Case Study on Geometry of Four Lane Highway

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 10 Issue: 09 | Sep 2023 www.irjet.net p-ISSN: 2395-0072
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Case Study on Geometry of Four Lane Highway
Vaibhav B. Chame 1, Prof. Ashwini R Patil2
1 Student, D.Y. Patil College pf Engineering, Pune, Maharashtra, India.
2 Prof., Dept. of civil Engineering, D.Y. Patil College pf Engineering, Pune, Maharashtra, India.
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Abstract - In India, vehicular traffic is growing rapidly.
Increased traffic volume leads to widening of existing roads &
construction of new roads. Efficient geometry of road helps to
reduce accidents, provide comfort to road users, reduce travel
time, avoid traffic congestions, etc.
Previous studies have concluded that improper design of
geometric elements of roads results in accidents, traffic
congestions, uncomfortable journey, etc. Proper design of
geometric elements of road shall be taken care at design &
development stage of road to avoid redevelopment/
reconstruction & to maintain cost efficiency.
Key Words: Horizontal Curve, Vertical Curve,SightDistance,
Camber, Cross Section, Carriageway, Shoulder.
1. INTRODUCTION
Geometric design of roads depends on traffic volume,
weather conditions, terrain, etc. The geometric design of a
highway deals with features of road which consists of cross
section of roads, median width, intersections, horizontal &
vertical curve, sight distance etc. General interpretations of
some important geometric elements of road are mentioned
below
Horizontal Curve: A horizontal highway curve is a plan to
provide a change in direction in the centre line along the
highway. Horizontal alignment includes the design of
horizontal curves, super elevation, transitionlengths,speed,
extra widening. Simple curve, compound curve, reverse
curve and spiral curve these are the types of horizontal
curve.
Vertical curve: Vertical curve are provided to change the
slope in the road. Sag/valley curve and summit curvearethe
types of vertical curve.
Sight Distance: Sight distancelengthofroadislengthvisible
ahead the driver at any instance.
Camber: Cross slope can be defined as the slope of a
roadway perpendicular to the centre line. If a road were
completely level, water would drain off it.
Shoulder: It is the part of formation width except carriage
ways. They are used by the vehicular traffic as the
emergency lanes or sometimes as service lanes.
Superelevation: The outer edge of the road with respect of
the inner edge of road is raised, this is called superelevation.
Median: Median separates the opposite traffic and provides
safety features as well as reduces headlight glare, improve
comfort for night driving. Two types of mediansprovided on
highways as per requirement i.e., raised and depressed
median.
Cross Section: The cross section of a roadway is the view
obtained in a section between the right-of-way lines cut
perpendicular to the direction of travel along the road. It
includes features on the travelledportionoftheroadusedby
vehicular traffic as well as on the roadside.
Vertical & horizontal clearance at underpass: Efficient
vertical and horizontal clearance shall be provided at
underpasses to allow safe passage to vehicle passing under
2. OBJECTIVE
 To examine the existing geometry of highway
 To identify the safety issues in highway design
 To providethe simple geometric design tomeet
all expectation of road at reasonable cost.
3. LITERATURE REVIEW
In past periods many studies have been done on geometric
design elements of roadtoimproveroadsafetyandoptimum
efficiency of use. The study will help to minimize the errors
occurring in roadway design which is helpful for the system
to avoid future cost and difficulties with improved traffic
operation.
Zhang Yingxue (2009), stated that it is important for traffic
accident to bring high accident rate if the sight distance is
not enough and this is visible on the places where have the
bad visual distance of small horizontal curve radius, small
crest vertical curve radius, intersection, and lack of
overtaking sight distance on some road section. In order to
ensure traffic safety, the traveling sight distance should be
design enough when design horizontal orvertical alignment.
Vikas Golakot (2018) his thesis included that the aim of his
study is to find the role of the geometric factors of road on
accident rate in the case of plain terrain and also find the
extent to which these factors affecttheaccidentrateforrural

areas. The study aims to find the impact of factors like extra
widening, horizontal radius, sight distance, K-value, super
elevation, horizontal arc length, vertical arc length, vertical
gradient on the accident rate and aims to study the
significant factors causing accidents and to find the values
for future design of roads.
Indian Road Congress SP 84: 2019. It gives the specification
and standards for four laning highways.
4. METHODOLGY
It is proposed to study for the national highway starting
from chainage Km. 270+000 near Shelad village and end at
Km. 315.000 near Nandura village in Maharashtra State.
Various factors are studied and verified with the relevant
specification and standards. Detailed primary data for the
selected road iscollectedfromcompanies/organizations and
verified the designed parameters with respect to IRC
provisions.
5. DATA ANALYSIS
Thorough study of plan and profile drawings & data
collected, site visit to selected stretch, analysis of features,
etc are done. Noted observations are listed below:
 Project stretch is located in Maharashtra state,
India.
 The terrain of road through which it passingisplain
terrain.
 The length of the project stretch is around 45 km.
 Justification with IRC provision - proposed key
elements are checked with the IRC provisions to
validate the design, the same are mentioned as
below
Table -1: IRC Validations
Items IRC Provision Remarks
Carriage -
way
Carriage way width 7 mtr on
each side [Fig 2.4 – IRC: SP: 84:
2019]
Followed
Camber
Crossfall on straight section,
2.5% for bituminous surface
[Clause No 2.8, IRC:SP:84:2019]
Followed
Design
speed
Minimum design speed for plain
and rolling terrain 80 Kmph
where ruling speed is 100 Kmph
[Clause No 2.2, IRC:SP:84:2019]
Followed
Horizontal Curve: The horizontal alignment data based on
the plan and profile is analysed step by step and the
observation related to each design element is recorded.
On horizontal curves with radius up to 300 m, width of
pavement and roadway in each carriageway shall be
increased which is also analysed.
Table -2: Horizontal Curve Radius with Speed
Sr
No
Chainage
Curve
Radius
Remarks
1 Km. 270+154 400 m
100 Kmph
(Maximum speed)
2 Km. 271+929 590 m
100 Kmph
(Maximum speed)
3 Km. 274+506 7000 m
100 Kmph
(Maximum speed)
4 Km. 274+938 400 m
100 Kmph
(Maximum speed)
Table-3: Extra Width of Pavement and Roadway in Each
Carriageway
Radius of curve (m) Extra width (m)
75-100 0.9
101-300 0.6
Vertical Curve: The vertical curve data based on the plan
and profile is analysed step by step and the observation
related to each design element is recorded.
Table -3: Vertical Curve Radius with Type and Length.
Junction geometry: Properly designed intersections shall
be provided at all road crossings/junctions, so as to ensure
that no intersection remains without safe and efficient
design. Following Observation are recorded at minor
junction at Ch. 275+238 and Ch. 282+740 & major
intersections at Ch. 276+600.
 Visibility at junction location in approaches is a
safety requirement which is designed for junction
approaches and also maintained.
Sr No Chainage Type ofcurve Remarks
1 272+550 Summit 280 mt length
2 273+830 Valley 175 mt length
3 274+180 Summit 490 mt length

 Layout at intersections is channelized.
 Proper Sign boards are provided at location.
Super elevation: Super Elevation shall be limited to 7
percent, if radius of curve is less than desirable minimum
radius. It shall be limited to 5 percent, if radius is more than
desirable minimum and also at section where Project
Highway passes through an urban section or falls on amajor
junction. The super elevations provided at horizontal curves
are analysed and recorded.
Sr
No
Chainage
Super Elevation
Provided
1 Km. 270+154 5%
2 Km. 271+929 5%
3 Km. 274+506 -
4 Km. 274+938 5%
Vertical clearance at underpass: Vertical clearances
provided at underpasses are analysed and recorded
Sr
No
Underpass Location
Vertical Clearance
Provided
1 Km. 271+569 (VUP) 5.5 m
2 Km. 276+238 (VUP) 5.5 m
Horizontal clearance at underpass: Horizontal clearances
provided at underpasses are analysed and recorded
Sr
No
Underpass Location
Horizontal
Clearance Provided
1 Km. 271+569 (VUP) 25 m
2 Km. 276+238 (VUP) 25 m
6.CONCLUSIONS
Following conclusions can be made from the research;
 Geometric elements of road are well designed and
found in order as per requirements and guidelines
of standard specifications.
 Proper geometric design of roadsresultsinreduced
road accidents, comfort to road users, reduced
travel time and efficient traffic movement.
 The study would be helpful to examine the
geometry of highway and can be used to improveor
enhance the efficiency of road users.
 Additional care is required during design of
elements like intersections, horizontal curves,
vertical curves, etc.
 Previous studies have concluded that improper
design of geometric elements of roads results in
accidents, traffic congestions, uncomfortable
journey, etc.
 Geometric deign of highways is important factor to
construct a cost efficient, useful & safe
infrastructure.
REFERENCES
[1] IRC SP 84 2019- “Manual of Specifications & Standards
for Four Laning of Highways”.
[2] Hameed Aswad Mohammed ,04 July 2013. “THE
INFLUENCE OF ROAD GEOMETRIC DESIGN ELEMENTS
ON HIGHWAY SAFETY” (IJCIET).
[3] Vikas Golakoti (2015), “STUDY OF GEOMETRIC
FEATURES OF ROAD AND ACCIDENT RATE”.
[4] Yagmur ozinal, Islam Gokalp, Yigit Katanalp, Volkan
Emre Uz, 2019. “A literature review on design of
geometric elements of the roundabouts”.
[5] Council, F., and Steward, J.R., " Safety Effects of the
Conversion of Two-Lane Rural to Four-Lane Rural
Roadways Based on Cross-Sectional Models ",
Transportation Research Board Annual Meeting, 2000.
[6] Pankaj M. Thakare, Vipul S. Bawner, 2018. “Computer-
Aided Geometric Design of Road and Safety Evaluation
Using Vehicle Simulation Model”.
[7] Kuldeep Kalita, Akhilesh K. Maurya, 2019. “Probabilistic
Geometric Design of Highways: A Review”.
[8] Zhang Yingxue, "Analysis of the Relation between
Highway Horizontal Curve and Traffic Safety",
International Conference on Measuring Technologyand
Mechatronics Automation, China, 2009.
[9] Rishabh Chourasia, 2020. “Case Study on the Effect of
Geometric Design Consistency on Level of Safety for
Rural Roads under Indian Conditions”
[10] Ali Aram (2010), “Effective safety factors on Horizontal
curves of Two-Lane Highways” Journal of Applied
Sciences 10 (22), Malaysia, P.P 2814-2822, 2010.

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