonne. New composites cars could weight as little as 20 tonnes but would cost a bit more.

Service life of aluminium or stainless steel units is about 40 years.


Things made of aluminium are not all that much lighter than things made of steel. Yes, sure the metal is lighter of a given tensile strength but its fatigue resistance is lower so if you want something made of aluminium to last you have to make its parts about 3X thicker.


ai_win...if that was true, all large passenger airplanes would be made of heavier stainless steel. By the way, there are still a few re-engined pre-1935 aluminium DC-3 flying. Not bad for aluminium fatigue resistance?


Fatigue limit, endurance limit, and fatigue strength are all expressions used to describe a property of materials: the amplitude (or range) of cyclic stress that can be applied to the material without causing fatigue failure.[1] Ferrous alloys and titanium alloys [2] have a distinct limit, an amplitude below which there appears to be no number of cycles that will cause failure. Other structural metals such as aluminium and copper, do not have a distinct limit and will eventually fail even from small stress amplitudes.


A friend of mine is a mountian biker, she pointed me to this;

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