railway track

SLAB TRACK ROADBEDS IN GERMANY

Chicago 13.-15. September

S l T r la b T ra c k k R R oad bed s i n G G er many - I Im pl ement at i io n and E x per i E ie nc e-

Dipl.-Ing. Jürgen Mörscher DB Netz AG

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Table of contents Page 1

Introduction........................................................................................................ 3

2

New high-speed technology .............................................................................. 4 2.1 Slab tracks ..................................................................................................... 4 2.2 Slab track licensing ........................................................................................ 7 2.3 Slab track stock on the DB network ............................................................... 7 2.4 Slab track technology..................................................................................... 8 2.5 Service trials for slab track near Waghäusel.................................................. 9 2.6 Developments in the quality of the track geometry of Slab Track ................ 13 2.7 Future use of slab track ............................................................................... 14 2.8 Ballast track ................................................................................................. 14

3

Conclusion....................................................................................................... 15

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Slab Track Roadbeds in Germany -Implementation and Experience -

1 Introduction One of the objectives of the 1994 railway reform is to increase DB AG’s competitiveness, thereby ensuring its future survival in the market is guaranteed without public subsidies. This cannot be achieved without continually searching for innovative ideas and technology and resolutely implementing them in every area of rail activity. With its long-life facilities, track infrastructure represents a huge fixed cost factor in DB Netz’s company accounts. Only hard, sustained meticulous work generally accompanied by detailed improvements can have a positive impact on this cost factor. Spectacular successes or advances in leaps and bounds are rare indeed. Although the long-term effect induced by technology is an uncomfortable reality in track infrastructure, it is nevertheless an incontrovertible fact. It means that everyone concerned has to think, plan and act long term. It has sometimes taken decades for new technology to be tried and tested in practice before it has proven itself. Deutsche Bahn currently operates a network of 40,000 km of track with 71,000 km of railway lines and 100,000 switches. These facilities have to be kept in good shape and must pay their way for both our customers – passenger and freight traffic – and for third parties. This means focusing on • • • • •

guaranteeing safety guaranteeing availability ensuring comfort complying with environmental legislation and proving profitability.

Overriding all these objectives, which are achieved by facility maintenance, the prime in-house necessity is of course for cost cutting, without which no company can remain competitive.

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New high-speed technology Slab tracks

In future, new stretches of track in the high-speed area will, however, be required to satisfy even higher quality standards. These requirements include: • • • • • • •

lower life-cycle costs greater availability stable, permanent track level with maximum ride comfort precisely defined track elasticity minimal maintenance costs use of eddy-current brakes and sufficient reserves for future generations of vehicles with even greater speeds.

All these premises call for further innovative developments and alternative track designs. In terms of present-day scientific knowledge, slab track designs, as installed and tested in all manner of developments on more than 200 km of DB AG track, most readily satisfy the requirements for high speed. Slab track is defined as a type of track based on a frost-protected concrete or asphalt layer precisely defined in terms of its deflection and damping. It requires a low-deformation support as used on bridges and in tunnels. Earthworks therefore require a multilayered arrangement of the load-carrying system with increasing stiffness in order to guarantee the required long-term resistance. Slab track designs may be classified as follows: • • •

compact construction with and without sleepers/track panel [page 5] supported construction exclusively with sleepers/track panel and [page 6] special solutions.

These designs can also be used on earthworks and in tunnels. Switches on slab track can likewise be inserted into this basic structure. With supported switches, a further difference has to be made between elastic base plate bedding (ERL) and elastic sleeper bedding (ESL). There are further differentiations depending on the type of construction material used in the upper bonded base layer (concrete, asphalt). The terms ‘concrete construction’ and ‘asphalt construction’ are also common here. Only modified forms of slab track can be used on bridges.The systems must enable relative movement to effect a reduction in the friction forces between track and bridge caused by temperature.

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Compact design slab track system RHEDA

UIC 60 rail 2 600 mm 1 435 mm

fastening concrete sleeper infill concrete concrete trough

hydraulically bonded base course


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Supported design slab track system ATD

transverse force plinth UIC 60 rail 2 600 mm 1 435 mm

securing element two-block sleeper

asphalt base course


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Supported design slab track system ATD

transverse force plinth UIC 60 rail 2 600 mm 1 435 mm

securing element two-block sleeper

asphalt base course hydraulically bonded base course


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Slab track licensing

The use of new slab tracks in the DB AG rail network is subject to licensing under public law or approval in individual cases (ZiE) from the Eisenbahn-Bundesamt [Federal Railway Office] (EBA).This certifies that the slab track is perfectly safe and technically feasible in terms of state-of-the art technology. The applicant must submit a design specification, proof of static rigidity, expert opinions and the results of lab tests and trials along with the licence application. Once the railway authorities have studied and evaluated the construction design for the slab track or its system components, they issue a general licence or a licence for operational testing. The licence for operational testing is generally subject to a fixed period of time. In addition to the EBA licence, a user declaration is required from DB AG f or the slab track or its system components to be used in the rail network.This user declaration is the rail company’s approval for the new system to be used in a specific case.


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Slab track licensing

The use of new slab tracks in the DB AG rail network is subject to licensing under public law or approval in individual cases (ZiE) from the Eisenbahn-Bundesamt [Federal Railway Office] (EBA).This certifies that the slab track is perfectly safe and technically feasible in terms of state-of-the art technology. The applicant must submit a design specification, proof of static rigidity, expert opinions and the results of lab tests and trials along with the licence application. Once the railway authorities have studied and evaluated the construction design for the slab track or its system components, they issue a general licence or a licence for operational testing. The licence for operational testing is generally subject to a fixed period of time. In addition to the EBA licence, a user declaration is required from DB AG f or the slab track or its system components to be used in the rail network.This user declaration is the rail company’s approval for the new system to be used in a specific case. The system can be granted a general licence and introduced as a DB AG standard design when its technical suitability has been proven by operational testing over several years with at least 3 winter periods or a traffic load of not less than 150 million tonnes.

2.3

Slab track stock on the DB network

On 27 September 1998 the Hanover-Berlin high-speed rail link became fully operational after a 6-year construction period. This extended Deutsche Bahn’s highspeed network by a further 263 km of track. A total of approximately 90 km of the line (about 180 km of rail) comprises slab track. A further 28 clothoid switches for high-speed traffic on slab track were installed in crossover connections and at turn-out points (26 switches on concrete base layer, 2 switches on asphalt layer). The slab track systems installed are standard DB AG designs and design modifications, the technical suitability of which has been proven by many years of testing or by special tests. From now on these construction designs must prove themselves under the conditions of high-speed traffic. With the Hanover-Berlin high-speed rail link and the preceding S-Bahn and intercity tracks (about 26 km) becoming operational between Berlin Zoo and Berlin Ostbahnhof in September 1996 and May 1998 respectively, the length of slab track has increased to approximately 340 km in total.

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Slab track technology

Of the slab track constructed so far, 76% is built on a concrete base layer (BTS) and 24% on an asphalt base layer (ATS). Permanent track level and low maintenance costs are expected of the slab track within its planned service life. This presupposes a high quality of planning and construction. As the track level is fixed, the scope for correction work is limited. The vertical correction is 20 mm and the lateral correction only 4 mm. During construction, as a rule, the actual problems have been in the construction quality. At present the design quality is inadequate, meaning that structural inaccuracies call for later corrective rail tolerances. Only a consistent quality assurance system adhered to by the purchaser and the supplier can remedy this, resulting in defects in the manufacturing tolerance being detected at an early stage and in extreme cases the structural component dismantled and re-manufactured. The slab track must be based on a load-bearing frost-protected subsoil, and the hydrological conditions must not restrict the load-bearing capacity (groundwater table ≥ 1.5 m below running surface). Any problem locations or problem areas detected during the site investigation must be brought into line with the requirements by taking geotechnical measures (underpinning the foundations). The base layer (BTS) must be made on exactly the right level for the supported designs of the slab track ( ± 2 mm). This applies to both concrete and asphalt constructions. The concrete surface must guarantee the planar bearing of the sleepers and the supporting switches when manufactured and after corrections.The same precision requirements must be observed for the asphalt base layer (ATS) as for concrete layers with supported constructions. It is as hard as ever to make a comparative evaluation of the new track system, and savings on maintenance costs are only quantifiable to a limited extent. It is also difficult to substantiate the higher standards attainable with the slab track in terms of working and operating safety, availability, track geometry and comfort using incontestable figures or value factors that can be included in profitability studies. In comparison with a ballast track appropriate to the conditions, the justifiable cost factor for the slab track in terms of modern technology is about 1.4. The factor obtained for the sleeper-less designs in the Waghäusel construction project was 1.2. The cost factor for the least expensive designs used in the Hanover-Berlin highspeed rail link was about 1.5. Higher production costs must be offset in turn by cutting costs for maintenance and through income generated from the greater availability of the track. Knowledge and experience confirm that with the correct design of the appropriate quality slab tracks can meet the demands placed upon them. Results to date of monitoring show that no maintenance work was necessitated by the system itself. The costs recorded were restricted to regular inspections and corrections on transitions to the ballast track.

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Print-outs obtained during inspection runs with track measuring cars confirmed the permanently stable track level of the slab track, i.e. the track level quality at the time of going into service is practically maintained. DB’s goal is to provide a track infrastructure which perfectly matches customer requirements. This track infrastructure must have a high standard of safety and guarantee short journey times in great comfort. And all of this must be achieved at market track prices. The requirements for this on the construction side are low manufacturing costs and low maintenance costs.

2.5

Service trials for slab track near Waghäusel

A stretch of track of approximately 3km between Karlsruhe and Mannheim went into operation in 1996 for service trials on seven different types of Slab Track. Of the 7 types, 6 were of compact design and one a supported version. The route section is traversed at a speed of 160 km/h. The line load totals some 110,000 tonnes a day.

Three of the 7 Slab track designs are described below:

Hochtief, Schreck-Mieves A BTS is set up on an hydraulically bonded base course and four reinforcement binders are jiggled into ready-mixed concrete for each individual rail support. Afterwards the individual rail supports are adjusted using a setting frame so that the level and height are exact and produced from cast-in-situ concrete reinforced with steel fibre. In conjunction with the BTS, they form a monolithic system. Rain water is directly drained off the surface of the BTS.

Züblin BTE Elastically mounted base plates are used as rail fastenings resting on the jointless concrete base plate produced by a concrete extruding machine and reinforced to prevent crack formation. To ensure rapid water drainage around the fastenings, the concrete base plate is equipped with two continuous reinforcements interrupted every 6.50 m for all the water to drain away.

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Waghäusel: Slab track Hochtief/Schreck-Mieves


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Waghäusel: Slab track system BTE Züblin

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Waghäusel: Slab track system BTE Züblin

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Waghäusel: Slab track system Crailsheim Leonhard Weiss ( C ) A R E M A ( R ) 2 0 0 0

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Waghäusel: Slab track system Crailsheim Leonhard Weiss ( C ) A R E M A ( R ) 2 0 0 0


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Leonhard Weiss FFC A BTS is set up on an hydraulically bonded base course where the individual rail supports to accommodate the Loarv 300 rail mounting are initially roughly produced as an indentation in unset concrete. Immediately afterwards a finisher which re-treats the individual rail supports still to be moulded achieves the precision setting of level and height. Drainage is provided by the openings between each rail support.

2.6

Developments in the quality of the track geometry of Slab track

The quality of the geometry of a given section of track can be described using what is referred to as the Q value. This is arrived at by taking the values for longitudinal level, cross-level, direction and track twisting produced by a track-measuring train


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Leonhard Weiss FFC A BTS is set up on an hydraulically bonded base course where the individual rail supports to accommodate the Loarv 300 rail mounting are initially roughly produced as an indentation in unset concrete. Immediately afterwards a finisher which re-treats the individual rail supports still to be moulded achieves the precision setting of level and height. Drainage is provided by the openings between each rail support.

2.6

Developments in the quality of the track geometry of Slab track

The quality of the geometry of a given section of track can be described using what is referred to as the Q value. This is arrived at by taking the values for longitudinal level, cross-level, direction and track twisting produced by a track-measuring train and combining them into a single value using a weighting formula. W here the Q value reaches 100, maintenance works are required. In the picture below, developments in the quality of the track geometry on a portion of the high-speed line between Hanover and Würzburg are shown as an example of the track geometry rating (Q value) of Slab Track (RHEDA Sengeberg). It can be seen that the geometry of the track did not change between 1990, the year it was commissioned, and 1995. The Q value is less than 15.

Q-value

Date of recording 1990 1995 Ballasted track

Ballastless track

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Ballasted track

SLAB TRACK ROADBEDS IN GERMANY 2.7

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Future use of slab track

In the high-speed sector, the ballast-free track is becoming increasingly important for DB AG on account of technical requirements. Its uses and areas of application have expanded considerably thanks to its impressive level performance under operating conditions and the innovation drive in recent years. The high-speed 204 km Cologne-Rhine/Main line is constructed entirely of slab track. DB AG is planning further new lines and extensions to existing lines. The range of slab tracks and system components on the market calls for systematisation and limitation or standardisation without barriers being set up that restrict innovation. This requires evaluation and selection criteria by which the intrinsic system characteristics of a particular construction design can be evaluated in terms of their functional advantages and disadvantages. DB is setting about doing this. What is further required is a directive stipulating the limits for using and applying the licensed slab track construction designs correlating to the track characteristics. On this basis the various slab track construction designs that are different in terms of costs and technical features can be applied in direct relation to the constructionspecific and line-specific conditions (speed, volume of traffic on the line, geometry, type of traffic, constructions, foundation conditions, etc.). This optimisation potential should be maximised in the interest of a broad, flexible use of slab track and to further reduce costs. DB AG will avail itself of the technical and economic opportunities offered by the slab track on the new lines and extensions to existing lines on the high-speed network as well as on particularly demanding lines and constructions. In this sector, the switches have been truly set towards slab track!

2.8

Ballast track

Since 1991, Deutsche Bahn has been operating on its new stretches of track at speeds of 250 km/h to 280 km/h with mixed traffic, i.e. with high-speed passenger and heavy freight traffic on the same rails, built as standard European rails on ballast. The earthworks, base layers and ballast bed were packed high to prevent settlement and consequently manifest low elasticity when operating today with rail depressions of 0.3-0.7 mm under a 200 kN ICE axle. This results in a hard vehicle ride partially linked with ICE vibrations and in certain problem areas (such as bridge abutments, tunnel/dam transitions or ballast/slab track transitions), ballast wear with rising maintenance costs. What is therefore required for new stretches of track in the future with speeds of up to 300 km/h is to continue perfecting the ballast track in terms of long-term (C) AREMA (R) 2000


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performance and its safety against track buckling, even with the use of eddy-current brakes. The result is • • • • •

increased ballast bed thickness of 40 cm the tried and tested UIC 60 rail (grade A) the heavier B 75 pre-stressed concrete sleeper with a sleeper spacing of 63 cm the new highly-elastic Loarv 300 rail mounting as used in the Rheda slab track, for instance in future, it is the intention to use under-ballast mats on bridges and in the connecting back-fill areas.

This newly developed state-of-the-art high-speed ballast track has been integrated into the 13 km Stendal southern loop as part of the Hanover-Berlin high-speed link in line with experience in the high-speed sector. From 1998 onwards, it must prove its worth.

Improved ballast track on the new HannoverBerlin line with the B75 pre-stressed concrete sleeper

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Conclusion

The ability of the railways to remain competitive is inextricably linked with the criteria of safety, reliability and comfort whilst observing the criteria of profitability. Applying

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trend-setting technology in both the construction of new track and maintenance of the traditional network is a corporate obligation.

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railway track

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