Embed Size (px)
Citation preview
CE-363
Lecture 13: Alignment of Track -
Profile
Dr. Ankit Gupta, Assistant Professor
Department of Civil Engineering
National Institute of Technology Hamirpur
Lecture Outline
Alignment of Track
Need
Requirements
Selection of Profile
Alignment
Types:
Horizontal Alignment
Vertical Alignment
Design Elements
Horizontal Profile
Circular Curves
Super elevation
Transition Curves
Widening of track
Track and Platform Clearances
Design Elements
Vertical Profile
Gradients
Grade compensation
Vertical curves
Speed on track
Alignment
Need - To
Ensure smooth and safe running of trains
Achieve maximum speeds
Carry heavy axle loads
Avoid accidents and derailments
Lesser maintenance efforts
Provide aesthetic value
Alignment – Basic Requirements
Purpose of new line
Integrated development
Shortest route
Maximum safety and comfort
Aesthetics
Alignment – Basic Requirements
Economic consideration
Minimum construction and maintenance cost
Minimum operational cost
Alignment - Selection
Choice of Gauge
Obligatory points
Important cities
Major bridges/crossings
Passes or saddles, tunnel sites
Religious places
Costly and problematic land, etc.
Alignment - Selection
Alignment - Selection
Traffic
Catchments area
15 km on either side; later expands to 25 km
Nature of traffic
Freight / Passenger
Volume of traffic
~ square of population
Traffic growth factors
Alignment - Selection
Geometric Standards – Most economical
combination
Locomotive performance
Gradient (Ruling) and Radius (Max.)
Affect weight / length of train
Min. 36 m long chord between two reverse
curves
Alignment - Selection
Geometric Standards – Most economical
combination
Straight portion near stations, bridges
Rise and fall
Hauling distance
Transition curves, vertical curves, etc.
Permissible limits
Alignment - Selection
Topography of the country
Plane alignment
Flat terrain, no problems
Valley alignment
Control points lie in the same valley
uniform gradient
straight line connectivity
Alignment - Selection
Topography of the country
Cross country alignment
Crosses water sheds of two or more streams;
sags and summits in succession
Mountain alignment
Alignment is increased in distance so as to limit
gradient up to ruling gradient
Length Development process is used
Alignment – Selection contd.
Mountain Alignment – Length development
Zig - zag development
Half circle loop (Horse shoe pattern)
Returns back upon itself
Follow side valleys or round the hill side
Alignment – Selection contd.
Alignment – Selection contd.
Mountain Alignment - Length development
Switch back development
For very steep side slopes
Uses switches and buffer stops
Reversal of direction
Alignment – Selection contd.
Switch Buffer Stop
Alignment – Selection contd.
Alignment – Selection contd.
Mountain Alignment
Spirals or complete loop development
Complete loop formed as bridge spiral or tunnel
spiral
Alignment – Selection contd.
Mountain Alignment
Alignment – Selection contd.
Mountain Alignment
Alignment – Selection contd.
Alignment – Selection contd.
Alignment – Selection contd.
Alignment – Selection contd.
Alignment – Selection contd.
Position of roads and road crossings
Political consideration
Geological Formations Good soil
Free of drainage problem
Rocky is stable but costly from construction point
Free of slips and slides
Alignment – Selection contd.
Effect of flood and climate Water logging
Snowfall
wind direction; sun facing locations
Cost consideration
Construction cost
quarry location, height, labour availability
Operating cost
Alignment – Selection contd.
Economic consideration
Maximum annual returns (r)
= (Revenue – Expenses) / Investment
