New York subway authorities have decided to act against accumulations of dirt and litter. With the help of two French companies, they have just acquired a high performance vacuum-cleaning train, called the VakTrak. Rubbish not only gave an unsightly appearance to the underground system, it caused no fewer than four thousand fires each year. While these small fires did not affect passenger safety, they disrupted traffic and caused damage to track and equipment. The only solution was to clean the tracks regularly.

The VakTrak vacuum train created for the New York subway system.

New York City Transit (NYCT) turned to automation. The first French train arrived this spring and was due to enter service in autumn 1997 after testing. It will not be sufficient to clean all 720 miles of track, consequently NYCT has taken an option on three more trains, at (US) $10 million each.

The first VakTrak cleaning train operates in Paris. Montreal, London, Brussels, Milan, Rome, and now New York, have equipped their subway systems with French cleaning trains, and Seoul is now also buying one. "No other system is able to clean the whole width of the track," emphasizes Jean-Louis Defrance, managing director of Neu Transf'air. At the rate of one circuit every month or so, a train collects appreciable quantities of waste. Milan, for example, collects eighty metric tons per year.

The train is equipped with an engine at each end and three coaches, with a suction hood in the middle one, and hoppers for storing the waste in the front and rear. To collect waste more efficiently, the hood first blows it into the air, then vacuums it up. Ducts and nozzles of various sizes, suitable for various track configurations are also available.

After being sucked up, the waste is trapped by a cloth filter and accumulates in hoppers that hold fifteen cubic metres (520 cu. ft.) of material. Particular attention is paid to air quality in the tunnels and stations. Thanks to a filter, the air ejected from the hood contains a maximum of three milligrams of dust per cubic metre of air. The filter itself is continuously cleaned by reverse-blasting compressed air. Thanks to an air flow rate of 280,000 cubic metres per hour (9.9 million cu. ft.), the hood does not lack for suction power.