Škoda 15T (also known as Škoda ForCity Alfa) is a 100% low-floor multiple-unit tram developed by VUKV a.s. and built by Škoda Transportation in Pilsen for the Prague tram network. It was a successor to the Škoda 14 T, featuring articulated bogies and more power to correct for problems found during the operation of the 14 T. The 15T has articulated bogies at either end of the train, and Jacobs bogies between the segments. The tram has two double-doors in each segment (or four in bi-directional version) to allow fast boarding of passengers, and one extra side door leading to the driver's cabin.
The Škoda 15T ForCity was developed as highly modular; it is offered with up to five car body sections and 50.6 meters (166 ft 0 in) in length. It may be used on gauges from 950 mm (3 ft 1 3⁄8 in) up to 1,524 mm (5 ft) and the body may be 2,300–2,650 mm (90.6–104.3 in) wide. The tram can be uni-directional or bi-directional. It can have from 60% of wheels driven up to all of the wheels driven for networks in hilly cities. As the bogies are under articulations and don't interfere with the inner space of the body sections, there is unlimited choice of interior lay-out and location of doors.
The basic vehicle length can be modified. It is also possible to couple two or more vehicles. The tram's appearance and front design are user-defined.
The fixed bogies which are used by most 100% low floor trams increase track wear and decrease the speed at which a tram can drive through a curve (usually 4–15 km/h (2–9 mph) on a 20 m (66 ft) radius curve). The 15T is designed to cope with these drawbacks by using Jacobs bogies under the articulations, and pivoting bogies at the ends of the tram.
For a time[when?] the 15T was said to be the only 100% low floor tram in production with full-pivoting bogies. However, the Alstom Citadis X04, an experimental 100% low floor tram currently[when?] being developed with pivoting bogies (but with sections of high floor seating over the bogies), has made an initial production appearance in Istanbul as a modified Citadis 301 (with a fixed centre bogie), and as of 2015[update], a tram with a similar interior arrangement, and all pivoting bogies, is undergoing trials for Helsinki. With the same length of tramcar, the Škoda 15T also has four bogies, compared to three (fixed) bogies (the same as on most 100% low floor trams) on it its predecessor, the Škoda 14 T's, which decreases the load each wheel puts on the track. Most of the tram floor is 350 mm (13.78 in) above the rails, but the height over the bogies is 450 mm (17.72 in) above the rails. The transition is inclined, without interior steps. The corridor above the central bogies is 700 mm (27.56 in) wide.
The bogies can all be driven, or some may be idle, depending on the customer's preferences. The bogies have two axles and two-level springing. The mounted wheels are rubber-sprung, with integrated brake-discs and axle bearings. On the axle bearings there is a combined, dynamically resistant, primary rubber-bonded-metal-sprung bogie framework. This framework supports four traction motors and one (in outer bogies) or two (in inner bogies) sprung swing bolsters. The secondary springing of the swing bolsters is secured by steel coil springs with parallel hydraulic rotating dampers. The swing bolsters have pivot bearings, which facilitate full rotation of the bogie below the body without any limitations.
All bogies are equipped with identical wheels, which have tyres damping rubber pads to minimize noise. Selected bogies could be equipped with a sanding system.
The vehicle is driven by traction units. Each unit consists of traction container on the vehicle roof and of four traction motors, which drive wheels of one driving bogie. Individual wheel drive on respective bogies secures perfect use of adhesive conditions and ideal ride both in bends and on straight lines. There are three-phase synchronous motors with permanent magnet excitation on rotor. They are fixed to the bogie framework from the wheels outside. The traction motors don't use a gear box - they drive tram wheels directly through a mechanically disconnectable jaw clutch.
While the drive is controlled by two control units connected together by fast serial communication, the safety circuits and functions are hardware-resolved.
Braking is mainly done by electrodynamic brake enabling recuperation of the braking energy back to the electrical grid. If there is no need of it, the braking energy is being used primarily for feeding the vehicle's auxiliary equipment with the rest depleted in the brake resistors. The electrodynamic brake is able to automatically run even during grid's voltage failure. In case of failure, braking is automatically done by the system of friction disc brake, which will work until the vehicle comes to a complete halt. The friction disc brake is hydraulically controlled with an electric compression unit. Each bogies is also equipped with a pair of electromagnetic rail brakes with voltage of 24 V DC. The friction disc brake also ensures the parking brake function.
The vehicle has two double doors on each body unit (or four of them on bi-directional version), or alternatively there can be one door each side on each body unit located in place of any of the side panels. The driver has a separate door leading to the driver's cabin. The doors slide outwards. Each door is equipped with an individual control unit, which operates it and communicates with the vehicle central control unit. In selected double-doors area there could be either ramp or lift enabling easy entry for passengers with restricted mobility. There could be also a room for bicycles and prams.
Škoda ForCity won the bidding process of the Prague transport company for 250 new trams in 2005. The order is worth 17 billion CZK (about 68 million CZK per unit (2,3 million € per unit - 1€ 2005=29,6CZK)).
The trials of the first prototype started in 2009, the first rides with passengers started in October 2010 and the last tramcar will be delivered in 2017. The prototype had 3 types of seats - wooden, plastic and with fabric upholstery. Passengers have decided in an internet poll that the wooden seats will be used in the delivered version.
During the delivery of the first batch in 2011, the Prague transport company started negotiations with Škoda regarding the installation of air conditioning in the passenger compartment. It also raised the concern that a 1,000-horsepower streetcar may be unnecessarily powerful and proposed a solution used in the Riga version, which has only three out of four bogies driven. In the view of the transport company the price of additional air conditioning should be covered by eliminating the first bogie's motors. As of May, 2011, it was not yet decided whether this solution will be applied. Firstly there is issue that participants in the original tender may contest the change and require a new competition; secondly it has to be tested whether the 15T without full adhesion would be able to drive on Prague's hilly network.
In May 2014, due to financial problems for the City of Prague, the Prague transport company and Škoda Transportation renegotiated the contract to provide for four extra years for delivery of the order and for fitting of full air-conditioning and WiFi in the last 125 trams of the order. By June, 2014, the first 100 trams of the order had been delivered and the first of the modified trams (from the second half of the order) will be delivered in 2015.
In May 2008 Škoda made a contract with the Riga transport company (Latvia) for delivery of 20 trams (with option for another 32) worth 1,3 billion CZK (about 65 million CZK per unit (2,6 million € per unit - 1€ 2008 = 25CZK)). The bidding process started in 2007 and altogether 9 companies took part in it. The Riga variant is three-segmented, like the Prague version, with air-conditioning for whole tram (Prague only for driver's cabin) and it is in white-blue livery. Unlike Prague's version, which has all bogies driven due to difficult adhesive conditions (Prague has hilly terrain), the Riga tram has 3 bogies driven (the 1st bogie doesn't have motors). The tram has upholstered seats similar to those in Škoda trolleybuses used in Riga.
The first tram was delivered to Riga in March, 2010, the second in August 2010 and the other 18 were delivered before the end of 2011. The first rides with passengers were in June, 2010 after preceding test-drives.
There are also 6 four-segmented tramcars (41 m long) made for Riga, Latvia, as the town decided to apply a part of the pre-agreed option of 32 (which was part of the previous order for 20). These were delivered between June and October 2012.
In April 2016 Riga Transport (RS) awarded Škoda Transportation a €62.6m contract to supply 20 more, 15T ForCity low-floor trams. The order comprises 15 three-section vehicles and five four-section LRVs. All 20 vehicles are due to be delivered next year. The 1,524 mm (60.0 in)-gauge 600 V DC vehicles will be used on Line 4, which links Riga Central Market with Imanta.
Several unsuccessful tenders have been made by Škoda for the ForCity tram in other cities.
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