Track Design For Line Speed Improvement - Case Study Example

May 14, 2009 Track Design for Line speed Improvement Introduction Railway design takes careful consideration requiring the route, alignment, track structure. materials, turnout, track maintenance and management, track repair and standard and railroad maintenance operations. In the study request, the line speed over a section of a track that is 50 kilometres long is to be improved. The route is a twin track that is joined with its traffic that is to serve a conventional passenger train running at 150 kilometres per hour and a freight train at 100 kilometres per hour seed.. The improvement is to run along the 50 kilometres track. The route has several sections of sharp radii curves and steep vertical gradients. There are also several stations , tunnels and a number of bridges that are present. The line has a power supply for traction trough an overhead line electrification system. The new traffic flow also requires traffic with a heavier axle weight to run that would increase from 20 tonnes to 25 tonnes. With the new traffic flow, tilting trains as well as conventional passenger stopping train will be non stop. The proposal also include the design of a transition curve. The transition curve will run along a straight tract to a curved track and vice versa. The transition curve will allow the trains to shift from one track to the other. The access of the main lines will be required at a minimum speed of 50 kilometres per hour, and about 50 trains are expected to use the track everyday. It is also in the proposal that a new turnout for a freight depot is to be constructed. Route Surveying for condition The steps and procedures of the track laying and inspection of the survey are the same. Different trackwork may vary with different approaches. With the definition of route surveying, it is composed of all survey operations necessary for the design and construction of engineering works such as railroads. It is associated with the different highway design and construction. In relation with the design of the new transition curve that we are studying for improvement, route surveying will include the review if the existing track curvatures both horizontally and vertically. In the reconnaissance and planning stage, the discussion with the incumbent engineers of the present situation of the railroad tracks must be considered. This is very important because the engineers will be able to inform us about the situation of the railroad track, and therefore we can include in our report the present situation of the tracks. We can gather data from the incumbent engineer so that we would know what design we should do because we were informed about them. Moreover, we would know how to go about all the problems we will be incurring in the design. We must also review the track geometry information for the route. From the result of all the data gathering that we did, we can finally pinpoint where the problems are and what are the underlying causes of the problems. We can now make our design of the track based from the findings that we have gathered. The designs for the improvement are then worked on for implementation. Transportation infrastructure, and other major projects are often required of taking of real property, or right of way. The cost of partial takings, commercial properties remainder damages, court costs, utility relocation and other right of way related items are difficult to anticipate. The accurate estimation procedure are needed to facilitate budgeting and timely completion of projects. The construction of works is termed as the actual implementation of all the processes which takes from reconnaissance and planning. Talking with the incumbent track management or the engineer will be of great help. We will be able to know where the impact of forces that are currently generated by the existing traffic are. There could be problems in the track that are not visible, but can be observed by the daily activity of the railroad users. Problems could be that there maybe rail sidewear, crushed pads under the track, track regularly going out of alignment because of horizontal forces or tracks moving longitudinally down steep vertical sections. These are some of the problems that must be given considerations in the improvement of the track. Components required for the route improvement In the route improvement of railroad tracks, there are certain stages that we follow. Stationing uses the centreline of the railroad for reference points. These are stations which are marked at 20 meters apart chord in curved track and at the valuation point. Stations are assigned in the route in order to determine locations and results of the surveying that was performed. The results are very important in the sense that there could be some sort of obstruction in the actual implementation of the improvement processes. The offset distance is the specified line of curve. This is an implementation of the pair of 2 lines or curves with equal distance from the point of the original curve or line. The vertical alignment is called the profile grade required to all roadway or computation of the track design. The specifics in the design is provided by its vertical alignment data. Vertical curves are required at intersections of different road/rail gradients. Railroad gradients are to be included in the design because of the rate of change in the vertical acceleration is to be gradual for the safety and comfort of the commuters and the visibility of the incoming vehicles for safe distance. Horizontal curves are those curves that change the alignment The offset stakes are used to catch points and produce a slope stake information. The location is dependent to the position of the pivot point where the slope will begin, The slope stakes are used in railroad tracks for locating the toe of the slope or the top of the cut. The dispute between he economic and environmental aspect for the network is supported by government agencies, thus addressing the "Delivering a Sustainable Railway"(Verslype, 2008). The sustainable improvement of a railway system can be achieved. The railway staff and management takes care of the improvement of the track construction, transportation, mechanical processes and electrical matters. The design requirement of the route is considered with the materials, turnout, track structure and maintenance management, together with the track repair standard and railroad maintenance operations. Identification of the Current and Likely Effect of Rail Forces On Route There are speed restrictions imposed because of the very poor condition of the track components and formation/drainage problem. These problems must be included in the improvement proposal. The rehabilitation of these sites can be done, using geogrids or similar materials and the drainage works should also be considered. Problems concerning drainage could be dangerous. It could derail a speeding train. The improvement will forecast for more accommodations of commuters. Other reasons for the speed limitation is the stiffness formation. Again, the stiffness formation is coupled with drainage problems. There must be a regular clean up along the route so that there sill be no stiffness formation thus, having well maintained railroad tracks means safer travel of commuters. Consideration of Formation, Drainage and Ballast The high density rainfall will result in the drainage problem of the track and the ballast's quality deterioration. The slope of the earthwork is often affected by the rainfall. Problem arises the moment the formation becomes soft. Another cause is the sudden stiffness of the formation. An example of stiffness problem is the formation that is at the interface of a normal ballasted track under bridges. The improvement of the drainage system is just a partial solution to the stiffening of the ballast. This is normally done to cope up with the loads. Another partial solution is the regular maintenance for the stiffening ballasts. The Department of Transportation, with the review done, revealed that the challenge for the railway industry will be the reduction in the travel time. The Railway Safety and Standards Board (RSSB) published in 2003, stated that the effect of climate change in the railways are the following. Change in temperature affects the track and the extreme precipitation affects the earthworks. Overhead line equipments are affected by the extreme wind and the drainage system is affected by the precipitation. Professor Alec Skempton published in his paper, , the subject in the 1950's and in the 60's the culmination (geotechnique, vol.20, September, 1970) of the mechanism of the failure are now clear. The earthwork and the drainage infrastructure are the mostly affected. The infiltration of water into the cracks that are formed in the soil on dry season normally speeds up the stability of the slopes. There are unknown factors of mechanism that persist in railway embankment with the level of comparison used in the installation of the geological materials in the embankment. The toe crest drainage system in the earthwork area with a herringbone slope drains clearly and has a vital role in the slopes stability. Sometimes, animal burrowing undermines the sustainability of the railway in the soil. The vegetation is also a factor due to its assistance to the slope stability through a combination of reduced water content and the reinforcement of the roots. In consideration to these factors, the railway system is undergoing inspections of the earthworks. Curved Track Requirements There are requirements in the construction of railroad tracks. In the transition length for higher speed, the slope is a requirement for the gauge, alignment and surface of track, which includes the elevation of the outer rails and the speed limitation. This is measured between the heads of the rails at 90 with its rails in the plane 5/8 inch below the top of the rail. Its alignment does not deviate from the uniformity of more than the amount prescribed and the end of the line must be at a point in the gauge of the line trail. The outside rail of the curve may not be lower than the inside rail, and the maximum allowable operation speed for the curve is determined by the formula Vmax = where: Vmax = Maximum allowable operating speed (miles per hour) Ea = Actual elevation of the outside rail (inches) d = Degree of curvature (degrees) The elevation of curved track run-off is defined as "if the curve is elevated, the elevation is provided through out the curve unless physical conditions does not permit. If the elevation run-off occurs in a curve, the minimum elevation is to be in the computation of the maximum allowable operating speed for the curve. The elevation run-off must be of constant rate within in the limit of the railroad track surface deviation. It is to be extended at full length of the spirals. The track surface applies to maintain the surface of the track within the limits prescribed. Interpolation of speed between the track classes means that in the event that the track geometry defect is detected in the inspection of cars, the railway can use interpolation in determining the speed of the temporary slow order for the protection of the defect. Switch and Crossing Design A railroad switch, point or turnout are mechanical installations that will enable the railway trains to be guided from one track to another at railway junctions. The figure will illustrate how the train will transfer from one track to the other. Transfer of the trains from one tract to the other is indicated by the double ended arrow heads, The design of the track is such that a train running at a minimum speed 50 kilometres per hour will cross the track without slipping out of the track. The track was designed to cover the speed of the train. The design of the first converging track is on the straight track and the other one is converging track on the curved track. IN the analysis, the design of the second converging track is that the horizontal curve is converging with a combination of a reverse horizontal curve. The switch is a pair of linked rails known as the points (switch rails or point blades) that are between the diverging outer rails. These points are movable. They can be moved from one of the two positions in order to determine the direction of the train coming from either ends of the tracks. A switch has a straight through track and a diverging route. Right hand switches have a diverging path to the right of a straight track and when it is coming from a narrow end and a diverging track ;leaves, going to the opposite side. A straight track may not be at all times present. There could be times that both tracks could curve on the opposite sides of both tracks may even curve with a different radius, all in the same path. Designing a railroad track that will cater to more trains and an increased weight of freight. The materials to be used in the construction of the track must also increase its load design. The design load of the materials to be used can be computed in reference to the load bearing capacity of the steel track to be used. The steel to be used must be harder with higher bearing capacity to be sure that the steel material used in the track will not buckle in the event that a heavy weight of freight is to pass thru the track. Clearances The overhead clearance is the perpendicular distance from the top of the highest rail and the lowest point of an overhead structure or obstruction. The side clearance is the shortest distance from the centreline of the track and the structure or any other obstruction such as ladders, downspout piles of materials, equipments and other. The use of the overhead clearance is for transporting of conventional railroad cars. It is approximately 8.5 metres long or otherwise provided. The minimum clearance inside a building is 7.0 meters. The minimum clearance from the centreline of a curved railroad track is 1"/30 minutes of a curvature that is to be added to the side clearance from thecentreline. The side clearance should be at 8 feet fro structures and obstructions above the top of the rail. With the improved track system, and with the new and better trains, the new trains will have new and different swept envelopes as they pass through the route. The gauging exercise will determine the envelopes of the new trains. For the gauging of the new swept envelop, The trains will have to undergo the gauging process to determine whether there would be problems that will arise from the new and improved design of the track. Track Renewal Methodologies and their varying Effeciencies Optimizing maintenance deals with the renewal of track that is linked with the track monitoring. Optimized cost maintenance area achieved by the strategies that are placed in suit of the needs. Means of technically establishing accuracy on the possible extent of the maintenance of the tracks are available. The options, procurements of materials with the adoption of QA program will be included in the research maintenance. Optimal monitoring study of rail wear and fatigue condition of track, including the new innovative methods, sensors and systems are included in the study. Maintenance technique of rail in the optimal track maintenance include grinding, lubrication, recharging in curves and the replacement of rail. The aim is to have the innovative track renewal methods which are faster than the classical methods for the tracks. The fixing of rails in curves and for special track works, that is to extend the normal life with the least review of existing strategies for the maintenance. Reducing the costs buy at least 20% with the combination of the improved quality and performance of the establishment of a standard track maintenance. The maintenance is extended with the qualified effect on the LCC, comfort and safety. The maintenance strategy of the existing tracks with the procurement of components and control of impact that will destroy the monitoring and the maintenance technique of the preventive and predicted schemes Possession Regime for Works The overall time of possession are set by the infrastructure manager. It is mainly based on the overall financial benefits to all the stake holders of the railway. When the contractor has to work on certain jobs orders, the infrastructure manager can suspend the operations of the railways to give way to the work , or improvement or clean up of the drainage system of the railroad track. If the work to be performed s vey urgent, there is a commitment of the infrastructure manager to suspend whatever activities the railway is undergoing top give way to the construction or improvement in the railroad track. Interfaces with other Engineering Functions (e.g. track/overhead) In track signaling interfaces, fast trains are to require the synchronization of the signaling and track system to the higher speed. These would mean the adjustment of isolated joints with in the track premise and the signals be moved to other places. Station based systems and line control systems interface with one another. In heavy rails, which are already upgraded, railway system connects to existing lines are constructed with other forms of technology. The possession and isolation which is effective and efficient, the inter-operational activity between the old and the new will be critical. The train will run smoothly and safely without interruptions across the interfaces. Cost and disruption is encurred in the networks when the control rooms does not function correctly. The design of railway control centre interfaces can have better designs for the inter-operations, and for the management of as efficient, safer and improved train to be on the go. Required Transition Design The transition design involves the horizontal curve and the vertical curve. The analysis of the transition design in the adjacent tracks takes a stretch of 50 kilometers. The curves are composed of reversed curves having two different radius connecting to a straight track. When horizontal adjustment of the track centre is conducted according to the track centre setting outcome, based on direct leveling elevation the track surface elevation is positioned to the designed level through the vertical adjustment board. For the curved section, another steel track is required for cant construction, Repetitions are required until the track center position and the track surface elevation complies with the design criterion. Comprehensive inspection determines that the gauge, either horizontal or vertical alignment direction and twist are in compliance with the standards, the hardware structure of the track has been completed. The analysis of the design of the converging horizontal curves and the design of the railroad track depends greatly on the capacity of the railroad track to carry. The conditions in the design of the railroad track is to carry 50 passenger trains per day and the freight is assumed to carry twice as much load as the passenger train, it will be designed for the load it will be able to carry. The design is to consider the present existence several stations a number of bridges and tunnels. The slope vertical gradient are covered under the vertical curve design and the sharp curves are under the horizontal curve design. The railway design will have a traffic flow that will have a heavy axle weight in order to run with the increased load of 20 to 25 tonnes daily. Selected Turnout Design for the New Freight Facility. The turnout design of the new railroad track will carry moving loads equal to 20 tonnes to 25 tonnes daily. This will generate bigger income for the railways administration and this will ease the volume of traffic in highways. With proper planning and implementation of the merging of the adjacent twin railroad track, will prove that travelling will be safer and more comfortable Inspection Items Ballast Section Non-Ballast Section Gauge () 1-3 0-3 Cant/Cross Level () 4 2 Vertical Alignment (/10m) 4 2 Horizontal Alignment (/10m) 4 2 Twist ( /5m)(not including cant 4 4 Conclusion The design of the improvement of the railroad track is very beneficial to the commuters as well as the freight services. The design transition of the twin railroad tracks are more advantageous to the commuters. Track designs involves not only the knowledge of horizontal curve designs, but also the different factors that affect the design of the railroad track. Redesigning a track while giving consideration to other factors is challenging. The improvement of the track will be very beneficial to management of the railways, the commuters as as well as the freight services of the area. The implementation of the design transition of the two adjacent railroads will have better services than before. The commuters will be having shorter travel time with safer trains to ride on and to have a more comfortable travel. ON the other hand, the freight train will be able to transport more goods with better handling and shorter time to reach the destinations. References Baggott, Martin, Towards Efficient Transportation Networks, On The Right Track, May 2007,GHDNewsletter,May 2, 2009. http://www.ghd.com.au/Rail_Enewsletter/article 1.htm. Davis, Foote, and Kelly, 2004, Surveying, Kogakusha Company,LTD. Tokyo FHWA,2003."Acquisitionforthe90's."URL: http://www.fhwa.dot.gov/realestate/acq90s.pdf (accessed on May 2, 2009) Skempton, Alec (geotechnique, Vol. 20, September 1970) http://www.fabermaunsell.com/media/5236.pdf Specific Authority 351.35(1) FS. Law Implemented 341.302(7), (8), 351.35(1), (2) FS. History-New 1-27-81, Formerly 14-57.03, Amended 7-27-97, 10-16-01 Surveying and Mapping, Surveying. 1999. PHD.com Publications. May 3,2009 http://www.pdhcenter.com/courses/l108/108content.pdf Verslype, Marcel, Executive Director, European Railway Agency http://www.publicserviceevents.co.uk/ppt/ri08_marcel_verslype.pdf http://www.extranet.vdot.state.va.us/loades/IgrdsManuals/concept/APP_D./pdf http://www.tpub.com/inteng/11.htm http://update.carlsonsw.com/docu/survce/survCE_Help.htmlslopestaking http://en.wikipedia.org/wiki/railroad_switch Davis, Foote, and Kelly, 2004, Surveying, Kogakusha Company,LTD. Tokyo FHWA,2003."Acquisitionforthe90's."URL: http://www.fhwa.dot.gov/realestate/acq90s.pdf (accessed on May 2, 2009) Read More