SLAB TRACK Recent Developments In Slab Track - Esveld
finalEsveld Slabtrack.qxd23/5/0310:08 amPage 1SLAB TRACKRecent developments inslab track Coenraad Esveld, Professor of Railway Engineering, Delft University of Technology DelftWith the design of railway lines factors like life cyclecost, construction time, availability and durability playan increasingly important role. In this respect, nonballasted track concepts offer good opportunities.nous and capable of bearing the loads imposed. Theslabs may be prefabricated or poured on site. Thehigh level of investment required has preventedwidespread use of slab track on open line so far.However, on the basis of life cycle costs a differentpicture is obtained [1]. The greatest savings will beachieved in tunnels and on bridges. The use of moreefficient construction methods, of the type used inthe road construction industry, could reduce construction costs further still.With the growth of traffic intensity itbecomes more and more difficult to carryout maintenance and renewal work. InThe Netherlands, night time possessions often lastno longer than 5 hours, and on the future high speedline in Korea (435 km from Seoul to Pusan) the maximum effective possession is estimated at no morethan 11/2 hours per night. In this respect, the currentincrease in popularity of low-maintenance trackdesigns is not surprising.In the past, new projects were mainly assessed onthe basis of investment costs, whereas today the principle of life cycle costing is strongly emerging. As aresult of this new attitude, ballastedtrack concepts will loose attractiveness in favour of slab track systems.General considerationsPresently all over the world non-ballasted track concepts are beingapplied, although still at a moderatevolume. The great advantages of suchstructures can be summarised as follows: Reduction of structure height; Lower maintenance requirementsand hence higher availability; Increased service life; High lateral track resistancewhich allows future speedincreases in combination with tilting technology; No problems with churning ofballast particles at high-speed.Design principlesGenerally speaking there are two ways of designingslab track. According to the German school, basedon highway design, the supporting layer should havea substantial bearing stiffness, represented by themodulus of elasticity Ev2 * 120 N/mm2. Thisrequirement refers in particular to slabs on a subgrade and is originated by the fact that incoherentFig. 1: Shinkansen slab trackblock structures, having no bending resistance, couldbe used. This requirement also covers the conditionthat no differential settlements may occur. Slabsdesigned in this way only contain reinforcement inIf the low-maintenance characteristics of slab trackon open line are to be retained, great care must betaken to ensure that the subgrade layers are homoge-european railway review81
finalEsveld Slabtrack.qxd23/5/0310:08 amPage 2the neutral axis to control crack width in the concrete. This is standard practice in Germany. On engineering structures like bridges and tunnels, providingrigid supporting conditions, this is a logical solution.However, when slabs are built on subgrades oftenmassive soil improvements are required, which makeslab tracks financially unattractive.The second way of constructing slabs, especiallyon soils where some settlements may be expected, iswith reinforcement at the top and at the bottom ofthe slab to take bending stresses and axial forces.Various studies at TU Delft have shown that relatively high reinforcement percentages of about 1.5 %for a B35 concrete [2, 3, 4, 5, 6]. On the other handonly very limited soil improvements are necessary.If no bending resistance is required, prefabricated slab sections can be used. On bridges this hasthe advantage that the influence of bending of the500 km of double track. By 1993, a good 1 400 kmof this had been built (double track), of which morethan 1 000 km consists of ballastless double track. InFig. 2: Rheda 2000Japan, ballastless track always consists of prefabricated slabs just under 5 m long. The percentage ofballastless track varies considerably from line to line.The newer lines include a higher percentage (up to96 %). The slab track design has remained virtuallyunchanged since the first sections were laid in 1972.The Shinkansen slab track (Figure 1, pg. 81) consists of a sublayer stabilised using cement, cylindrical“stoppers” to prevent lateral and longitudinal movement, reinforced pre-stressed concrete slabs measuring 4.93 m x 2.34 m x 0.19 m (4.95 m x 2.34 m x 0.16m in tunnels) and asphalt cement mortar injectedunder and between the slabs. The slabs weighapproximately 5 tonnes.Ballastless track was undergoing rapid development in Germany. Since 1996, DB has been operating a test track in Karlsruhe consisting of seven newtypes of ballastless track. The best-known Germandesign is the Rheda system. There are numerousvariants which indicate that the initial designs werenot completely successful. The most developedRheda system is Rheda 2000 [7]. By eliminating theFig. 3: Bögl slab track systembridge has no influence on the bending stresses in thetrack slab.If (semi) continuous slabs are applied the construction method can consist of either pouring theconcrete into a casing, or constructing continuouslyusing a slipform paver. The price is, to a large extent,determined by the building efficiency.Especially for slab tracks it is important to control the track geometry carefully during construction, as corrections afterwards are difficult. Perhapseven more important is to make the welds at verytight tolerances to avoid impact loads which have astrong negative influence on the service life of theentire structure.Non-ballasted systems in useJapan was effectively the birthplace of high speedrail. Development work on the Shinkansen networkstarted at the end of the 1950s, and the first line(between Tokyo and Osaka) opened in autumn 1964.Five lines are currently in service and a sixth is underconstruction. Government plans dating back to 1970specify a national Japanese high speed network of 3Fig 4.Edilon Block Systemconventional concrete trough, a significant simplification of the overall system con-figuration wasachieved. As a result, the entire cross section of theslab has become one monolithic component. Due tothe elimination of the trough and the use of twinblock sleepers, a considerable reduction of the struc-european railway review82
finalEsveld Slabtrack.qxd23/5/0310:08 amPage 3tural height could be achieved as is revealed by thedimensions in Figure 2, pg. 82.Fig. 5: Embedded rail track near Best (NL)In Germany a prefabricated slab track system,produced by Bögl, is in use. This system is largelysimilar to Shinkansen slabs except that the Bögl slabsare made of B55 steel fibre reinforced concrete andare 20 cm thick, 6.45 m long, and 2.55 or 2.80 mwide. The slabs are pre-stressed in lateral direction;in longitudinal direction traditional reinforcement isapplied. Spindles integrated in the slabs provide aneasy and quick adjustment of the slabs (Figure 3,pg. 82). The slabs are connected longitudinally bypost-tensioned steel rods in the neutral axis.The infrastructure of the High-Speed Line Southin The Netherlands is built according to a so-calledDBFM contract (Design, Build, Finance, Maintain)and was awarded to Infraspeed, a consortium comprised of Fluor Daniel, Siemens and KoninklijkeBAM Groep. In this contract the availability of theinfrastructure is guaranteed at a specified level for 25years. The track consists of a low viaduct consistingof a piled concrete slab, with on top a separate slabwith Rheda 2000 track. Both supporting structureand Rheda slab are dilated at intervals of 35 m tolimit the longitudinal forces in the concrete andthe displacements at the end of the structure. Thevertical relative displacements between the substructure elements at the expansion should be confinedto 2mm.The French Stedef system is most often used intunnels, especially for metro systems. However, thetechnique is also used on high speed networks. Arubber boot under the sleeper provides a high degreeFig. 6: Low niose SA 42of elasticity, which ensures good noise and vibrationinsulation. The Sonneville Low Vibration track isclosely related to the Stedef system. This is a block
finalEsveld Slabtrack.qxd23/5/0310:08 amPage 4track design, which, like Stedef, also uses a rubberboot. Applications include the Channel Tunnel.Another twinblock variant related to Stedef is theSwiss Walo system, mainly used in tunnels. A specialference is one of the major sources for the development of corrugation [8].Prorail has over 20 years experience with this system, and it has proved to require little maintenance.Figure 5, pg. 83 illustrates the cross sectionof a 3 km slab track section near Best in TheNetherlands which was built in 1999.The traditional ERS concept still containsthe conventional UIC 54 rail. However, anoptimised rail concept had been developed in1998, as depicted in Figure 6, pg. 83. ThisSA42 rail is capable of carrying 225 kN axleloads and produced 5 dB(A) less noise. Anadditional advantage is the substantial reduction of polyurethane. This new rail conceptwas installed in the previously discussed testtrack near Best over a length of 150 m.A similar low noise solution was proposed by Balfour Beatty [9]. In this case tooa block rail is applied to achieve improvedacoustic properties and low structure height.This so-called BB Embedded rail is depictedis Figure 7. The block rail, together with padand shell is positioned and this assembly isthen grouted into the concrete. An advantage is that the rail can be replaced afterwards relatively easily.The examples so far pertained to concrete. A newdevelopment in The Netherlands is an embedded railstructure in asphalt pavement, referred to as ERIAFig. 7: Balfour Beatty embedded railslipform paver lays a concrete slab, following whichthe sleepers – fitted with rubber boots – are placed inposition and cast into place.The Edilon block track system (Figure 4, pg. 82)falls into the same category, and is mainly used forbridges and tunnels. Under this (top-down) system,the first step is to place the rails and blocks in position.The blocks are then cast in using Corkelast, to providethe necessary elastic support. Important applicationsinclude 100 km on Prorail, the Dutch Infra company,and on light rail systems in the Netherlands andapproximately 100 km on Madrid metro.Ballastless track has been little used in Italy. In1992, FS had less than 100 km of ballastless track, ofwhich 2 x 5.4 km were located on the Rome-Florencehigh speed line. This track, supplied by IPA, is basedon the Japanese system mentioned above.Fig. 8: ERIA polyurethane varientEmbedded rail structuresAll the designs mentioned so far were based on therail being supported at discrete points – the sleeperprinciple. Since 1976, a continuously supported railsystem has been in use in The Netherlands on a smallscale. The system is known as the Embedded RailStructure (ERS), and involves providing continuoussupport for the rail by means of a compound consisting of Corkelast (a cork / polyurethane mixture).The great advantage of this design is that the track isbuilt “top-down”, which means that tolerances in thesupporting structure have no effect on the trackgeometry obtained. Another major advantage is thatthe wheel does not experience any difference in vertical stiffness like in sleepered track. This stiffness dif-(Embedded Rail In Asphalt) [10]. This is a specialsolution for trams and light rail in urban areas. Thissilent rail structure is integrated into the total pavement, including crossings. Two variants will be tested:The embedded rail prefabricated in a steel trough,which is fixed into a combi-layer of very open asphaltconcrete, filled up with a cement slurry. In the secondvariant the bitumen in the upper 10 cm has beenreplaced by the much stronger polyurethane toreplace the steel trough. Finite element calculationsshowed that these measures were necessary to withstand in particular the transverse wheel loads oftrucks. Figure 8, pg. 84 shows a test set-up at TUDelft for the polyurethane variant. In addition to theeuropean railway review84
finalEsveld Slabtrack.qxd23/5/0310:08 amPage 5low noise and vibration nuisance the major advantage is short construction time. After the completionof a large testing program at TU Delft, an in situ testat HTM The Hague is envisaged later in 2003.OutlookFrom a point of availability and life cycle management the application of slab track may be expectedto grow. Efficiency of constructing will play anessential role. In this respect slipform paving seemsto have obvious advantages. On subgrades slabs witha bending resistance are potentially more cost-effective. Further studies to the effects due to subgradesettlements would be necessary to further optimisethe slab soil interaction. References[1] Esveld, C. (1999) Slab Track: A competitive solution. Rail International, Schienen der Welt, June1999.[2] Esveld, C. (2001) Modern Railway Track. MRTProductions, Zaltbommel. ISBN 90-800324-3-3(www.eseld.com)[3] Zwarthoed, J.M. (2001) Slab Track design:Flexural Stiffness Versus Soil Improvement.Proceedings of Rail-Tech Europe 2001 Conference.[4] Esveld, C., Kok, A.W.M. (1998) Interactionbetween Moving Vehicles and Railway Track atHigh Speed. Rail Engineering International, 27, 3,14-16.[5] Markine, V.L. (1999) Optimization of the DynamicBehaviour of Mechanical Systems. PhD Thesis, TUDelft. Shaker Publishing B.V. ISBN 90-423-0069-8.[6] Markine, V.L., J.M. Zwarthoed, C. Esveld, (2001)Use Of Numerical Optimisation In Railway SlabTrack Design. In. O.M. Querin (Ed.): EngineeringDesign Optimization Product and ProcessImprovement. Proceedings of the 3rd ASMO UK /ISSMO conference, Harrogate, North Yorkshire,UK, 9th -10th July 2001. ISBN: 0-85316-219-0(for text version), ISBN: 0-85316-222-0 (for CDROM version).[7] Bachmann, H., W. Mohr and M. Kowalski (2003)The Rheda 2000 ballastless track system. EuropeanRailway Review, Issue 1, 2003, 44-51.[8] de Man, A.P. (2002) DYNATRACK: Dynamicbehaviour of railway track. Delft University Press,Delft. ISBN 90-407-2355-9. (www.rail.tudelft.nl)[9] Penny, Ch. (2003) Balfour Beatty embedded tracksystem. Proceedings of Rail-Tech Europe 2003Conference.[10] Huurman, M., Markine, V.L., de Man, A.P.(2002) Design Calculations For Embedded Rail InAsphalt. Proceedings of Rail. Proceedings ofRailway Engineering-2002 Conference, London,UK, 3rd-4th July 2002. ISBN 0-947644-49-0.
Recent developments in slab track Coenraad Esveld,Professor of Railway Engineering, Delft University of Technology Delft With the design of railway lines factors like life cycle cost, construction time, availability and durability play an increasingly important role. In this respect, non-ballasted track concepts offer good opportunities.
May 27, 2016 · Two Way Beam Supported Slab References: 1. Design of. Reinforced Concrete, 2014, 9th Edition, ACI 318-11 Code Edition, by . Grid or Waffle slab One way slab Two way slab . 2 . 3 Figure: Two way slab (a) Bending of center strip, (b) grid model . Example: The two-way slab shown in Figure below has been assumed to have a thickness of 7
(structural 1997) and ECP 203 ‘Egyptian code (2007)’ allow the ribbed slab to be analyzed in accordance with the rules for solid slab or as the plain flat slab. In the analysis of ribbed slab as solid slab "traditional', the structural system of the ribs is considered as beams supported on main cross beams which are considered as rigid .
Figure 2 – Japanese Type RA Slab Track on Grade (Ref. 4) scale installations were made of this type of track because of concerns with excessive settlements. A current version of the slab track for at-grade application, referred to as the reinforced concrete roadbed system (
Element Design & Detailing Three elements of retaining wall: Stem, Toe slab & Heel slab are designed as cantilever slab Stem: Designed to resist moment caused by force f H k ( f load combination 1) Toe Slab: Net pressure is obtained by deducting the weight of concrete in the toe slab from upward acting soil pressure
standard receptor slab edge cover details standard receptor slab edge covers (1" (25.4) infill shown, 1-3/16" (30.2) similar) standard receptor with 7" (177.8) slab cover interior installed (8" (203.2) slab cover similar) variable slab egde cover standard receptor with acm panel or spandrel glass interior installed 2-piece sill receptor 2-piece .
Loads: Generally, the slab edges do not need to be thickened. However, multiple slab situations, or, for slabs more than 80m long, typically the slab edge is thicker than the slab by a factor of 1.4. The width of the thick edge is typically 800mm and slopes up to the slab depth at 1 in 10.
Recent Developments A Taste of My Research Representation of a Separable Preorder Framework and Information Two (or Three) Fundamental Principles A Theorem Outline Motivation Historical Background Early History Late 20th Century Consensus Recent Developments Developments within framework Multiple Dimensions of Poverty Time: Chronic and .
Safety Code for Elevators and Escalators, ASME A17.1-2013, as amended in this ordinance and Appendices A through D, F through J, L, M and P through V. Exceptions: 1.1. ASME A17.1 Sections 5.4, 5.5, 5.10 ((and)) , 5.11, and 5.12 are not adopted. 1.2. ASME A17.1 Section 1.2.1, Purpose, is not adopted. 2015 SEATTLE BUILDING CODE 639 . ELEVATORS AND CONVEYING SYSTEMS . 2. Safety Standard for .
