Airport 697
Runway Design 3
Caster angle is the angle formed between the tangent to the centre line
and longitudinal axis of the Aircraft.
As per ICAO, all the marking of runway are white, taxiway – yellow,
runway lighting colour-white, Taxiway lighting colour-Blue.
Runway orientation: It is oriented such that the direction of wind in
opposite to the direction of landing & take off.
Runway is so oriented that Landing and take off is done by Heading into
the wind (opposite to wind direction).
Cross-wind component:
V sin q = Cross wind component
it interupt safe landing & take off operation.
Type of aircraft Permissible limit of
cross wind component
Small aircraft 15 kmph
Mixed traffic 25 kmph
Big aircraft 35 kmph
Wind Coverage: The percentage of time in a year during which cross
wind component is within the permissible limits. (As above).
Wind rose diagram: It is the graphical representation of direction
duration & intensity of wind. it is use for orientation of runway.
698 Civil Booster (Civil Ki Goli Publication 9255624029)
The wind data of direction, duration and Intensity should be collected
from the wind Rose diagram over atleast 5 years & preferably 10
years is needed for airport designing.
Best direction of runway is usually along the direction of longest line
on wind rose Diagram.
Special Point: Calm period is the percentage of time during which
intensity is less than 6.4 kmph
Basic Ruway length
Length of runway under following assumed conditions
(i) Airport at sea level
(ii) Enroute temperature is standard.
(iii) Runway is levelled in longitudinal direction.
(iv) No wind blowing on runway.
(v) Temperature of airport is 15ºC (standard)
(vi) There is no wind blowing enroute to destination
(vii) Aircraft is loaded at its full capacity.
Corrections in runway length
According to ICAO, (Basic Runway length should increase at rate of
7% per 300 m rise in elevation from MSL.
According to ICAO, Basic runway length after has been corrected for
Elevation, should further increase by 1% for 1c rise in Airport reference
Temp above the standard atmosphere temperature at that elevation.
Special Point: If above combine correction exceed 35% of BRL, then
there correction should be further check by specific study at the site by
Modal tests.
FAA recommended the correction (After corrected temperature &
Elevation correction), BRL should increased by rate of 20% for Every
1% in effective gradient.
ICAO does not recommend any gradient correction
Geometric design of Runway
(i) Runway width: Recommended range is 18 m to 45 m. Typical aircraft
traffic is concentrated at central 24 m.
(ii) Runway length: Actual runway length (L3) depends upon elevation,
temperature & gradient.
704 Civil Booster (Civil Ki Goli Publication 9255624029)
Tunnel Engineering 17
It is an engineering structure, artificial gallery, passage or roadway beneath
the ground, under the bed of a stream or through a hill or mountain.
Open cuts:
It is open to sky passage excavated through huge soil mass of obstacle
like hill, run in required direction to connect.
Open cuts are provided up to depth 18m economically, if more than
18m depth.Tunneling is preferred. (60 feet)
For highways, tunneling is preferred to open cut if the depth of open
cut exceeds 15m.
It will require less time & cost for construction as compared to tunnels.
Advantages of tunnel
(a) For carrying public utilities like water, gas, railway lines or roads etc.
(b) Lesser maintenance &operating cost.
(c) Aerial warfare & bombing of cities have given important values to
tunnel.
(d) Cost of hauling is decreased due to lighter grades, possible in tunnels.
Classification
Purpose Type of construction Position or
material Alignment
Traffic Conveyance Tunnel in Saddle or
hard Rock Base tunnel
Railway Hydro Electric Tunnel in Quick Off spur tunnel
power tunnel Sand or loose sand Spiral tunnel
Pedestrain
Sewer tunnel Open cut tunnel Slope tunnel
Highway
Water supply
tunnel
Tunnel Engineering 705
According to Alignment
(a) OFF - Spur Tunnels
Short length tunnels to negotiate minor local obstacles, is very
high projections on the way, which cannot be followed with
permitted
(b) Slope Tunnels:
Tunnel constructed in sleep hills for economic and safe opera-
tions of roads and railways.
(c) Saddle or Base Tunnels:-
Tunnel constructed in the valleys along the natural slope till slope
does not exceed ruling gradient
(d) Spiral Tunnels:
Tunnel provided in narrow valley in the form of loops in the inte-
rior of mountain so as to increase length of tunnel to avoid steep
sloper
Shape of the tunnel
D-Section or Rectangular Circular Egg-Shaped Horse-Shoe
Segmental roof
5D
D 2D
1 .2
D 2D
1.2
5D
D D D
1 in 24 1 in 24 D D
(a) ‘D’ Section (b) Rectangular © Circular (d) Egg. Shaped (e) Horse-shoe
Section Section section section
(i) In Rock tunnels: It is suitable for subway/Navigation channel.
(ii) Egg shaped section is used in sewers as it maintains required self
cleansing velocity. It provide least crosectional area at bottom.
(iii) Rectangular section is suitable only in case of hard rocks.
(iv) Circular section: It is most suitable for sewer & water carriage. It
is best suited for materials without cohsion (Quick sands) where the
pressure acts normal to the line of profile.
(v) Horse shoe shape is best suited for traffic purposes. It is most popular
for tunnel.
It is suitable for soft rock but difficult to construct.
706 Civil Booster (Civil Ki Goli Publication 9255624029)
Investigations in tunnel construction
Information collected are
(i) Origin of soil mass.
(ii) Location of faults, folds etc.
(iii) Temperature of soil near by.
(iv) Hydrology in surrounding proposed tunnel site.
(v) Presence or foul gases.
(vi) Bearing capacity of soil mass at proposed site.
Sequence of operation
(a) Locating centre line on ground.
(b) From centre line to inside tunnel.
(c) For required grade at the bottom of tunnel.
(d) Checking tunnel cross-section.
Grades in tunnels
Grades in tunnel should be lesser than surface grade.
It is not favorable to continue tunnel approach grades in tunnel especially
in railway.
For Tunnels > 300m length, grade should be provided below 75% of the
ruling gradient.
In order to maintain desired shape of tunnel the C/S must be check at
regular 2m to 3m interval.
Setting of centre line
Curve linear tunnel Long tunnels Short tunnels
(a) method of tangent offsets By triangulation using Theodolite with
(b) method of chords & micrometer & wooden stakes
deflection angles transit theodolite
Setting out is defined as marking the centre line or alignment of any
construction work on ground.
It is done indirectly in different stages using theodolites.
Modern way of providing horizontal control on ground surface is by
running an open traverse between two ends of proposed tunnel by
using theodolite of precision and laser unit pole.
Bridge Engineering 717
Bridge Engineering 18
Codes used for Bridge Design:
1. IRC - 5 - Code of practice for specification of Bridge.
2. IRC - 6 - 2010 - Loads & stress. (L.S.M.)
(Old Code - IRC - 6 - 2000 - (W.S.M.)
3. IRC - 21 - Code of practice for cement concrete (L.S.M)
4. IRC - 22 - for composite structure
5. IRC - 78 - for foundation design
Bridge is an arrangement made to cross an obstacle in the form of a
low ground or a stream or a river or over a gap without closing the
way beneath.
Required for the passage of railways, roadways footpaths and even
for carriage of fluids.
Components of bridge
1. Sub-Structure
Component of bridge upto the level of bearing.
Consists of piers, abutments, wing walls and foundations for the piers,
abutments and wing walls.
2. Super Structure:
Component above the level of bearing.
Consist of beams, girders, arches and cables, parapet walls. Flooring,
guard stones, hand rails etc.
3. Adjoining Structure:
Component like approaches, guard stones, bearing, river training work,
apron etc.
718 Civil Booster (Civil Ki Goli Publication 9255624029)
Water way
Parapet or Crash Barrier
Bridge Deck
ch
oa
pr l1
Ap Bearing l2 l3
free
board
HFL Pier
Abutment BED LEVEL
Pile cap Scour depth Abutment
Array
Wall Pile
Bearing
R.C.C.
Pier cap
Pedestol
Linear waterway = Pier
l1 l2 l3
Pile cap
Pile
Classification of Bridge
1. According to span
(i) Culvert
(ii) Minor Bridge
(iii) Major Bridgeiv) Long span bridge
2. According to Masonary
(i) Timber
(ii) Masonary
(iii) Iron & Steeliv) Prestressed
3. According to loading I.)Class A ii.) 70 R loading
Permanent Bridges
iii.)Class AA iv.)Class B
Temporary Bridge
Bridge Engineering 727
Some Important Formulae:
1. Marriman's formula:
V2 A 2 A
ha
2g Ca A1
2. Molesworth formula:
V2 A 2
ha 0.015 1
17g Ca
Where, A = Natural Waterway, A1 = Linear Waterway
Ca = Contracted Area
CIVIL Ki GOLI
Inglis Khosla
Dicken
DRINK (formula for Discharge of River)
Ryne Nawab Jung Bahadur
Constant
1. Dicken's formula: Q CA3/4 Area of catchment
This formula is applicable in North India
2. Ravey's formula: Q CA 2 / 3
Applicable in South India
3. Ingli's formula : Q 123.2 A
Applicable in Maharashtra Region
123.2 A
4. Nawab Jung Bahadur's formula : Q
A 10.36
Applicable in North & South India
