Highway Design - Techniques for proper Planning and Execution .

Continues Improvement Is Better Than
Delayed Perfection
- Mark Twain

• To have a Reliable Infrastructure.
• To have a Green Infrastructure.
• To have a Smart And Safe Infrastructure.
• To have a Human Infrastructure.

• Lifetime engineering
• Fast, hindrance-free maintenance
• Balancing demand and capacity
• Asset management tools

• Saving natural resources
• Emission Control

• Safe design
• Smart design
• Smart communication
• Smart monitoring

• Public security
• Multi-functional use
• Human design

• Highway Location Survey.
• Highway Alignment Survey
• Highway Traffic Survey
• Highway Geotechnical Investigation Survey

• Map study
• Reconnaissance
• Preliminary surveys
• Final location and detailed surveys

• Setting out alignment on ground.
• Taking cross-sections to full right of way at
fixed interval.

• Classified traffic in terms of Car, Two Wheeler,
Three wheeler, Trucks, MAV, Bus, Mini bus, LCV,
Cycle, Animal driven vehicles, cart, etc. are
counted 24/7 on project highway and Average
daily traffic is calculated.
• Traffic varies on road by season, month, week,
week-days, hours.
• Seasonal variation factor is use to convert ADT
to AADT.

• Trail pits / Bore Holes are taken at fixed
interval on projected road.
• Soil samples are tested to know the engineering
properties of soil.
(a) Gradation
(b) Atterber’s limit
(c) Free swelling Index
(d) CBR

• DGPS ( Differential Global Positioning System).
• Total Station.
• Video Graphic Vehicle count .
• Ground Penitrating Radar

• Design vehicles are selected motor
vehicles with the weight, dimensions, and
operating characteristics used to
establish highway design controls for
accommodating vehicles of designated
classes.
• For purposes of geometric design, each
design vehicle has larger physical
dimensions and a larger minimum turning
radius than most vehicles in its class.

Dimension
of vehicle
Details Maximum Dimension (m)
(Excluding front and
rear bumper)
• Width All Vehicles. 2.50
• Height (a) Single-Decked vehicle for normal
application .
3.80
(b) Double-decked Vehicle . 4.75
• Length (a) Single-unit truck with two or more
axles. (type 2,3)
11.00
(b) Single-unit bus with two or more
axles. (type 2,3)
12.00
(c) Semi- Trailer tractor combinations
(type 2-s1, 2-s2, 3-s1, 3-s2)
16.00
(d) Tractor and Trailer combinations
(type 2-2, 3-2, 2-3, 3-3)
18.00

• The choice of design vehicle is influenced by the
functional classification of a roadway, and by
the proportions of the various types and sizes
of vehicles expected to use the facility.
• On rural facilities, to accommodate truck
traffic, one of the semitrailer combination
trucks should be considered in design.
• In urban areas that are highly built-up,
intersections may be designed to provide fully
for passenger vehicles but require the larger
vehicles to swing wide upon turning
• The vehicle which occurs with
considerable frequency is often selected
as the design vehicle.
• The largest of all the several design
vehicles are usually accommodated in the
design of freeways, subject to state laws
on permitted vehicles.

• The speed with which vehicles travel on
the road is seldom the maximum speed the
vehicle is capable.
• Choice of design speed depends on the
function of the road as also terrain
conditions. Terrain is classified by the
general slope of the country across the
highway alignment.
S. NO. Terrain classification
Per cent cross
slope of the
country
1 Plain 00-10
2 Rolling 10-25
3 Mountainous 25-60
4 Steep <60

SR.
NO.
Road
Classificati
on
Design Speed (in KMPH)
Plain Terrain Rolling Terrain Mountainous
Terrain
Steep Terrain
Ruling
Design
Speed
Minimu
m
Design
Speed
Ruling
Design
Speed
Minimu
m
Design
Speed
Ruling
Design
Speed
Minimu
m
Design
Speed
Ruling
Design
Speed
Minimu
m
Design
Speed
1 National And
State
Highway
100 80 80 65 50 40 40 30
2 Major
District Road
80 65 65 50 40 30 30 20
3 Other
District Road
65 50 50 40 30 25 25 20
4 Village Road 50 40 40 35 25 20 25 20

Tangent
Curve
Tangent to
Circular Curve
Tangent to
Spiral Curve to
Circular Curve

R = Radius of Circular Curve
PC = Point of Curvature
(or BC = Beginning of Curve )
PT = = Point of Tangency
(or EC= End of Curve )
PI = Point of Intersection
T = Tangent Length
(T = PI – BC = EC - PI)
L = Length of Curvature
(L = EC – BC)
M = Middle Ordinate
E = External Distance
C = Chord Length
Δ = Deflection Angle

Degree of Curvature
• Traditionally, the “steepness” of the
curvature is defined by either the radius
(R) or the degree of curvature (D)
• Degree of curvature = angle subtended
by an arc of length 100 feet
R = 5730 / D
(Degree of curvature is
not used with metric units
because D is defined
in terms of feet.)

Length of Curve
• For a given external angle (Δ), the length of curve
(L) is directly related to the radius (R)
L = (RΔπ) / 180
= RΔ / 57.3
R = Radius of Circular Curve
L = Length of Curvature
Δ = Deflection Angle
• In other words, the longer the curve, the larger
the radius of curvature

Other Formulas…
Tangent: T = R tan(Δ/2)
Chord: C = 2R sin(Δ/2)
Mid Ordinate: M = R – R cos(Δ/2)
External Distance: E = R sec(Δ/2) - R

• The amount by which the outer edge of a curve
on a road or railway is banked above the inner
edge.

Road Plan ViewRoad Section View
CL
2%2%

CL
2%1.5%

CL
2%1%

CL
2%0.5%

CL
2%-0.0%

CL
2%-0.5%

CL
2%-1%

-1.5%
CL
2%2%

2%-2%
CL

3%-3%
CL

4%-4%
CL

2%
CL
-1.5%

2%
CL
-1%

2%
CL
-0.5%

2%
CL
-0.0%

2%
CL
0.5%

2%
CL
1%

2%
CL
1.5%

2%
CL
2%

• Transition curves are provided in between a
straight road and the Curve of a design radius.
So the radius of a transition curve varies from
infinity to the design radius or vice verse. The
length of the transition curve must fulfill some
requirements. It is designed to fulfill the
following three conditions:
(a) Rate of change of centri-fugal Acceleration(C):
As per IRC recommendations, 𝐶 =
80
(75+𝑣)
𝑚/𝑠𝑒𝑐3
Here,
C= allowable rate of change of centrifugal
acceleration (0.5 < 𝐶 < 0.8 𝑚/𝑠𝑒𝑐3)
Ls= Length of the transition curve.
𝐿 𝑠 =
0.0215∗𝑉3
𝐶∗𝑅
(b) Rate of introduction of Designed super-elevation:
If pavement is rotated about center line, then
1/𝑁 = (𝐸/2)/𝐿𝑠
=> 𝐿𝑠 = 𝐸𝑁/2 = 𝑒. 𝐵. 𝑁/2 = 𝑒. (𝑊 + 𝑊𝑒). 𝑁/2
If pavement is rotated about inner edge, then
𝐼/𝑁 = 𝐸/𝐿𝑠
=> 𝐿𝑠 = 𝐸𝑁 = 𝑒. 𝐵. 𝑁 = 𝑒. (𝑊 + 𝑊𝑒). 𝑁
where, Ls= Length of transition curve
B= width of the pavement
(c) By Empirical Formula given by IRC(Indian Roads congress):
It should not be less than
(i) For plain and ruling terrain: 𝐿𝑠 = 2.7 𝑉^2/𝑅
(ii) For mountainous and steep terrain: 𝐿𝑠 = 𝑉^2/𝑅
Find out the greatest length of the transition curve by the above
three criteria and use to construct the transition curve.

• 𝑅 =
𝑉2
127×(𝑒+𝑓)
Where R = Radius in meter
V = Speed of vehicle in kmph
e = Rate of superelevation
f = Design value of lateral friction coefficient =
0.15
• e =
𝑉2
225×𝑅
Superelevation is provided 75%of design speed
Maximum superelevation 7% for plain and rolling
terrain and 10% for hilly and steep terrain

• Mechanical widening
• 𝑊𝑚 =
𝑛∗𝑙2
2∗𝑅
• Psychological widening
𝑊𝑝𝑠 =
𝑉
9.5∗ 𝑅
• Extra widening
𝑊𝑒 = 𝑊𝑚+𝑊𝑝𝑠

• Grade Compensation =
30+𝑅
𝑅
.
• Subjected to maximum value of
75
𝑅
.
• IRC recommends compensation is not necessary
for gradient flatter than 4%.
∝

Crest Curve
Sag Curve
G1
G2 G3

Radius Parabola
y  ax2
 bx  c
Horizontal Curve Vertical Curve

BVC
EVC
L
G
2
G
1
Change in grade: A = G2 - G1
where G is expressed as % (positive /, negative
)
For a crest curve, A is negative.
For a sag curve, A is positive.
L/2
L/2
PI

• Determine the minimum length (or
minimum K) for a given design speed.
– Sufficient sight distance
– Driver comfort
– Appearance

Crest Vertical Curve
• If sight distance requirements are satisfied then
safety, comfort, and appearance will not be a
problem.
h1 = height of driver’s
eyes, in ft.
h2 = height of
object, in ft.
• When L > SSD- 𝐿 =
𝑁𝑠2
4.4
• When L <SSD - 𝐿 = 2𝑆 −
4.4
𝑁

Sag Vertical Curve
• Stopping sight distance not an issue. What are the
criteria?
– Headlight sight distance
– Rider comfort
– Drainage
– Appearance
• When L > SSD - 𝐿 =
𝑁𝑆@
(1.5+0.035𝑆)
• When L < SSD - 𝐿 = 2𝑆 −
(1.5+0.035𝑆)
𝑁

• Temperature Stresses
– Due to the temperature differential between the top
and bottom of the slab, curling stresses (similar to
bending stresses) are induced at the bottom or top of
the slab
• Frictional stresses
– Due to the contraction of slab due to shrinkage or due
to drop in temperature tensile stresses are induced at
the middle portion of the slab
• Wheel Load Stresses
– CC slab is subjected to flexural stresses due to the
wheel loads

𝑙 =
4 𝐸ℎ3
12 ∗ 𝑘 ∗ 1 − 𝜇2
Type equation here.Where,
E = Modulus of Elasticity of concrete, MPa
h = thickness of slab, m
μ = Poisson’s ratio
k = modulus of subgrade reaction, MN/m3

–𝑆𝑓 =
𝛾𝑐 𝐿 𝑓𝑎
2

• The contraction joints are spaced to limit the
tensile stress induced in the slab to the value that
can be born by the slab during curing period
• Spacing is found out by taking the allowable tensile
stress as 80 kPa during curing period of concrete
𝐿 =
(2𝑆𝑓 )
(𝛾𝑐 𝑓𝑎)
• For 𝑆𝑓 = 80 kPa, 𝛾𝑐 = 24 kN/m3 and 𝑓𝑎= 1.5
L = 4.52 m
Therefore, the spacing of contraction joints is kept
as 4.5 m.

Slab Thickness
(cm)
Maximum Contraction
joint spacing (m)
15 4.5
20 4.5
25 4.5
30 5.0
35 5.0

• The loads causing failure of pavements are mostly
applied by single and tandem axles, stress must be
determined for the condition shown in chart’s given by
Picket &Ray for stress computation in the interior as well
as edge region
• Using fundamental concept of Westergaard and Picket
&Ray’s pioneering work a computer program IITRIGID
developed at IIT, Kharagpur was used for edge load
condition

• As per IRC 58-2011 stresses in Rigid pavement
by wheel load analyzed for following condition.
• (a) Bottom up Cracking
-By traffic 10.00 AM to 4.00 PM
• (b) Top Down Cracking
-By traffic 00.00 Am to 6.00 AM

• Fixed traffic
– Design is governed by single wheel load – Load
repetitions is not considered as a variable – Multiple
wheels are converted into single wheel – Heaviest wheel
load anticipated is used in design
• Variable traffic and variable vehicle (Spectrum of
Axles Approach)
– Both vehicle and traffic are considered independently.
i.e., treat all axles
separately and use spectrum of axles in the design

Fixed vehicle
– Design is governed by the number of repetitions
of standard vehicle or axle load, usually 80 kN
single axle load – Repetitions of non-standard
axles are converted into equivalent repetitions
of standard axle using equivalent axle load
factors
– The cumulative number of repetitions of
standard axle during the design life is termed as
Equivalent Single Wheel Load (ESAL) and is the
single traffic parameter for design purpose.

• Equivalent Single Axle Load is the equivalent
repetitions of standard axle during the design
life of the pavement.
• IRC terms this ESAL as cumulative number of
standard axles during the design life.
• The number of repetitions of different types of
axles are converted into equivalent repetitions
of standard axle by using Equivalent Axle Load
Factors (EALF).

• Approximate EALF can be worked out using the
fourth power rule
Single Axle Single wheel Load EALF = (Axle Load in
KN/65)^4
• Single Axle Dual wheel Load EALF = (Axle Load in
KN/80)^4
Tandem Axle Load EALF = (Axle load in KN/148)^4
However, as the EALF depends on axle load as wheel
as the pavement configuration, the exact EALF can be
worked out only by using distress models

• Instead of converting each axle pass into
equivalent standard axle passes, It will be
convenient to convert one truck pass into
equivalent standard axle passes.
• The factor that converts the number of trucks
into equivalent standard axle repetitions is
termed as vehicle damage factor or truck factor
• Therefore, Vehicle damage factor is the number
of standard axles per truck

• It is worked out by finding the directional
distribution and lane distribution factors
• Directional Distribution Factor (D)
– The ADT of trucks is the sum of daily truck
traffic volume in both directions
• – D factor is the proportion of ADT of trucks
occurring in the maximum direction
• – The D factor normally varies between 0.5 to
0.6

• Lane Distribution Factor (L)
– Is the proportion of truck traffic occurring on
the design lane
– Lane Distribution Factor depends on
- Number of lanes
- Traffic volume
• Daily Truck Traffic on Design Lane
= (ADT of Trucks) × (D) × (L)

Undivided Roads (Single Carriageway)
No. of Traffic Lanes in Two
Directions
Percentage of Trucks in
Design Lane (D×L)
1 100
2 75
3 40
Divided Roads (Dual Carriageway)
No. of Traffic Lanes in each
Direction
Percentage of Trucks in
Design Lane (L)
1 100
2 75
3 60
4 40

• ESAL = (ADT of Trucks) × (365) × (D) × (L) ×
(VDF) × GF
• GF =𝐺𝐹 =
1+𝑟 𝑛−1
𝑟
r = Growth rate in decimal
n = Design life in years

• Distress models relate the structural
responses to various types of distresses
• These are equations relating the allowable
number of repetitions of standard axle to the
appropriate pavement response as per the failure
criteria adopted

• N
• 𝑁𝑓 = 𝑘3*
1
∈ 𝑡
𝑘1
*
1
𝐸 𝑏𝑡
𝑘2
• =
Nf = No. of cumulative standard axles t produce 20%
cracked surface area
∈t = Tensile strain at the bottom of Bituminous Concrete
layer
E = Elastic Modulus of Bituminous Surface (MPa)
k1, k2 = Laboratory calibrated parameters
k3 = Transfer parameter

• 𝑁 𝑅 = 𝑘5*
1
∈ 𝑐
𝑘4
NR = No. of Repetitions to Rutting failure
∈c = Vertical subgrade strain
k4, k5 = Calibrated parameters

• Allowable number of repetitions (Ni) are
computed separately for each axle type I applying
the distress model
• Expected number of repetitions (ni) of each axle
type i are obtained from traffic cum axle
load survey
• Damage Ratio (DR), which is the ratio between
the expected repetitions and allowable
repetitions, is worked out for each axle type
• The cumulative DR of all axles should be less
than 1

California bearing ratio is defined as the ratio
(expressed as percentage) between the load
sustained by the soil sample at a specified
penetration of a standard plunger (50 mm
diameter) and the load sustained by the standard
crushed stones at the same penetration.

• This consists of causing a plunger of 50 mm
diameter to penetrate a soil sample at the rate of
1.25 mm/min.
• The force (load) required to cause the penetration is
plotted against measured penetration.
• The loads at 2.5 mm and 5 mm penetration are
recorded.
• This load corresponding to 2.5 mm or 5 mm
penetration is expressed as a percentage of
standard load sustained by the crushed aggregates
at the same penetration to obtain CBR value.

• The load – penetration curve may show
initial concavity due to the following
reasons:
– The top layer of the sample might have
become too soft due to soaking in water
– The surface of the plunger or the surface of
the sample might not be horizontal

• Draw a tangent to the load-penetration
curve where it changes concavity to
convexity
• The point of intersection of this tangent
line with the x-axis is taken as the new
origin
• Shift the origin to this point (new origin)
and correct all the penetration values

CBR
(per cent)
Maximum variation
in CBR value
5 ±1
5-10 ±2
11-31 ±3
31 and above ±5

• The average CBR values corresponding to 2.5 mm and
5 mm penetration values should be worked out
• If the average CBR at 2.5 mm penetration is more than
that at 5 mm penetration, then the design CBR is the
average CBR at 2.5 mm penetration
• If the CBR at 5mm penetration is more than that at 2.5
mm penetration, then the test should be repeated. Even
after the repetition, if CBR at 5mm is more than CBR at
2.5 mm, CBR at 5 mm could be adopted as the design
CBR.

The resilient modulus MR is the elastic modulus
based on the recoverable strain under repeated
loads, and is defined as
𝑀𝑟 =
𝜎 𝑑
𝜀 𝑟
𝜎 𝑑= deviator stress
𝜀 𝑟= recoverable elastic strain

Subgrade
E (MPa) = 10 × CBR if CBR<5% and
= 17.6 × (𝐶𝐵𝑅)0.64 for CBR > 5%
Granular subbase and base
𝑬 𝟐 = 𝑬 𝟑 × 𝟎. 𝟐 × 𝒉 𝟎.𝟒𝟓
𝑬 𝟐= Composite modulus of sub-base and base
(MPa)
𝑬 𝟑= Modulus of subgrade (MPa)
𝒉 = Thickness of granular layers (mm)

• Compaction is the process of increasing the bulk density of
a soil or aggregate by driving out air.
• For any soil, at a given compactive effort, the density
obtained depends on the moisture content.
• For any soil, an “optimum water content” exists at which it
will achieve it’s maximum density.

1. To increase strength and stability
2. To decrease permeability
3. To enhance resistance to erosion
4. Decrease compressibility under load and
minimize settlement

• Sheepsfoot
• Padfoot
• Vibratory Roller
• Grid Roller

• The peak dry unit weight is called the "maximum
dry density”.
• The Optimum Water Content, wopt, is the water
content at the soil’s maximum dry density.

• Proctor Compaction Test determines the optimum water
content and maximum dry density of for a soil.
• A required range for moisture is often specified by the
engineer:
• Ie, 3% below and 2% above optimum.
• For example, if optimum water content is 16%, the acceptable
range would be from 13% to 18%.
• Percent compaction is also specified:
• Meaning “required percentage of max dry density”
% Compaction = ρdry field /ρdry max

• Sand Replacement
• Core Cutter test.
• Nuclear Densometer

Particular Modified
Proctor
Standard
Proctor
IS 2720(VIII) 2720(VII)
Hammer Mass 4.8 Kg 2.6 Kg
Free Fall 45 cm 31 cm
Number Of
Layers
5 no. 3 no.
Number Of
Blows
25 25
Work Done In
Joules
270 joules 60.45 joules
Compaction
Efforts
4.46 times
than
Standard
Proctor
22% of
Modified
Proctor

Bituminous construction are classified into four
categories
• Interface Treatments
• Thin Bituminous surface Courses
• Bituminous Surface Courses
• Bituminous Binder Courses

• Prime Coat
• Tack Coat
• Crack Prevention Courses
SAM and SAMI

 Purpose Of Priming:
• To plug the capillary voids
• To coat and bond loose materials on the surface
• To harden or toughen the surface
• To promote adhesion between granular and the
bituminous layer
 Choice of Primer
• The primer shall be bitumen emulsion, complying
with IS 8887 of a type and grade as specified (SS-1)
• The use of medium curing cutback as per IS 217
shall be restricted only for sites at sub-zero
temperatures or for emergency applications

Purpose of Tack Coat:
• To ensure a bond between the new construction
and the old surface
Material for Tack Coat:
• The primer shall be bitumen emulsion, complying
with IS 8887 of a type and grade as specified
(RS-1)
Use of Cutback:
• It should be restricted for sites at subzero
temperatures or for emergency applications

20-30% more quantity of tack coat for milled
surface

Quantities of materials required for 10 m2 (20
mm)

A. Liquid Seal Coat:
comprising of a layer of binder followed by a cover
of stone chipping
Stone chips shall be of 6.7mm size defined as 100
per cent passing through 11.2 mm sieve and retained
on 2.36 mm sieve. The quantity used for spreading
shall be 0.09 cubic meter per 10 square meter area.
B. Premixed Seal Coat:
a thin application of fine aggregates premixed with
bituminous binder
The quantity of bitumen shall be 9.8 kg and 6.8 kg
per 10 m2 area for type A and type B seal coat
respectively

• Close-graded premix carpet is a fairly open
graded mix
• It is an alternative to the open graded premix
carpet and a seal coat
• It may be constructed in one operation

• The total quantity of aggregates used shall be
0.27 cum per 10 m2 area
• The quantity of binder shall be 22.0 kg and
19.0 kg for 10m2 area for Type A and Type B
surfacing respectively

• Preparation of Base to the Required Camber and
Shape
• Application of Primer
• Application of Tack Coat
• Spreading and Rolling First Layer of Coarse
Aggregates (0.5 cu.m/10 sq.m)
• Application of Binder - First Spray (15 kg/10
sq.m)

• Spreading and Rolling of Coarse Aggregates
for the Second Layer.
• Application of Binder - Second Spray (15 kg/10
sq.m).
• Application of Key Aggregates (0.13 cu.m/10
sq.m).
• Roll and Apply Additional key aggregates, if
required.
• Cover with a Seal Coat before opening to
Traffic.

• Lack of adequate compaction in field leads to
reduced pavement life
• Inadequate compaction of hot mix leads to early
oxidation, raveling, cracking and disintegration
before its life expectancy is achieved
• 1% excess voids results in approximately about
10% reduction in life

• Lack of attention to the air voids requirement of
compacted dense graded bituminous mixes is the
most common cause of poor pavement
performance
• Laboratory compaction produces more density,
hence 95-98% of laboratory density or 92% of
theoretical density is preferred in the field

• SCREED
The screed is the first device used to compact the
mat and may be operated in the vibratory mode.
Approximately 75 to 85 percent of Theoretical
Maximum Density (TMD) will be obtained when the
mix passes out from under the screed.

• ROLLERS
• Generally a series of two or three rollers is used.
Contractors can control roller compaction by
varying things such as the types of rollers used,
the number of roller used, roller speed, the number
of roller passes over a given area of the mat, the
location at which each roller works, and the pattern
that each roller uses to compact the mat.
• Approximately 92 to 95 percent TMD will be obtained
when all rollers are finished compacting the mat.

Typical roller position used in compaction are:
– Breakdown Roller The first roller behind the screed. It
generally effects the most density gain of any roller in
the sequence. Breakdown rollers can be of any type but
are most often vibratory steel wheel.
– Intermediate Roller Used behind the breakdown roller if
additional compaction is needed. Pneumatic tire rollers
are sometimes used as intermediate rollers because they
provide a different type of compaction (kneading action)
than a breakdown steel wheel vibratory roller, which can
help further compact the mat or at the very least,
rearrange the aggregate within the mat to make it
receptive to further compaction.

– Finish Roller The last roller in the sequence. It
is used to provide a smooth mat surface. Although
the finish roller does apply compactive effort, by
the time it comes in contact with the mat, the mat
may have cooled below cessation temperature.
Static steel wheel rollers are almost always
used as finishing rollers because they can
produce the smoothest surface of any roller type

• Maintenance: Is the routine work performed to
keep a pavement, under normal conditions of
traffic and normal forces of nature, as nearly
as possible in its as constructed condition.
• Maintenance: The function of preserving,
repairing, and restoring a highway and keeping it
in condition for safe, convenient, and economical
use

• It includes both physical maintenance activities
such as sealing, patching, and so forth and
traffic service activities including painting
pavement markings.
• Rehabilitation: restoring or betterment of
roadway such as resurfacing.

• All Pavements require maintenance.
• Stresses producing minor effects are
constantly working in all pavements.
• Stresses are:
• Change in temperature and moisture;
• Traffic;
• Small movements in underlying or adjacent earth.
• Distresses are visible evidence of pavement wear (i.e.
they are the end result of the wear process which
begins when construction ends).
• Water lines and other utilities are major area of
pavement maintenance.

Functional Overlay
Reconstruction

Importance:
• Protect investments made in highways.
• Economic & safety of public road system.
Challenges:
• increased roads (additional mileage of travel),
• vehicle sizes, and traffic.
• Traveling public expect higher level of maintenance.
• Size of maintenance budget.

• Purpose: to capture information about
maintenance activities performed & resources
expanded.
• Maintenance management systems do not
manage programs, reduce cost or improve
performance, rather they provide maintenance
engineers with the information and analytical
tools needed to allow them to do so.

• Elements of maintenance management programs:
• Development of an annual work program (defining
activities, quantities, establish performance
standards, road inventory & inspection, estimate size
of the work program).
• Budgeting & allocating resources (labor, equipment,
Materials).
• Work authorization & control (various
administration levels).
• Scheduling (balance of workload throughout the
year).
• Performance evaluation (work progress &
productivity).
• Fiscal control (monitor status of expenditures
yearly).

• Road surfaces
• Shoulders & approaches.
• Roadsides
• Bridges, & drainage structures.
• Traffic controls & safety devices.

• Bituminous surfaces
• Failures due to: weathering, failure of base or
subgrade due to material quality or compaction or
improper drainage.
• Repairs:
• Patching
• Paint patching
• Scarifying
• Resealing.
• Non skid surface treatment

• Well graded gravel shoulder : blading to proper
slope and filling ruts or worn out materials.
• Turf shoulders: filling holes & ruts, blading,
seeding, mow & clean shoulders (weed control).
• Approaches: include public side roads, private
driveways, ramps, & turnouts.
• Approach maintenance is similar to shoulder
maintenance + extra efforts to maintain
potholes, ruts, and other types of deterioration

• Roadside: include area between traveled surface &
the limit of the right-of-way (medians, roadside
parks, right-of-way fences, picnic tables, ..etc.
• Vegetation management & control (include mowing,
weed eradication & control, seeding, planting
vegetation, & care of trees & shrubs).
• Mowing is done to provide sight distance, improve
drainage, reduce fire hazards, & improve
appearance of the roadway.
• Seeding & planting vegetation are important for
prevention of erosion.
• Maintenance of rest areas.
• Litter control.

• Bridges: Maintenance is needed to minimize
deterioration or repair damage caused by accidents,
floods, or other unforeseen events.
• Steel bridges: cleaned & painted to prevent erosion.
• Concrete bridge decks deterioration: Corrosion of
reinforcement bars due to penetration of water &
deicing salts or chemicals.
• Bridge decks with minor deterioration: patch with
special concrete.
• Bridge decks with major deterioration: Overlay or
remove & construct

• Drainage structures
• Should be kept in good working conditions.
• Surface drainage, ditches, & culverts
• Safety devices:
Guardrails, barriers, impact attenuators, pedestrian
overpasses & underpasses, fence to restrict access of
pedestrians & animals.
• Safety devices should be frequently &
systematically inspected & repaired

• Proper maintenance extend pavement life.
• However, best-maintained pavements will
deteriorate with time and will need
rehabilitation.
• Conventional rehabilitation:
• Reconstruct with all new material
• Patch & overlay with new wearing surface.

Types of Overlays
• Asphalt overlay over asphalt pavements
• Asphalt overlays on CC pavements
• CC overlays on asphalt pavements
• CC overlays on CC pavements

Measurement and estimation of the strength of
the existing pavement
Design life of overlaid pavement
Estimation of the traffic to be carried by the
overlaid pavement
Determination of the thickness and the type of
overlay

Basic concept
• Thickness of overlay is the difference between
the thickness required for a new pavement and
the effective thickness of the existing pavement
• ℎ 𝑜𝑙=ℎ 𝑛 − ℎ 𝑒
Where,
ℎ 𝑜𝑙=thickness of overlay
ℎ 𝑛 = thickness of new pavement
ℎ 𝑒 = effective thickness of existing pavement

All thicknesses of new and existing materials
must be converted into an equivalent thickness
of AC
ℎ 𝑒 =
𝑖=1
𝑛
ℎ𝑖 × 𝐶𝑖
ℎ𝑖 = thickness of layer i
𝐶𝑖 = conversion factor for layer i

• The structural strength of pavement is assessed
by measuring surface deflections under a
standard axle load
• Larger pavement deflections imply weaker
pavement and subgrade
• The overlay must be thick enough to reduce the
deflection to a tolerable amount
• Rebound deflections are measured with the help
of a Benkelman Beam

• Condition survey and deflection data are used to
establish sections of uniform performance
• At least 10 deflection measurements should be
made for each section per lane subject to a
minimum of 20 measurements per km.
• If the highest or the lowest deflection values
for the section differ from the mean by more
than one-third of the mean, then extra
deflection measurement should be made at 25 m
on either side of point where high or low values
are observed.

• Visual inspection of the road stretch and
grouping into sub-stretches
• Assessment of pavement cracking – type &
percentage cracked area
• Rut depth measurements
• Observations on other types of pavement
deterioration

• axle load of 8170 kg / load of 4085 kg on dual
wheels
• tyre pressure, p = 5.6 kg / cm2
• standard pavement temperature = 35o C
• highest subgrade moisture content soon after
monsoon
-Some precautions during rebound deflection
Observations
• very low or zero values
• variation of individual values, not more than one
third of mean value

• Measurement of pavement temperature (at one
hour intervals)
• Measurement of field moisture content of
subgrade soil
• Typical subgrade soil samples for lab. Tests
(soil classification)
• Other data to be collected
- annual rain fall
- traffic data : classified volume of vehicles of
gross load over 3 t, growth rate, axle load data /
VDF values

• Leg correction, if any, at each point of deflection
observation:
• - If (𝐷i ~ 𝐷f) is less than 0.025 mm (2.5 div.), 𝐷 = 0.02 (D0
~ 𝐷f)
• - If (𝐷i ~ 𝐷f) is more than 0.025 mm (2.5 div.), 𝐷 = [ 0.02
(𝐷0 ~ 𝐷f) + 0.0582(Di – Df) ]
• Mean deflection, 𝑫
• Characteristic Deflection, 𝑫𝒄 = ( 𝑫 + 2𝝈 ) for important
roads to cover
• - 97.7 % deflection values, or 𝐷c = ( 𝐷 +𝜎 )
for low traffic roads, to cover 84.1 % deflection values
Application of temperature correction factor @ 0.01 mm
per 𝒐𝑪 variation from the standard temperature of 35 𝒐𝑪
or 0.01 (𝒕~35)

Temperature Correction
• Stiffness of the Bituminous layers get affected
due to which deflections vary
• Standard temperature is 35 𝑜𝐶
• Correction for temperature variation on
deflection values measured at pavement
temperature other than 35 𝑜𝐶 should be 0.01mm
for each degree change from the standard
temperature.

Correction for Seasonal Variation
• Deflection depends upon the change in the climate
• Worst climate (after monsoon)-considered for design
• Depends on subgrade soil and moisture content
• Correction for seasonal variation depends on type
of soil subgrade (sandy/gravelly or Clayey with
PI<15 or Clayey with PI>15), field moisture content,
average annual rain fall (<1300 mm or >1300 mm)

• The design traffic is considered in terms of the
• cumulative number of standard axles ,
𝑁𝑠 =
365 × 𝐴[(1 + 𝑟) 𝑥 − 1]
𝑟
× 𝑓
• 𝑁𝑠 = The cumulative number of Standard Axles to
be catered for in the design
• 𝐴 = Initial Traffic in the year of completion of
construction on design lane
• 𝑟 = Annual growth rate of commercial vehicles
• 𝑥 = Design life in years
• 𝑓 = Vehicle Damage Factor

• Design curves relating characteristic pavement
deflection to the cumulative number of standard
axles are to be used.
• The Deflection of the pavement after the
corrections i.e., Characteristic Deflection is to
be used for the design purposes.
• The design traffic in terms of cumulative
standard number of axles is to be used

• The thickness obtained from the curves is in
terms of Bituminous Macadam construction.
• If other compositions are to be laid then
-1 cm of Bituminous Macadam = 1.5 cm of
WBM/Wet Mix Macadam/BUSG
-1 cm of Bituminous Macadam = 0.7 cm of
DBM/AC/SDBC

Highway Design - Techniques for proper Planning and Execution .

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