As the demand for mass transportation burgeons around the world, railway companies are looking for new solutions to address the increasing challenges of moving more people quicker than ever before.
Replacement of old infrastructure combined with new high-speed links is a solution to meet these growing needs. In addition, reduced running costs and energy consumption, improved passenger safety, more attractive outer appearance and better comfort to redress the poor image of crowded mass transport are now standard requirements. Railway companies are looking to nickel-containing stainless steel in railcar construction to help meet these challenges.
X 2000 trains in Sweden
When Swedish state railway company SJ ordered a fleet of high-speed trains in the late 1980s, they needed a solution that would be both safe, comfortable and cost-effective in the long term. Combined with lower maintenance costs and long service life, nickel-containing stainless steel—an austenitic alloy, Type 304 (UNS S30400) in cold-worked condition for enhanced strength—was the optimal choice for the fast and firm X2000 train frames.
The X2000 trains were manufactured by ABB and introduced into service between 1990 and 1998. The material of choice for the train frames was stainless steel supplied by Outokumpu.
The X2000 trains have a special design including a tilting system and radial bogies, which allow for a high speed of 200 kilometer per hour on curved tracks, without compromising passenger comfort and safety. The frame has a high level of bending stiffness which reduces vibrations and increases travel comfort. In addition, Type 304 stainless steel has excellent impact resistance in a collision, enhancing passenger safety.
The trains operate mainly between big cities like Stockholm, Copenhagen, and Gothenburg. ABB’s decision to use stainless steel as the frame material was based on thorough lifecycle analysis, which calculated that in the long-term stainless steel was a lighter, safer and less expensive option than aluminum or carbon steel. For instance, the savings in maintenance costs per railcar over a period of 30 years
were estimated at 100,000 Swedish kronor
(ca. USD 17,500 today), and the weight reduction per car was about 20% compared to carbon steel. The lighter build also means that less energy is needed to propel the train, which translates into considerable energy savings: an estimated 800,000 kWh per car over a period of 30 years.
Now, two decades later, the trains are undergoing a full technical and interior upgrade. However, the original stainless steel frames remain intact and are expected to stay in service for another two decades. The X2000 upgrade project promises to return the entire train fleet back to service with improved reliability and comfort by 2018. This application highlights how crucial it is to use a lifecycle approach when choosing materials. Looking at both costs and environmental impacts as well as selecting the right grade of stainless steel pays off.
LHB coaches for high speed trainsin India
Indian Railways is the largest railway network under single ownership in the world. The system is the lifeblood of the nation, carrying over one billion tonnes of freight per year and more than 23 million passengers every day. It operates about 250,000 wagons and nearly 70,000 passenger coaches.
As India’s economy grows, Indian Railways has a challenging task ahead transporting the increasing traffic demands with line and terminal capacity constraints. While initiatives are afoot to decongest the existing network by introducing high-speed trains, passenger safety has assumed critical importance in the design and materials selected for construction for coach bodies.
With such a large network, there have been a number of fatal accidents over the last few decades, which has led to calls for better structural design for ‘crashworthy’ coaches made of superior material, with discussions intensifying after every major accident.
Ideally, in a vehicle crash, the passenger should be enclosed in a rigid, safe structure with seat belts so that they do not suffer serious injuries. Modern automobiles have adopted this design. The passenger compartment is a safe, rigid cell, and the front and rear of the car are crumple zones that collapse to absorb impact energy.
Indian Railways has understood the importance of nickel-containing stainless steel for the construction of coaches to improve passenger safety and in 2001 they introduced the LHB (Linke Hofmann Busch) coaches from Germany. According to a senior Rail Ministry official, “LHB coaches made of stainless steel have more built-in safety features as they can absorb shock and impact of derailment more effectively and do not topple easily when a train derails, reducing the loss of lives in case of an accident.” Type 304 (UNS S30400) is used for roofing and the trough-floor where the chances of corrosion are high. For water tanks and bio digester toilet containers, Type 316L (UNS S31603) was the material of choice. Each coach roughly uses 10-11 tonnes of stainless steel, of which 40% is austenitic.
In 2016, Indian Railways planned to roll out 4,000 LHB coaches in India, and later announced an aggressive plan at the Rail India Conference 2016 to “make a complete switchover to LHB coaches by 2018.” Indian Railways’ decision to fast-track a complete replacement of steel coaches with nickel-containing stainless steel coaches to ensure the safety of its passengers will no doubt greatly increase the use of nickel-
containing stainless steel in India.