High-Speed Railways (HSR) are a hot topic in the Rail industry since the safer High-Speed trains have proved the case. As many countries compete to build High-Speed Railways, developed countries are forced to upgrade the existing tracks to meet the need for speed. This article just analyses the conventional railways with HSR. Today, HSR’s speed, punctuality, and, above all, safety has not only achieved celebrated status among travellers throughout the world but have fundamentally transformed passenger transport in several countries.
High-speed rail can mean many things, depending on the context. For a traveller, HSR typically delivers comfort, speed, punctuality, safety and reliability just to begin—especially when journeying between central city business districts at a time of increasing airline delays.
Since its introduction in Japan in the 1960s, High-Speed Rail has now become a worldwide phenomenon and investments are being developed to connect many of the world’s largest and growing cities. However, these nations’ decision-makers face a complex array of choices in terms of technologies and operating systems and wrestle with adapting elements of established technologies to their local needs. Today, HSR remains a powerful symbol of a nation’s commitment to infrastructure.
What is HSR?
High-speed rail (HSR) is a type of passenger rail transport that operates significantly faster than the normal speed of rail traffic. EC Directive 96/58 define high-speed rail as systems of rolling stock and infrastructure which regularly operate at or above 250 km/h on new tracks, or 200 km/h on existing tracks.
Current Speeds of HSR
It has been more than 50 years since the first high-speed rail (HSR) train captured the global imagination as it zipped past Mount Fuji 10 days before the opening of the 1964 Tokyo Olympics.
In Japan, Shinkansen lines run at speeds in excess of 260 km/h (160 mph) and are built using standard gauge tracks with no at-grade crossings. In China, high-speed conventional rail lines operate at top speeds of 350 km/h (220 mph). The world record for conventional high-speed rail is held by the V150, a specially configured version of Alstom’s TGV which clocked 574.8 km/h (357.2 mph) on a test run.
Viability of HSR over Conventional Railways
High-Speed Rail operations can’t be carried out like conventional rail operations on classic lines. This is due to the high speed of the trains. Therefore, always a large amount of time is needed for a stop. Also, the distances between the stops must increase in order to achieve sufficient efficiency. The efficiency of a railway system means the quotient of commercial speed divided by the maximum speed of the Electric Multiple Unit (EMU) generating the commercial speed.
HSR can play an important role in a nation’s transportation network, depending on a range of demographic, geographic, social and economic factors. Determining when it is the right solution is as much an art as a science, requiring a view that balances local preferences with big-picture economic and engineering practicalities.
While a host of weather events can severely disrupt both air and road transport, HSR often continues operating.
Safety is, finally, the most profound aspect of any transport mode’s “reliability”—and here HSR’s record is even more astonishing than its punctuality.
But the net economic costs of HSR’s social benefits, he argues, have to be weighed against the net costs and benefits of other investments.
Of course, the reality is that HSR is as viable as any other transport option, given all the costs— social, economic, and environmental—but that is not always clear to a public that must ultimately pay for a high-speed line’s construction.
In the end, choosing HSR requires careful study, balancing needs, expectations, and, above all, competing claims on public expenditures. Travellers around the world have embraced it.
Benefits of HSR
- Time savings
- Overcrowding relief
- Net revenue
- Environmental benefits
Cost of HSR
In the UK, a new double-track railway, like HS2, will cost around £76million per km.
A modern train will use up to £1.5million per vehicle.
Signalling systems will be up to £ 3 million/km.
Power supplies and communications will fall into similar price ranges.
HSR Operating Methods
Operating High-Speed Rail (HSR) we can distinguish between two different kinds of Operation methods.
Operational Method 1: High-speed EMUs run exclusively over their own high-speed tracks, which they don’t need to share with other trains. The fundamental reason for this state of affairs must be seen in the different gauges between the High-Speed network and the classic network.
Operational Method 2: High-Speed Trains (HST) also run, more or less, on classic lines.
Categories of HSR according to European Union
– Category I: Specially built high-speed lines equipped for speeds generally equal to or greater than 250 km/h,
– Category II: specially upgraded high-speed lines equipped for speeds of the order of 200 km/h,
– Category III: Specially upgraded high-speed lines or lines specially built for high speed, which have special features as a result of topographical, relief, environmental or town
All categories of the line shall allow the passage of trains with a length of 400 metres and a maximum weight of 1000 tonnes.
Interoperability of HSR
Interoperability simply means that technical specifications for HSR are harmonized on an EU-wide basis so that HSR can cross national boundaries. Since both France and Germany have made their HSR systems integrated and interoperable with their previously existing rail networks, this has resulted in the effective integration of German and French railway networks at the heart of a growing, Europe-wide HSR network.
Line capacity is the ability of a railway to carry a certain number of trains in one direction on one track over a certain period. It is determined by how many trains you can run on a track in this direction in an hour and is expressed as trains per hour (tph).
Line capacity will depend on
- train performance, particularly braking and acceleration
- train length
- Train Controlling system
- the infrastructure
- power availability
- possible maximum line speed
- the station spacing
- the terminal design
- the track gradients
- the railway control (signalling) systems
- dwell times at stations
- terminal operations
- allowances for speed restrictions
High-speed lines comprise:
– Specially built high-speed lines equipped for speeds generally equal to or greater than 250 km/h,
– Specially upgraded high-speed lines equipped for speeds of the order of 200 km/h,
– specially upgraded high-speed lines which have special features as a result of topographical, relief or town-planning constraints, on which the speed must be adapted to each case
Factors to consider on Line Speed
When designing a new or upgraded high-speed line, consideration should be given to other trains, which may be authorised on the line.
Rolling stock complying with the High-Speed Rolling Stock must be able to negotiate track compliance with limiting values set out in the present.
From an infrastructure perspective, the most significant issues are probably those relating to:
a) Structure gauge.
b) Overhead line interface.
c) Signalling equipment interface
Functional and technical specifications
The elements characterising the Infrastructure domain are
- Nominal track gauge
- Minimum infrastructure gauge
- Distance between track centres
- Maximum rising and falling gradients
- Minimum radius of curvature
- Track cant
- Cant deficiency
- Equivalent conicity
- Track geometrical quality and limits on isolated defects
- Rail inclination
- Railhead profile
- Switches and crossings
- Track resistance
- Traffic loads on structures
- Global track stiffness
- Maximum pressure variation in tunnels
- Effects of crosswinds
- Electrical characteristics
- Noise and vibrations
- Fire safety and safety in railway tunnels
- Access to or intrusion into line installations
- Lateral space for passengers and onboard staff in the event of detrainment outside of a station
- Distance markers
- Length of stabling tracks and other locations with very low speed
- Fixed installations for servicing trains
- Ballast pick-up
- Maintenance rules
List of basic parameters to consider in the design
Structure gauge: The infrastructure must be constructed so as to allow safe clearance for the passage of trains complying with the High-Speed Rolling Stock.
The minimum infrastructure gauge is defined by a given swept volume inside which no obstacle must be located or intrude. This volume is determined on the basis of a reference kinematic profile and takes into account the gauge of catenary and the gauge for lower parts. The structure gauge shall be set on the basis of the gauge set out for all the trains operating on the line. Calculations of the structure gauge shall be done using the kinematic method. Where overhead electrification is provided, the pantograph gauges are set out as well.
Distance between track centres: The nominal distance between track centres shall be 3 400 mm on a straight track and curved track with a radius of 400 m or greater.
The distance between track centres shall be set on the basis of the gauge set out for the specific project. Where appropriate the minimum distance between track centres shall also take into account aerodynamic effects. Where appropriate the minimum distance between track centres shall also take into account aerodynamic effects.
Maximum gradients :
Gradients as steep are permitted for main tracks at the design phase provided the ‘’envelope’’ requirements are observed. The design of gradients for new lines is a complex subject and needs to be considered with other system requirements. It is likely that any new high-speed line needs to connect with the existing network.
Minimum radius of horizontal curve:
The minimum design radius of horizontal curve shall be selected with regard to the local design speed of the curve. When designing the lines for high-speed operation, the minimum radius of curvature selected shall be such that, for the cant set for the curve under consideration the cant deficiency does not exceed, when running at the maximum speed for which the line is planned
Minimum radius of vertical curve:
When designing the lines for high-speed operation, the minimum radius of curvature selected shall be such that, for the cant set for the curve under consideration the cant deficiency does not exceed, when running at the maximum speed for which the line is planned
Nominal track gauge :
Nominal Track gauge is mostly fixed to standard value and for Europe is always 1435 mm
The highest cant on a section of the line shall be published in the Register of Infrastructure. The design cant on tracks adjacent to station platforms is limited.
Rate of change of cant (as a function of time) : The design of cants for new lines is a complex subject and needs to be considered with other system requirements.
The maximum rate of change of cant through a transition shall be calculated at the maximum speed permitted for trains not fitted with a cant deficiency compensation system. The design of cants for new lines is a complex subject and needs to be considered with other system requirements.
Cant deficiency: In curves, cant deficiency is the difference, expressed in mm, between the applied cant on the track and the equilibrium cant for the vehicle at the particular stated speed. The maximum cant deficiency at which trains are permitted to run shall take account of the acceptance criteria of the vehicles concerned.
The design for the maximum cant deficiency for new lines is a complex subject and needs to be considered with other system requirements for the project.
Equivalent conicity: The wheel-rail interface is fundamental to explaining the dynamic running behaviour of a railway vehicle. It needs therefore to be understood and, among the parameters by which it is characterised, the one called equivalent conicity plays an essential role since it allows the satisfactory appreciation of the wheel-rail contact, on tangent tracks and on large-radius curves.
Design values of track gauge, rail head profile and rail inclination for plain line shall be selected to ensure that the equivalent conicity limits
Railhead profile for the plain line :
The design of railhead profiles for plain lines shall comprise:
- a lateral slope on the side of the railhead angled between vertical and reference to the vertical axis of the railhead;
- a minimum radius of at the gauge corner;
- a range of horizontal distance between the crown of the rail and the tangent point
- a defined vertical distance between the top of this lateral slope and the top of the rail
The rail shall be inclined towards the centre of the track. The nominal rail inclination for the GB network is 1/20. If a different nominal value is selected then compatibility with the existing network will be difficult to achieve and through the running of vehicles could give rise to problems.