INDUCTION TRAINING REPORT

SURVEY AND DESIGN DIVISION

WENDY OFORI
TECHNICIAN ENGINEER
DECEMBER, 2022
 INDUCTION TRAINING REPORT – SURVEY AND DESIGN DIVISION

TABLE OF CONTENTS
1.0 Introduction ............................................................................................................................................. 1
1.1 Organizational Structure ..................................................................................................................... 2
2.0 Survey Section ........................................................................................................................................ 3
2.1 Map Study and Rout Planning ............................................................................................................ 3
2.2 Survey Equipment and Their Uses.................................................................................................. 3
2.2.1 Level Instrument .......................................................................................................................... 3
2.2.2 Total Station ................................................................................................................................. 3
2.2.3 Global Positioning System ........................................................................................................... 3
2.3 Pillar Building and Inspections ........................................................................................................... 4
2.4 Route Location .................................................................................................................................... 4
2.4.1 Factors That Affect Route Location............................................................................................. 4
2.4.2 Route Survey Stages .................................................................................................................... 4
3.0 Design Section ........................................................................................................................................ 6
3.1 Introduction to the Road Design Guide .............................................................................................. 6
3.2 Geometric Design of Roads ................................................................................................................ 6
3.3 Road Classifications for Planning & Design ...................................................................................... 6
3.4 Elements of Road Geometry ............................................................................................................... 7
3.4.1 Horizontal Alignment .................................................................................................................. 8
3.4.1.1 Horizontal Curves ..................................................................................................................... 8
3.4.1.2 Basic Steps in Geometric Design Using GHA RDG ................................................................ 9
3.4.1.3 Superelevation......................................................................................................................... 10
3.4.1.3.1 Superelevation Transition Section ....................................................................................... 12
3.4.1.3.2 Superelevation Design Using GHA RDG ............................................................................ 12
3.4.1.4 Practical Experience ................................................................................................................ 13
3.4.2 Vertical Alignment..................................................................................................................... 13
3.4.2.1 Vertical Curves ....................................................................................................................... 13
3.4.2.2Types of Parabolic Curves ....................................................................................................... 13
3.4.2.3 Basic Steps in Geometric Design (Using the GHA RDG) ...................................................... 14
3.4.2.4 Practical Experience ................................................................................................................ 15
3.4.3 Cross-Section ............................................................................................................................. 15
3.4.3.1 Element of a Road Cross Section ............................................................................................ 15
6.0 Introduction to Design Software ........................................................................................................... 21

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7.0 Appendices............................................................................................................................................ 22
List of Tabbles
Table 3.1: Road classification by terrain type
…………..………………………………………………… 7
Table 3.2: Carriageway width of the various class of road
……………………..………………………. 15
Table 3.3: Shoulder width of the various class of road
…………………………………………………. 15

List of Figures
Figure 2.1: How pillars are identified
…………..………………………………………………………… 4
Figure 3.1 Types of horizontal curves
……………………………………………………………………. 9
Figure 3.2: Superelevation attainment diagrams
……………………………..………………………….. 11
Figure 3.3: Crest Vertical Curve
…………………………………...……………………………………. 13
Figure 3.4: Sag Vertical Curve
………………………………………………………………………….. 14
Figure 3.5: Typical elements of a highway cross section
……………………………………………….. 16

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 INDUCTION TRAINING REPORT – SURVEY AND DESIGN DIVISION

1.0 Introduction
The survey and design division, under the development department provides services in the
following areas:
1. Engineering survey for the design of roads and drainage structures as well as survey for
landed properties of the Authority.
2. Design of roads and drainage structures.
3. Vetting of designs by private consultants both in the office and on the field.
4. Provision of right of way clarification and design of accesses for developers whose
properties adjoin our roads.
5. Provision of Geographical Information System services to assist in the provision of digital
maps of trunk roads and update of road conditions.
6. Training of Newly Recruited Engineers and other professionals as we as National Service
Personnel and students from our tertiary institutions.

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1.1 Organizational Structure

Director of Survey and

Design

Location Manager
Design Manager

Design Design
Location Engineer Location Engineer Drawing
Engineer Engineer
(Examination) (Operation) Supervisor
(Highway) (Drainage)

Surveyors Surveyors
Surveyors Draftsman
(Team A) (Team B)

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2.0 Survey Section

2.1 Map Study and Rout Planning
Map study is used as a tool to plan a route from one point (say, point A) to another (say, point B).
This involves the use of a topographical map (either digital or on paper) as guidance making
alternative route choices for traversing from point A to point B. This map gives an indication of
the nature of relief features between point A and point B. The probable alignment can be
established by:
• Avoiding valleys, ponds or lakes,
• Avoiding bends of rivers,
• Exploring the possibility of crossing through a mountain pass, if the proposed route has to
cross a row of hills.
2.2 Survey Equipment and Their Uses
2.2.1 Level Instrument
The level instrument is made of:
• Levelling head with three-foot screws.
• A telescope that provides a line of sight to bisect the distant object.
• To make the line of sight horizontal, Bubble tubes are used.
• Tripod for supporting the instrument.
It is use for:
• Height measurement
• Setting out
2.2.2 Total Station
Total station is a surveying equipment combination of Electromagnetic Distance Measuring
Instrument and electronic theodolite. It is also integrated with microprocessor, electronic data
collector and storage system. The instrument can be used for
• Horizontal and vertical angle measurement
• Distance measurement
• Height measurement
2.2.3 Global Positioning System
It is one of the Global Navigation Satellite Systems (GNSS) that provides geolocation and time
information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line
of sight to four or more GPS satellites. The GPS is use for

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• Locating: determining a position

• Navigating:
• Tracking: monitoring objects
• Mapping: creates maps of the world
• Height measurement
2.3 Pillar Building and Inspections
Control points are built in pairs for intervisibility purposes.
They are built in road reservations (right of way). The road reservation for National, Inter Regional
and Regional roads are 90m (45m on each side) and 60m (30m on each side) respectively.
Pillars must not be built under trees, close to high buildings and high-tension cables, etc.
Pillars are placed at 1km interval.
Inscriptions are written on pillars for identification.

GHA

MP .2021 Year of Construction

Mankesim
to 1
Praso Pillar Number

Figure 2.1: How pillars are identified

2.4 Route Location
The major aim of a route location exercise is to select a roadway alignment that best satisfies traffic
desires and transportation needs within a region, district, locality or travel corridor at a minimum
overall cost to the economy and least destruction to the environment.
2.4.1 Factors That Affect Route Location
To achieve this, many factors must be taken into consideration during the survey; these in the main
relate to
• Topography or nature of the terrain
• Drainage consideration
• Suitable bridge sites
• Earthworks:

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• Construction materials
• Land use patterns
• Economic considerations
• Field reconnaissance
• Sites of historic, social and cultural value:
2.4.2 Route Survey Stages
In principle, there are four stages to the selection of the final and best routes. These are:
1. Map study
2. Reconnaissance survey
3. Preliminary survey
4. Final location and detailed survey
The first three stages of the survey consider all the possible alignments in relation to the factors
that affect route location given above and any other requirement. The fourth stage is meant to
provide a detailed survey of the selected or final alignment.

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3.0 Design Section

3.1 Introduction to the Road Design Guide
The road design guide is to be used primarily by road designers in Ghana Highway Authority and
by consultants working on behalf of the authority.
The use of design standards on any particular class of is to fulfill three objectives, namely
• To ensure minimum levels of safety and comfort of road users.
• To arrive at an economic design.
• To maintain uniformity in alignment, drainage and other road facilities.
• To assist engineers in designing the engineering details of the road sections
3.2 Geometric Design of Roads
It is a branch of highway engineering concerned with the positioning of the physical elements of
the roadway according to standards and constraints.
The basic objectives are
• To optimize efficiency
• To optimize safety
• Minimize cost
• Minimize environmental damage
3.3 Road Classifications for Planning & Design
Roads are classified according to the type of terrain for uniform design standards. Such
classification is shown in Table 1.0

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National

National

Regional

Inter-Regional

Table 3.1: Road classification by terrain type

3.4 Elements of Road Geometry
The elements, combined provide a three-dimensional layout for a roadway. Each of these elements
are designed in accordance with various standard of practices such as GHA Road Design Guide,
AASHTO, etc. to meet traffic flow characteristics.
Geometric roadway design can be broken into three main parts:
• Horizontal alignment
• Vertical alignment
• Cross-section

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3.4.1 Horizontal Alignment

Horizontal alignment is the plan (top) view of a road which consists of a series of circular curves,
tangents(straights) and transition curves. It also includes the design of superelevation and transition
curve. The design of horizontal alignments requires the understanding of design speed and
horizontal curves.
The design speed depends on the classification of road and the type of terrain. For example, the
design speed expected for a National Road will be much higher than a regional road, hence the
curve geometry will vary significantly.
3.4.1.1 Horizontal Curves
A horizontal curve provides a transition between two tangent strips of roadway, allowing a vehicle
to negotiate a turn at a gradual rate rather than a sharp cut. The types of horizontal curves include:
1. Simple curve: A simple curve has a constant circular radius which achieves the
desired deflection without using an entering or exiting transition.
2. Compound curve: This is a circular curve which is comprised of a series of two or more
simple curves of different radii which turn in the same direction.
3. Reverse curve: A reverse curve consists of two simple curves joined together, but curving
in opposite directions.
4. Broken-Back Curve: Two curves in the same direction separated by a short straight.
5. Switchback Curves: Switchback or hairpin curves are used where necessary in traversing
mountainous and escarpment terrain.

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Reverse Curves
Figure 3.1 Types of horizontal curves

3.4.1.2 Basic Steps in Geometric Design Using GHA RDG

Horizontal Alignment
a) Determine your design speed based on the functional classification and the topography of
the corridor (GHA RDG Table 2.2.1).
b) Extract all the minimum curve parameters that goes with the specified design speed from
the GHA RDG.
Minimum redius (Table 4.2.1)
Minimum curve length (Table 4.2.2)
Maximum superelevation (Table 4.2.3)
Curve radii where superelevation is unnecessary (Tables 4.2.4)
Minimum transition length (Table 4.2.5)
Radii where there are no need of transition (Tables 4.2.6)
Ratio of superelevation runoff (Table 4.2.8)
c) Put in your straights making sure they are as much possible parrallel to existing road (if
possible).
d) Where the straights (tangent) meet is called the point of intersection (IP or PI) and the
intersecting angle called the deflection angle (∆).

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e) For an existing road, you can extract the existing curve radius using the relation between
the external distance (E) and the deflection angle in the formulae
1
f) E = R [ ∆ − 1]
Cos( )
2

g) Tangent length and length of curve can be determined from the following formulae
∆
h) T = Rtan 2
π
i) L = 180 R∆

j) Put in your curve where ever you have an IP. For curves that require transitions, curve
parameters can be obtained from the speed table at the back of the GHA RDG (pg. 113-
121)
3.4.1.3 Superelevation
The inward transverse inclination which is provided to the cross-section of the pavement of road
at the horizontally curved portion of the roads is known as superelevation.
Superelevation on a road is provided to counteract the effect of centrifugal forces and to minimize
the tendency of the vehicle to overturn or skidding off the road.
Superelevation can be attained by
a) rotating the pavement with respect to the inner edge,
b) rotating the pavement with respect to the centre of the pavement or
c) by rotating the pavement with respect to the outer edge of the pavement.

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Figure 3.2: Superelevation attainment diagrams

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3.4.1.3.1 Superelevation Transition Section

Superelevation is provided at a gradual rate along the length of the transition curve. It is done by
changing crowned camber a single cross slope before the start of the circular curve. Full
superelevation is attained at the end of the transition curve or at the start of the circular curve.
However, the transition sections of superelevation are;
• Tangent runout -Length of roadway needed to accomplish a change in outside-lane cross
slope from normal cross slope rate to zero.
• Superelevation runoff - Length of roadway needed to accomplish a change in outside-lane
cross slope from 0 to full superelevation or vice versa.
3.4.1.3.2 Superelevation Design Using GHA RDG
a) With our design speed and curve radius already determined, we can go ahead and determine
all the design parameters for our superelevation design.
Normal cross slope rate, eNC (%)
Maximum superelevation, emax (%) (pg 118)
Deflection angle, ∆
Ratio of superelevation runoff, q (Table 4.2.6)
b) Determine your transition length if spirals are required using the formulae
0.06V 3
LS =
R
c) Compute for your superelevation runoff length LR. For curves that require transition,
superelevation runoff length equals spiral length (LR = LS). However, there is no need to
calculate for LR.
B. emax
LR =
q
Where, B = Half width of the carriageway
Note that in simple curves, the superelevation runoff is provided 2/3 in the straight
portions and 1/3 in the circular curves.
d) Determine your tangent runout length and the formulae is given by
eNC
LT = xL
emax R
e) Determine your curve length using the formulae
∆−2∅S
LC = , for curves with transition
D

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∆
LC = D 100, for curves without transition

f) Draw the superelevation diagram based on your point of pavement rotation.

g) Determine the cross section of the superelevated section of the road.
3.4.1.4 Practical Experience
An example of a horizontal alignment design can be found in Appendix 1 and that of
superelevation design can be found in Appendix 2.
3.4.2 Vertical Alignment
Vertical alignment is the elevation (profile) view of a road. It comprises of road slopes called
gradients connected by parabolic vertical curves.
3.4.2.1 Vertical Curves
Vertical curves are used to provide smooth transition between consecutive gradients. It also
increases sight distance across two grades. The types of vertical curves in use are;
• Circular curves
• Parabolic curves.
3.4.2.2Types of Parabolic Curves
1. Crest curves
• The gradient at the beginning of a curve is higher than that at the end of the curve.
• The algebraic difference between the gradient at the beginning of a curve and the
gradient at the end of the curve is negative.

G1 G2
G = G2 – G1
= Negative
Figure 3.3: Crest Vertical Curve

2. Sag curves
• The gradient at the beginning of a curve is lower than that at the end of the curve.
• The algebraic difference between the gradient at the beginning of a curve and the
gradient at the end of the curve is positive.

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G1 G2
G = G2 – G 1
Figure 3.4: Sag Vertical Curve = Positive

3.4.2.3 Basic Steps in Geometric Design (Using the GHA RDG)

Vertical Alignment
a) With our design speed already determined, we can go ahead and determine all the minimum
vertical curve parameters for our vertical alignment design.
Maximum gradient (Table 4.3.1)
Minimum gradient (0.4%, irrespective of the speed, this is a function of drainage)
K values for crest (Table 4.3.4)
K value for sag (Table 4.3.5)
Minimum vertical curve length (Table 4.3.6)
b) Length of vertical curve is given by L = KG, where G is the algebraic difference between
the two grades G1 and G2.

Where,
VIP = Vertical intersection point of tangent lines
PVC = Point of vertical curvature
PVT = Point of vertical tangency
L = Length of curve
G1 = Initial roadway grade (%)
G2 = Final roadway grade (%)
c) Determine level on grade and deduct vertical offsets to get level on curve.

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3.4.2.4 Practical Experience

An example of a vertical alignment design can be found in Appendix 3.
3.4.3 Cross-Section
3.4.3.1 Element of a Road Cross Section
1. Travel Lanes / Carriageway
• Width of pavement on which vehicles travel.
• The cross slope of carriageways ranges from 1 – 2%.
Function of Road Width per Lane(m)
National Roads 3.65
Inter – Regional Roads 3.65
Regional Roads 3.65
Table 3.2: Carriageway width of the various class of road
2. Road Shoulders
• Shoulders are provided along the road edge to serve as emergency lanes for
vehicles.
• The cross slope of shoulders ranges from 2 – 4%.
Function of Road Width per Lane(m)
National Roads 2.5
Inter – Regional Roads 2.0
Regional Roads 1.5
Table 3.3: Shoulder width of the various class of road
3. Median
• The median strip is normally introduced on roads with high traffic volume, high design
speed and four or more lanes.
• It prevents traffic accidents by separating opposing traffic streams.
• Pedestrians can make use of it as a refuge area to cross the road safely and easily.
• It provides space for the installation of street lights and other traffic control devices.
4. Right-Of-Way
• Total land required for the construction of the highway

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• Needs to be wide enough to accommodate all the elements of highway cross section
and planned widening of the highway, and all public utility facilities to be installed
along the highway
• Examples:
National Road – 90m
Regional/Inter-regional Road – 60m

5. Side slope
• The slope of earth in filling or in cutting is called Side slope.
• It imparts stability to the earthwork.

Figure 3.5:

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4.0 Drainage Design

4.1 Why Drainage Design
The main purpose of drainage design is to ensure safe discharge of rainwater captured within the
development to public drains outside site boundary. It is also to prevent any flooding and unwanted
flow of water out of the site.
4.2 Key Terms
The following are key terms and definitions you should know while designing drainage:
Drains – Channel or pipe carrying off surplus liquid, especially rainwater.
Invert level – Base, lowest interior level of the drain.
Width – Horizontal dimension of the drain.
Depth – Vertical dimension of the drain
Discharge –
Culvert – Structure that allows water to flow under a road.
Gradient – Measure of how steep a slop is, typically measured as a ratio of vertical to horizontal
distance.
Peak runoff – Highest possible rate of flow of water at a specified point along the drain channel.
Catchment Area – An area that contributes to the discharge in a drain.
4.3 Drainage Design of Roadside Drains Using GHA RDG
4.3.1 Hydrology
a) Determine catchment area (A), km2
b) Determine the design rainfall intensity (I), mm /hr
c) The design parameters needed to obtain the rainfall intensity are;
• Time of concentration which is given by the formular
58.5L
Tc =
60A0.1 S 0.2
Where, L = Length of longest river with the catchment.
A = Catchment area (km2)
S = Catchment slope (m/km)
∆H
S=
L
Where, ∆H = Highest contour heigh(m) – Lowest contour height(m)
• Return period for drainage structures (Table 6.4.1)

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d) Calculate catchment area runoff coefficient (C)

CA1 + CA2 + CA3
C=
A1 + A2 + A3
e) Runoff coefficients of the various surface types (Table 6.4.3)
f) Calculate maximum run-off using the formulae
1
Q= C. I. A
3.6
4.3.2 Hydraulics
a) Assume the size of the drainage structure
b) Calculate the average velocity of flow for the structure using the formulae
1 2/3 1/2
V= R S
n
Where, V = Average velocity of flow (m/sec)
a. n = coefficient of roughness (sec/m1/3) Table 6.4.4
b. S = Slope of drain
A
c. R = Hydraulic mean depth, given by the formulae R = P

Where, A = Flowing water section area (m2)

d. P = Length of wetted perimeter (m)
c) Calculate design discharge capacity using the formulae
QC = A. V
d) Compare maximum run-off and design discharge capacity.
e) If Q ≤ QC, the design is acceptable
f) If Q > QC, the design is not acceptable
4.3.3 Hydraulic Design of Culverts
a) Assume the size of the drainage structure.
b) Indicate the maximum run-off, Q for design periods of 15years and 25years.
c) Inlet Control. The inlet control calculations determine the headwater elevation required to
pass the design flow through the selected culvert configuration in inlet control. The inlet
control nomographs of Appendix 5 are used in the design process.
d) Determine your head water depth ratio using the inlet control monographs Chart 8A for
box culverts and Chart 1A for pipe culverts.
e) Multiply HW/D by the culvert height, D, to obtain the required headwater (HW).

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f) If the approach velocity is neglected, HW equals the required headwater depth (HWi).
g) Outlet Control
The outlet control calculations result in the headwater elevation required to convey the
design discharge through the selected culvert in outlet control.
h) Determine the tailwater depth above the outlet invert (TW) at the design flow rate. This is
obtained from backwater or normal depth calculations. The inlet control nomographs of
Appendix 5 are used in the design process.
i) Enter the appropriate critical depth chart (Chart 14A for box culverts and Chart 4A for pipe
culverts) with the flow rate and read the critical depth (dc). dc cannot exceed D!
j) Calculate (dc + D)/2
k) Determine the depth from the culvert outlet invert to the hydraulic grade line (ho).
l) Determine the appropriate entrance loss coefficient, ke, for the culvert inlet configuration.
m) Determine the losses through the culvert barrel, H, using the outlet control nomograph
Chart 15A for box culverts and Chart 6A For pipe culverts.
n) Estimate the headwater depth at the outlet control using the formulae
HWO = H + ho − LSO
o) Compare the headwater elevations calculated for inlet (HWi) and outlet control (HWo). The
higher of the two is designated the controlling headwater elevation.
p) Calculate for your outlet velocity.
q) If the required headwater depth (HWi) is less than the allowable headwater depth, the
design is ok.
r) Repeat the design process until an acceptable culvert configuration is determined.
4.3.4 Practical Experience
An example of the design of a trapezoidal drain and a box culvert can be found in Appendix 4.

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5.0 Vetting of Drawings

One of the functions of the Survey and Design Division is to vet designs produced by consultants.
The Ghana Highway Authority Design Guide is used as a basis for this verification.
One important parameter used for the review is the design speed. With this speed the horizontal
alignment is reviewed using the;
• Radius above which transitions are not required
• Absolute minimum radius
• Minimum curve length
• Minimum spiral length
• Maximum superelevation
• Superelevation application and
The vertical alignment is reviewed using the;
• K factor for the sag curve
• K factor for the crest curve and
• Minimum curve length
• Minimum gradient of slopes
• Check if curve parameters are clearly shown
• Check if excessive cutting was avoided.

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6.0 Introduction to Design Software

A geometric and drainage design of Eshiem – Oda Road (R62) was undertaken using AutoCAD
Civil and ArcGIS. The output of the design is as follows:
• Typical cross sections (for rural and urban sections).
• Plan and profile (with Laybys in settlements) showing all cross-drainage structures.
• Drainage layout
The plan and profile, drainage layout and drawings can be found in Appendix 6 can be found in
Appendix 6.

The start station is 24+350 (south). The Pavement structure consist of a 200mm Subbase, 200mm
Base and Double Surface Treatment for carriageway and single surface treatment for shoulders. A
catchment extent of 75m was assumed on either side of the road for all longitudinal drains in
settlements.

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7.0 Appendices

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