A STUDY AND ANALYSIS OF SAFETY BARRIER UNDER INDIAN ROAD CONDITION

A Report Submitted in Partial Fulfillment of the Requirements for the Award of the Degree of

M. Tech

In

INDUSTRIAL SAFETY ENGINEERING

By

SACHIN Y JADHAV [211208004]

DEPARTMENT OF MECHANICAL ENGINEERINGNATIONAL INSTITUTE OF TECHNOLOGY

TIRUCHIRAPPALLI - 620015

DECEMBER 2009

BONAFIDE CERTIFICATE

This is to certify that the project “A STUDY AND ANALYSIS OF SAFETY

BARRIER UNDER INDIAN ROAD CONDITION”is a bonafide record of the work

done by

SACHIN Y JADHAV

[211208004]

in partial fulfilment of the requirements for the award of the degree of Master of

Technology in INDUSTRIAL SAFETY ENGINEERING of the NATIONAL

INSTITUTE OF TECHNOLOGY, TIRUCHIRAPPALLI,during the year 2009-2010.

N. SIVASHANMUGAM Dr. K .SANKARANARAYANASAMY

Project Co-Guide Assistant Professor Project Guide & Head of the Department

Department of Mechanical Engineering Department of Mechanical Engineering

National Institute of Technology National Institute of Technology

Tiruchirappalli-620015. India. Tiruchirappalli-620015. India

Project viva- voce held on _______________________

Internal Examiner External Examiner

ABSTRACT

For Indian Roads to control Future Problems associated with Road Accidents

there is a need to develop a widespread Risk Management system. Too often Road Safety

is treated a transportation issue, not a public Health Issue, and Road traffic injuries are

called “Accidents”, though most of them can be Prevented. Every Day 1, 40,000 or more

people are getting injured on worlds Roads. For India to Develop a Road Map of Success

Road side Safety Development Program would prove to reduce mortality Rates on Roads,

one of the Activity would include the Design of Road Restraint System. Designing

“Forgivable Roadside” is an important concept to promote Highway safety. Road side

barrier are meant to enhance safety of the Road Infrastructure and reduce the off –path

collisions.

For the Project work an assessment of related national and international literature was

studied regarding the nature of motorcycle collisions with road side crash barrier.

Various Design features of barrier systems were identified in the literature and safety

risk to fallen motorcyclist especially barrier post was studied. Approach towards Design:

Hazard is the main Factor of consideration for this Project. The solution is founded only

when Road Side Hazard can be removed.

It is founded from study that causes of hazard like Motor Vehicles; Object’s

like Poles, Trees, and Rivers etc cannot be removed. The Approach to control Hazardous

factor’s lies was only in barricading the Hazard. Guardrails are traffic barriers placed

along the road sides to protect hazards behind the Barriers. These guard rails are

constructed using standard steel W-Beam mounted on spaced posts. When the accident

involving motorcycles occur, the barrier post proves to be extremely dangerous causing

severe injuries to the motorcycle riders. In Order to reduce these injuries the Energy

Absorbing System was developed. This Protective device will be placed on the guard rail

post and would minimize the injuries and reduce the impact accelerations.

The study mainly focuses to come up with an Innovative Design for Road Side

Barrier so as to attenuate maximum impact force. Safety performance standard has been

upgraded to absorb maximum Kinetic Energy of Vehicles. The exposed barrier post is

guarded with Impact Attenuating Plate Designed using the Traditionally used New Jersy

Rigid Barrier Profile and a substitute for Distance spacer presently used(Damper) is

founded.

The Design Model was created using Catia V-5(R-9) Software using various modules

like Sheet Metal Design and Part Design .A Non Linear, static analysis is carried and the

deformation of post is studied at the initial stage of project .Finite Element Analysis

Software Abacus is used for Analysis of the Design. From the Analysis study it was

concluded that the final element model created were fairly Accurate to the Boundary

conditions for Post soil Interaction which opens the gates for the further Studies with

confidence. Based on the Indian Standards for Crash test (IRC-6-2000) & Guard rail

design and experimental details from literature review the designed model would be

validated. Later subsequent conclusions will be drawn after Analysis.

Keywords: Crash Barrier, Distance Spacer, Impact Attenuator, Design Modeling,Finite

Element Analysis.

ACKNOWLEDGEMENTS

I am greatly indebted & thankful to my Project guide Dr.K. Sankarnarayanasamy,

Professor, Department of Mechanical Engineering, National Institute Of Technology,

Tiruchirappalli(TN) and Co-Guide N. Sivashanmugam for providing all the facilities in

department for the successful completion of this project.

I sincerely thank Dr.S.P.Sivapirakasam(Asst.Prof), Dept of Mechanical

Engineering, National Institute of Technology, Tiruchirappalli, for coordinating &

motivating me in my project. I would like to express my gratitude to all those who gave

me the possibility to complete this thesis. I want to thank the Civil Department NIT-

Trichy(TN) for giving me permission to commence this thesis in the first instance, to do

the necessary study work and to use departmental data.

Above all I thank My Parents for their Love and Care and guiding me forever in

my Life.

SACHIN.Y. JADHAV

211208004

TABLE OF CONTENTS

Title Page No

ABSTRACT……………………………………………………………......i

ACKNOWLEDGEMENTS....................................................................... iii

LIST OF TABLE………………………………………………………… v

LIST OF FIGURES..................................................................................... vi

ABBREVIATIONS.................................................................................... viii

NOTATIONS............................................................................................. ix

1. INTRODUCTION……………………………………………… 1

1.1 Problem Definition................................................................ 1

1.2 Characteristic construction of crash barrier.......................... 2

1.3 Classification of Barriers……………………………….. 3

1.4 Performance of Barrier Types…………………………….. 7

2. LITERATURE REVIEW……………………………………… 8

2.1 Computational and Experimental Crash Analysis

of the Road Safety Barrier ……………………………..... 9

2.2 The Use of Finite Element Analysis in Road Hardware

Design by Malcolm H. Ray …………………………… 9

2.3 Simulations of motorist’s kinematics during impact

with W-beam guardrail …………………………………. 9

2.4 Crash worthiness Analysis of a Bridge Rail to

Guardrail Transition…………………………………….. 9

2.5 Standards for Crash Barrier Design…………………….. 9

2.6 Features of Barrier Design Impacting

Safety of Motorcyclist……………………………….. 9

2.7 Impact Attenuators …………………………………. 10

2.8 Indian Guidelines for Crash Barrier Design…………… 10

2.9 Manuel of Specification and Standards for

Four Laning of Highways (March 2008)………………… 13

2.10 Guidelines given by MOST……………………………… 15

TABLE OF CONTENTS

Title Page No

2.11 Barrier Guide (U.S. Department of Transportation)..... 15

3. DESIGN PROCEDURE…………………………………………. 21

3.1 Approaches towards Design……………………………….. 21

3.2 Procedure for Design & Development of

Road Side Barrier…………………………..…………….. 21

3.3 Development of New Barrier Design Modifying

Existing Barrier Design……………………….…………. 23

4. RESULT AND DISCUSSION …………………………. …… 35

5. CONCLUSION…………………………………………………. 38

6. FUTURE WORK……………………………………………… 39

7. APPENDEX................................................................................. 40

8. REFERENCES………………………………………………… 41

LIST OF TABLE

Table No Title Page No

2.8 Containment Levels as Per (IRC-6-2000)……………… 12

2.9.3 Flare Rates as per Manuel of Specification and

Standards for Four Laning of Highways in India

(March 2008)…………………………………………… 14

2.11.1 Technically exceptable Barriers,Normal Condition…… 17

2.11.2 Technically Acceptable Barriers, Primary Design Issue

(Aesthetics)………………………………………… 17

2.11.3 Technically Acceptable Barriers, Primary Design Issue

(Severe Conditions)………………...………………... 18

LIST OF FIGURES

Figure No Title Page No

1.1 Graphs for the Growth of Motor Vehicle Population

and Road Traffic Fatalities in India

(Source Ministry of Road Transport & Highways)…………. 1

1.3.1 Rigid Barrier (Concrete Barrier)……………………………. 3

1.3.2 W-Beam semi rigid barrier………………………………….. 4

1.3.3 Flexible Barrier……………………………………………… 6

2.11.2 Design Variables as per RDG Barrier Guide (U.S.A) ……… 19

3.3.1 Post Guarding Plate…………………………………………. 22

3.3.2 Distance Spacer……………………………………………... 23

3.3.3 W-Beam…………………………………………….............. 25

3.3.4 C-Post……………………………………………................. 26

3.3.5.5 Post guarding Plate(Iso metric view) ……………………… 27

3.3.5.8 W-Beam Assembled to Distance Spacer…………………… 29

3.3.5.9 Impact Attenuater covering Post………………………....... 30

3.3.5.10 Impact Attenuiating Plate Assembled to Post…………....... 31

3.3.5.13 Completed Assembly (Isometric View)………………….. 33

4.1 Strain Analysis of Post……………………………………. 36

4.2 Undeformed shape of Post…………………………………. 37

4.3 Deformed Shape of Post…………………………………… 37

ABBREVIATIONS

G1 Three-Strand Cable

HTC High-Tension Cable

G2 Weak Post W-Beam

G3 Box Beam

G4 Strong Post W-Beam

G9 Thrie-Beam

G9M Modified Thrie-Beam

CSS Concrete Safety Shape

SBL Steel-Backed Log Rail

SBT Steel-Backed Timber

PCG Precast Concrete Guard wall

SMG Stone Masonry Guard wall

RCW Random Rubble Cavity Wall

RDG Road Design Guide

FE Finite Element

MORT Ministry of Road & Transportation, India

IRC Indian Road Congress

NOTATIONS

R The horizontal force acting on the vehicle.

F Force.

g Gravity force of Vehicle Acting on Earth.

uR Sliding friction between the vehicle and the barrier.

v Approach velocity.

a Angle of the rail or cable relative to its original position.

h1 Effective Height of the Guard Rail greater than the center of

Gravity of vehicle.

h 2 Effective Height of the Guard Rail equal to the centre of

Gravity of vehicle.

Fe Ferrous

CHAPTER -1

INTRODUCTION

1.1 Problem Definition:

In India the car population as a proportion of total motor vehicles is much less

than in the HMCs (13% vs. 56-80%) and that the proportion of motorized two-wheelers

(MTW) much higher (70% vs. 5-18%). Using the epidemiological evidence from India

and other countries where better records are available, a conservative estimate can be

made that the ratios between deaths, injuries requiring hospital treatment and minor

injuries to be 1:15:70 in India. If the estimate of road traffic fatalities in India in the year

2000 is taken as 80,000, then the estimate of serious injuries would be 1, 200, 000, and

that for minor injuries 5,600,000. If we assume a 5% growth rate per year then the total

number of RTI in India in 2004 may be around 95,000-100,000 fatalities, 1,500,000

serious injuries, and7, 000,000 minor injuries. [1]It is founded that casualties associated

with motorcycle (2-wheeler) are more on Indian Roads .Thus it makes clear that there is a

need for developing a road map of success for India keeping in mind the vision for Road

Safety. The Figure below which clearly shows the Fatalities Rise is Proportionate to

Number of Vehicle Registered Yearly.

Fig: 1.1Growth of Motor Vehicle Population (Registered) and Road Traffic

Fatalities in India

(Source Ministry of Road Transport & Highways)

1.2 Usually a characteristic construction of crash barrier is as follows:

A Horizontal beam is bolted onto vertical support beams known as Post. This

construction is preferred and is been designed to stop a motor vehicle (car or truck) from

leaving the Road Lane and thereby preventing collisions with large objects like trees,

buildings, sign posts or preventing that the vehicle to fall into a water source such as

stream, river etc. To say in short, it is an object (guardrail) that will cause a small

controlled collision to prevent a larger uncontrolled one.

The crash barriers for Indian Roads have not been designed looking at safety

associated with motorcycles as well as looking at the proportion of motorcycle. During an

accident, a motorcyclist will fall off his or her bike and slide toward the crash barrier. At

this point, two things are common and can happen when dealing with a traditional crash

barrier design:

1. The person hits a Post: These Posts are most often metal I-beams-beams or sigma-

beams which will cut off the body part of motor vehicle occupant upon impact. The

person will then usually bleed to death. If the Post is founded to be an impacted dead-

center, high enough to cause death upon impact.

2. The person does not hit a Post: Here we have various possibilities which can happen.

a. The person slides underneath the barrier. With some luck, he will not hit the object for

which the crash barrier was erected in the first place.

b.The person slides into the void between the horizontal beam and the ground.

Depending on the space available, he she may get stuck and loose body parts.

c. The person may bounce off the horizontal beam because it’s very close to the ground.

This would be a hard and damaging impact, given the fact that the beam was designed to

withstand the impact of cars and trucks.

Thus motorcyclists and vehicles require two completely different approaches to design a

crash barrier; an alternative was made to favor the vehicles for obvious statistical and

safety reasons.

1.3 Classification of Barriers:

1.3.1 Rigid Barrier.

1.3.2 Semi Rigid Barrier.

1.3.3 Flexible Barrier.

1.3.1 Rigid Barriers:

Rigid barrier systems have the lowest deflection properties of the three types of

barrier systems, exhibiting very little, if any deflection on impact. Therefore, during a

collision, energy dissipation is achieved through deformation of the vehicle and rising

and lowering of the vehicle body. They are most suitable in locations where there is

limited space for barrier deflection and perform optimally in collisions where the impact

angle is 15° or less.

Concrete Barriers: Concrete barriers have been used for a considerable length of time,

although now their usage is generally being phased-out on high-speed roads, primarily

because the rigidity of the concrete results in peak deceleration rates which can result in

fatalities. Generally concrete barrier systems are made up of separate interlocking

sections joined together to make a rigid, continuous smooth surface. Traditionally, the

most common concrete barrier type used was the “New Jersey” barrier, however, more

recent variations on the design include the ‘F’ Shape, constant slope and vertical face

concrete barriers[3]. Usually, concrete barriers are mainly used for median barriers on

divided high-speed Roads. They are only suitable for low impact angles and they are not

suitable for placement away from traffic lanes. A further disadvantage is that even minor

scrapes can result in extensive damage to the vehicle bodywork. Limited success has

been achieved in introducing greater flexibility into concrete barriers by the incorporation

of reinforcing steel; this, however, has also created the new problem of how to repair the

barrier after impact.

Fig 1.3.1 Rigid Barrier (Concrete Barrier)

1.3.2 Semi-rigid Barriers:

Barriers based on a corrugated steel beam are the most common types. Semi-rigid

barrier systems have greater deflection properties than rigid systems, but still less than

those of flexible barrier systems. Redirection of vehicles following impacts achieved

through the transfer of energy to the support posts, spacer (Damper) and Rail. These

beams, of 10, 11, or 12 gauge steel, are corrugated longitudinally to give greater lateral

strength with a thinner section [3]. As well as giving a strong section the corrugations,

which occur most commonly as variants of a W -section, also increases the distance

between the impacting vehicle and the supporting posts.

W-Beam:

As the name suggests, W-beam guardrails have a ‘W’ profile that can be used

with a variety of post configurations depending on the particular characteristics of the site

for which the system is intended. They are not suitable for potential right angle impacts.

W-beam barrier systems are comprised of several components, including:

Fig 1.3.2 W-Beam semi rigid barrier

The W-beam rail, which must be strong enough to withstand the high axial,

tensile and bending stresses that occur in the event of vehicle impact.The posts, which

can be made of timber or steel and provide rigidity to the entire system. They also hold

the W-beam rail at the correct height.The blocks which prevent snagging of the posts

and aid in the prevention of vehicle roll-over by providing restraining forces above the

centre of gravity of the vehicle.The Spacer works for Energy transfer between Post and

Rail.

1.3.3 Flexible Barriers:

Flexible barriers also known as guard cable have the greatest deflection and

energy absorption properties of the three types of barriers, providing significant lateral

deflection and thus resulting in the lowest deceleration forces on vehicles, such as cars,

and their occupants. It consists of steel wire ropes mounted on weak post .Due to their

high lateral deflection properties; they are not used in situations where large defections

would result in contact with objects or oncoming vehicles. Cable barriers in various

forms have been in use for nearly 35 years as a means of easily and efficiently stopping

an out-of- control vehicle. [3]

The main advantage of flexible barrier is that, because of its great flexibility, a

cable can slowly decelerate a crashing vehicle and redirect it most easily along a path

parallel to the barrier. In addition, it is comparatively simple to fix the height of the

different cables so as to cater for the greatest number of the different vehicles in use

today. Care has to be taken, however, to ensure that the cable height is not so great that it

rides up over the bonnet of a small car, e.g. a sports car. They also have limited

effectiveness on the inside of curves and cannot be used on smaller radius curves.

Wire Rope Safety Barrier (WRSB):

Although there are slight variations in design, generally, WRSBs are comprised of

a three or four ‘woven’ rope system, which are fixed to frangible posts and the ends of

the wire Rope is fixed into the ground. The cables are made from galvanized steel, are

approximately 19mm in diameter and are held under tension. However, point to note is

that the concept of “frangibility” obviously depends on the characteristics (i.e. mass) of

the body impacting the post.

Fig 1.3.3 Flexible Barrier

Wire Mesh Fences (or Wire Meshed Topped Barriers):

Although not a conventional barrier system, wire mesh fencing, consisting of a

body of wire mesh usually supported by thin steel posts, has been identified in the

literature as being hazardous to motorcyclists when used in the same way as other barrier

systems. Such fencing may consist of various barrier bases that are topped with wire

mesh [3].

1.4 Performance of Barrier Types when Safety of Motorcyclists is considered:

This has been justified based on the following three arguments:

1. That the concept of redirecting the vehicle, namely the motorcycle, has little Meaning

in safety terms.

2. That any collision of the rider with any given rigid object will result in great trauma for

the motorcyclist.

3. Continuous surface could be expected to have a large impact on the safety

Performance where motorcyclist.

1.4.1 Factors considered for Energy Absorption:

Thickness of the Material.

Choice of the Material Hard or Soft.

Geometry of the metal plate which covers exposed guard rail post.

CHAPTER-2

LITERATURE REVIEW

2.1 COMPUTATIONAL AND EXPERIMENTAL CRASH ANALYSIS OF THE

ROAD SAFETY BARRIER

Z.Ren, M.Vesenak, Developed and evaluated a full scale computational model of

the Road Safety Barrier for use in Crash Simulation [5]. They Compared this model with

real crash test Data. The Impact Severity and Stiffness of the new design was evaluated

with Dynamic nonlinear Elasto-Plastic Analysis of the Three-Dimensional Road Safety

Barrier within the Framework of Finite Element Method. Validation of Model was done

from real Crash Test Data.

2.2 THE USE OF FINITE ELEMENT ANALYSIS IN ROAD HARWARE

DESIGN

Malcolm H. Ray, This paper reviews the history of the use of finite element

methods in roadside safety research and presents the current status of many of the

vehicle, occupant and roadside hardware models that have been developed to date. In his

study simple discreet element special purpose codes to predict gross deflections of

guardrails and bridge rails in collisions with motor vehicles [10]. More recently general

purpose nonlinear explicit finite element programs have been integrated into the analysis

and design of roadside safety hardware.

2.3 SIMULATIONS OF MOTORISTS KINEMATICS DURING IMPACT WITH

W-BEAM GUARDRAIL.

A.B.Ibitoye, A.M.S.Homouda, S.V. Wong, R.S.Radin studied the performance

standard required for guardrail system to be capable of capturing and redirecting a large

range of vehicle types and sizes but its effects on safety of motorcyclists are not yet

understood. [4] The paper describes a three-dimensional computer simulation of the

kinematics impact of motorcycle and dummy rider with W-Beam guardrail inclined at

angles 45 and 908 to the initial direction of travel. The simulation is based on the test

procedure recommended by ISO 13232 on the configurations for motorcycle–car impact.

The focus of this study is not on the motorcycle change in velocity, but on the rider’s

kinematics and acceleration vs. time history.

2.4 Crash worthiness Analysis of a Bridge Rail to Guardrail Transition

Ali.O.Athan, D.A.FBayton, R.Long, G.Fourlaris. (2007). in this study, a bridge

rail-to-guardrail transition is analyzed to fully evaluate its crashworthiness. A non-

linear, large-deformation finite element simulation program LS-DYNA is used for the

analysis. Previous study predicted that the transition was able to successfully contain and

redirect a 2000 kg pickup truck under NCHRP Report 350 test level 3 conditions. In this

study, the transition was subjected to 8000 kg single unit truck impact according to

NCHRP Report 350 test level 4 conditions. Both the model of 8000 kg truck and the

transition structure used in this study are acquired from previous successful studies.

Results of the simulation study showed that the transition structure found to be adequate

in containing and redirecting an 8000 kg truck. It was also determined that the post

impact trajectory of the truck, occupant risk values, article deflections and exit conditions

were very similar to those obtained from a similar transition structure crash tested under

test level 4 conditions. It was concluded that the finite element model of the vertical

flared-back bridge rail-to-guardrail transition is fairly accurate and can be used in further

studies with confidence.

2.5 STANDARDS FOR CRASH BARRIER DESIGN:

Manual of Specifications & Standards for Four- Laning of Highway’s-Planning

Commission: Government of India. March2008.

Barrier Guide for Low Volume and Low Speed Roads…….Publication

No.FHWA-CFL/TD-05-009…..By U.S Department of Transportation (Federal

Highway Administration)…. Chapter 4: Barrier Design and Placement.

2.6 FEATURES OF BARRIER DESIGN IMPACTING SAFETY OF

MOTORCYCLIST:

A review of the literature identified several barrier design issues which impact

upon Motorcycle rider safety. The literature suggests that the most dangerous aspect of

Guardrails with respect to motorcyclists is exposed guardrail posts. The guardrail posts

Present edges which concentrate the Impact forces, resulting in more severe injuries to

Motorcyclists. Usually Injuries on the Limb and Head are more common. This is a likely

problem for any barrier system that has exposed posts.

2.6.1 Other barrier features that are inherently dangerous to motorcyclists include:

The uneven edges of wire mesh fences, or wire mesh topped barrier systems

which provide numerous uneven surfaces, accentuating rider injury risk.Extremeupper

and lower Sharp edges of W-beam.Barrier systems that are too low as motorcyclists may

lead to jump over the barrier rail due to insufficient height leading to Injury if Impacted

with Post.Discontinuous barrier surfaces, such as Jersey barriers (Rigid Barriers) with

decorative designs, can be a cause of Hazard in Impact Conditions.

2.7 IMPACT ATTENUATORS:

Impact attenuators are designed to reduce the deceleration forces of an impacting

vehicle and may be either non-redirective or redirective. As disguised by its name, a non-

redirective impact attenuator is unable to redirect an impacting vehicle back into its

intended direction, but rather functions by absorbing the kinetic energy of the vehicle on

impact. A redirective attenuator has both energy absorbing properties to slow vehicles

that hit the attenuator head-on, as well as being able to redirect impacting vehicles back

into their original direction when hit on an angle.

2.8 INDIAN GUIDELINES FOR CRASH BARRIER DESIGN:

Indian Road Congress (Code-6-2000): [2]

The Semi Rigid Barrier suffer Large Dynamic Deflection of Order of 0.9 to 1.2m

(Containment level), on impact where as the rigid concrete type suffer comparatively

Negotiable Deflection. The Efficiency for the two types of Barrier is established on basis

of Full scale Crash test.

Table 2.8 Containment Levels as Per (IRC-6-2000)

Category Application Containment

P-1:Normal Containment Bridges Carrying Expressway

or Equivalent

1.5 Ton Vehicle at 110Km/Hr

and 20 Degree Angle of

Impact

P-2:Low Containment All Other Bridges Except

Bridge Over Railway

1.5 Ton Vehicle at 80Km/Hr

and 20 Degree Angle of

Impact

P-1:High Containment At Hazardous and High

Locations over Busy Railway

Lines.Etc

30 Ton Vehicle at 60Km/Hr

and 20 Degree Angle of

Impact

2.9 MANUEL OF SPECIFICATION AND STANDARDS FOR FOUR LANING

OF HIGHWAYS (MARCH 2008)

2.9.1Barrier Warrants: [2]

The longitudinal roadside barriers are basically meant to shield two

types of roadside hazards i.e. embankments and roadside obstacles and

also for preventing the vehicles veering off the sharp curves. The barrier

is not warranted for embankment having a fill slope of 3: l or flatter. The

warrants for roadside objects are mainly dependent upon the type of

obstacle and the probability of their being hit. A barrier shall be installed

only if the result of vehicle striking the barrier is likely to be less severe

than the severity of accident resulting from the vehicle impacting the

unshielded obstacle. Some of the commonly encountered roadside

obstacles are bridge piers, abutments and railing ends, roadside rock

mass, culverts, pipes and headwalls cut slopes, retaining walls, lighting

supports, traffic signs and signal supports, trees and utility poles.

2.9.2 Road Side steel barriers: [2]

Design Aspects: The "W" beam type safety barrier consists of steel

posts and a 3 mm thick "W" beam rail element which is spaced away

from the posts. The spacer minimizes vehicular snagging and reduces

the likelihood of a vehicle vaulting over the barrier. The steel posts and

the blocking out spacer shall both be channel section of 75 x 150 mm

size and 5 mm thick. The rail shall be 700 mm above ground level and

posts shall be spaced 2m center to center. The thrie beam safety

barrier shall have posts and spacers similar to the ones mentioned

above for "W" beam type. The rail shall be placed at 850 mm above

the ground level. This barrier has higher initial cost than the "W" beam

type but is less prone to damages to vehicle collisions especially for

shallow angle impacts. The "W" beam, the Thrie beam and the posts

spacers and fasteners for steel barriers shall be galvanized by hot dip

process.

End treatment for steel barrier: An untreated end of the roadside

barrier can be hazardous, if hit, because the barrier beam can

penetrate the passenger compartment and cause the impact vehicle to

stop abruptly. End treatments should, therefore, form an integral part

of safety barriers and the end treatment not spear vault or roll a

vehicle for head on or angled impacts[2].The two end treatments

recommended for steel barriers are "Turned down guardrail and

Anchored in back slope”.

Turned down guardrails have the "W" or Thrie sections reduced

from full height to ground level with a gentle slope over a distance of 8

to 9 meters. The turned down rail is intended to collapse on impact

allowing the vehicle to pass over it without becoming airborne or

unstable. In order to locate the barrier terminal away from the traveled

way and to minimize drivers' reaction to a hazard near the road by

gradually introducing a parallel barrier installation or to transitional

roadside barrier nearer the roadway such as a bridge parapet or a

railing, the turned down shall be flared away from the roadway.

Suggested flare rates depending upon the design speed and type of

barrier are given in Table Below.

2.9.3 Flare Rates: [2]

Table 2.8.3 Flare Rates

Design Speed In Km/Hr Flare Rates Flare Rates

Rigid Barrier Semi- Rigid Barrier

100 17:1 13:1

80 14:1 11:1

65 11:1 9:1

50 8:1 7:1

40 8:1 7:1

30 8:1 7:1

The posts in the end treatment should have the same cross sections

as provided in the main barrier. At road cross sections in cutting or if the

road transitions from cut to fill, the safety barriers can be anchored in

back slopes. The back slope covering the anchored portion of the barrier

should be graded flat with side slopes preferably not steeper than 10:1.

The anchored portion should develop a tensile strengthen the rail element

to prevent the rail from pulling out of the anchorage. The barrier can also

be anchored in an earth beam specially constructed for this purpose

provided the new beam itself is not a hazard to the traffic. The earth

beam should be made impervious to erosion.

Placement: Placement recommendations determine the exact

layout of the barrier and shall be made by the design engineer keeping in

view the lateral offset of the barrier and flare rate. The final layout shall

be a site-specific combination of these factors. The barriers shall be as far

away from the traffics possible and shall preferably have uniform

clearance between the traffic and the hazard. As far as possible the safety

barrier shall be placed beyond 2.5 m of the traveled way. For long and

continuous stretches, this offset is not critical.

The distance between the barrier and the hazard shall not be less than

the deflection of the barrier by an impact of a full sized vehicle. In case of

embankments, a minimum distance of 600 mm shall be maintained

between the barrier and the start of embankment slope of a hazard to

prevent the wheels from dropping over the edge.

2.10 GUIDELINES GIVEN BY MOST: [6]

Metal Beam Crash Barrier shall generally be located on approaches to Bridge

structures at locations where the embankment height is more than 3 meters, and at

horizontal curves. It is suggested that the following Criteria be used.

2.10.1 For Roads where cars travel in excess of 50km/hr:

1. At >3meter drops where the slide slope is 2:1 or steeper.

2. At >1 meter drops at sharp bends (defined as those where the safe speed to

negotiate the bend is more than 20km/hr lower than the speed on the approach)

where the slide slope is 2:1 or steeper.

3. Where there is a Risk that Vehicles could fall into a body of Water Deeper than

600mm.

4. To Shield any Solid, substantial object within 5 meters of the carriageway.

5. On Medians Less than 9 meters wide where the road has an ADT of >20000.

2.11 BARRIER GUIDE (U.S. DEPARTMENT OF TRANSPORTATION): [3]

For Low Volume and Low Speed Roads.

Publication No: FHWA-CFL/TD-05-009 November 2005

2.11.1 BARRIER SELECTION:

Selection of the most appropriate barrier system for the conditions at a specific site

involves the following steps:

2.11.1.1 Identify special selection issues.

Normal selection issues include costs, maintainability, repair, barrier size, dynamic

deflection and available end treatments. At times, however, one of two other issues may

be very important:

a. Aesthetics: [3]

Aesthetics of a barrier system may be more important than the cost of the system.

There are two aesthetic issues to consider. First is the appearance of the barrier itself.

Barriers are available that have rustic appearance that may be compatible with park and

forest settings.

Because some of these barriers are considerably more expensive than conventional

barriers, their selection may affect the barrier warrant. Some barriers are less obstructive

than others.

b. Severe Conditions.

A large percentage of heavy trucks, high frequency of severe crashes and other

significant safety concerns may be the overriding issue in some situations.

2.11.1.2 Determine the design speed. If the design speed is not known, it is acceptable

to use the posted speed. However, it may be appropriate to use the operating speed if the

actual speeds exceed the design or posted speeds. Operating speed is usually defined as

the 85th percentile speed in free flow conditions. The operating speed can be obtained

through a traffic engineering study and can be approximated by driving with free flowing

traffic.

2.11.1.3 Determine the hazard offset. The hazard offset is the distance between the

hazard closest to the roadway and the edge of the traveled way. The hazard offset must

allow adequate room for a barrier to be constructed and the dynamic deflection of the

barrier system. This issue is most important for hazards that protrude above the ground

such as trees and other fixed objects.

2.11.1.4. Identify technically acceptable barriers. Tables below provide guidance for

the identification of technically acceptable roadside barriers, using the primary design

issue, design speed and available hazard offset. All barriers found in the selection tables

are crashworthy and are technically acceptable alternatives for the selected conditions of

speed and hazard offset.

Table 2.11.1 Technically exceptable Barriers,Normal Condition.

Table 2.11.2 Technically Acceptable Barriers, Primary Design Issue (Aesthetics)

Table 2.11.3 Technically Acceptable Barriers, Primary Design Issue (Severe

Conditions)

2.11.1.5 Select the most appropriate barrier: [3]

The following issues should be considered when selecting the most appropriate barrier

from the technically acceptable list:

a. It is appropriate to restrict barrier types in order to simplify maintenance and minimize

the number of spare parts that must be stocked.

b. Cost is normally the overriding issue.

c. If aesthetics is a concern but not the overriding issue Table 2.10.2 can used, with

aesthetics as one of the other selection criteria. However, if aesthetics is more of a

concern than cost, Table 2.10.3 should be used, which will restrict consideration to

barriers designed for aesthetics or to minimize view obstruction.

d. Ease of maintenance.

e. Safety performance. Generally, barriers with more deflection result in less vehicle

damage upon impact.

f. Available end terminals and transitions, if needed. A barrier must be placed so the

hazard is outside the dynamic deflection distance and to allow enough room for the

construction of the barrier itself. These factors are included in the minimum barrier –

hazard offset.

2.11.2 Design Variables: [3]

Below Figure Shows the Variables that are considered in the RDG Design Process.

Fig 2.11.2 Design Variables as per RDG

LA is the lateral distance from the edge of the traveled way to the back of the

hazard.

LC is the clear zone width, measured from the edge of the traveled way. LC serves

as a check on LA. It is not necessary to shield a hazard beyond the clear zone, so

LA does not have to be greater than LC.

L3 is the lateral distance from the edge of the traveled way to the front edge of the

Hazard.

L2 is the offset of the roadside barrier, measured from the edge of the traveled

way to the front face of the barrier. The designer must select the barrier offset.

Factors to consider in selecting L2.

LR is the run out length, measured longitudinally from the upstream extent of the

hazard along the edge of pavement. LR is the stopping distance off the pavement.

LS are the shy line offset. Rigid objects such as roadside barriers close to the

pavement tend to intimidate drivers, causing them to slow down or shift

positions. This may result in a loss in capacity that can be a concern for high

volume roads. Although it is preferable to locate barriers at or beyond the shy line

offset, it is seldom an important factor for low volume conditions.

2.11.3 Principles of Crash Barrier Design:

Ideally a crash barrier fence should present a continuous smooth face to an

impacting vehicle, so that the vehicle is redirected, without overturning, to a course that

is nearly parallel to the barrier face and with a lateral deceleration, which is tolerable to

the motorist.

To achieve these aims the vehicle must be redirected without rotation about both

its horizontal or vertical axis (that is, without’ spinning out’ or overturning), and the rate

of lateral deceleration must be such as to cause the minimum risk of injury to the

passengers.

2.11.3.1 Lateral Rotation:

Consider a vehicle of mass m is colliding with the barrier at an angle. The

horizontal forces acting on the vehicle are the normal reaction of the barrier R, which

tends to turn the vehicle anti- clockwise and F + uR which tends to turn it clockwise.

The sliding friction between the vehicle and the barrier is represented by uR, and

F is the average value of the other forces produced by, for example, striking posts or

other obstructions.

If the barrier is to fulfill its function of redirecting the vehicle parallel to the safety fence,

then the net effect of the moments of these forces must be clockwise. This condition is

given by

F+J1R x <- R Y

crose - b sin fJ <

c sin fJ + b cos fJ

Thus it can be seen that if F or uR is large, the condition may not be satisfied and the

vehicle may spin out of control with a clockwise rotation.

When tan = c/b, the vehicle will spin out from the barrier, regardless of the value of F +

uR For a typical car the value of this critical angle is about 70 deg. If, however, F = 0

(i.e. the vehicle does not strike any posts), then for u = 0.01 (steel on steel) and u = 0.3

(steel on concrete).

It is seen that as long as the impact angle is kept below 54 deg. for a concrete barrier and

64 deg. for a steel barrier, then spin-out will only occur if considerable retardation is

imparted to the vehicle by posts or other barrier components. To ensure that retardation is

small however severe the impact is, barrier posts should be made weak in the direction of

the line of the barrier.

2.11.3.2 Lateral Deceleration:

While an impact is taking place the barrier will deflect and the vehicle will

crumble to a certain extent. If it does not bounce off or climb but instead swings and

scrapes along the barrier, then the centre of gravity of the vehicle will move through a

total lateral distance of (y - b + d), where ‘d’ is the sum of the deflection of the barrier

and the lateral crumpling of the vehicle.

The most important quantity from the point of view of the motorist is the average lateral

deceleration of the vehicle; this is given by

(v sin lJ)2

2[c sin lJ +b( cos lJ-l)+d]

Where ‘v’ is the approach velocity.

This equation is actually a reflection of the risk of injury to the motorist. Death can result

if the human body is subjected to excessive deceleration, and the amount which he can

withstand is in turn influenced by whether or not he is wearing a safety harness.

If the barrier consists of a rail or cable with supporting posts, the tension in the barrier is

given approximately by (ma T= - 2 sin X Where) ‘a’ is the angle of the rail or cable

relative to its original position.

2.11.3.3 Overturning:

If the vehicle is assumed to be a rigid body, the principal vertical forces acting on it.

The vehicle will tend to overturn if (ma (h1-h2)>>m*g*b) and a >~ h1 - h2

Hence if the effective height of the guard rail is equal to or greater than the centre of

gravity of the vehicle, then the vehicle cannot overturn.

CHAPTER 3

DESIGN PROCEDURE

3.1 Approaches towards Design

Hazard is the main Factor of consideration for this Project. How the Road Side Hazard

can be removed.

Causes of Hazard:

Motor Vehicles.

Road side object’s like Poles, Trees, Rivers etc.

Over speed of Vehicles. Speed can’t be reduced too much extent in this Fast

living world.

The Approach was only in barricading the Hazard Present along the road side.

3.2 Procedure for Design & Development of Road Side Barrier:

Barrier Design Criterion and Guidelines:

Barrier Design Criterion and Guidelines are considered as per “Manuel of

Specification and Standards for Four Laning of Highways (Planning Commission

Government of India)-2004”.

The Analysis would be carried as per specification mentioned in Indian Road

Congress (IRC-6-2000) Code for Semi Rigid Barriers for different Containment

Level’s.

Problem’s identified in Currently Used Crash Barriers in India.

Among the Motorcyclist Impact, rider among motorcycle crashes, rider impacts

with barriers, particularly barrier posts, are a serious concern in terms of the

potential for serious injuries to Head or Limb.

The Presently designed Barriers are not properly designed to retain riders .It is

usually found During Accidental condition that the motorcyclist pass through,

over or under the barrier.

The main reasons for considering this aspect were:

It is realistic approach to expect that if a barrier has been installed, there is always

some sort of serious hazard beyond the barrier. Therefore, for retaining and

redirecting should protect the motorcyclist from the hazardous environment

beyond the barrier.

3.3 Development of New Barrier Design Modifying Existing Barrier Design:

3.3.1 Post Guarding Plate:

The Profile of Post Guard Plate resembles the New Jersey Barrier. The Profile

Design Prevents the Rider Form Direct impact to the Post of the Barrier. Thus

preventing the Rider from Severe injuries.

The smooth surface prevents the unlikely sliding or falling of motorcyclist

(having got separated from their bike) way through/under the barrier system.

The Design helps in retaining and redirecting the rider by protecting him/her from

the hazardous environment beyond the barrier.

It decelerates the speed of the Vehicle after impact within acceptable limit.

Suitable to be placed at critical location’s where severity of motorcyclists

skidding is more.

Fig 3.3.1 Post Guarding Plate

3.3.1.1 Dimensions:

Thickness : 3mm.

Height : 500mm.

Overall Length : 4500mm.

No of Threaded Holes on Plate : 6

Pitch Diameter : 12mm.

Depth : 3mm.

Minimum Distance between Post and Post Guarding Plate Facing Road : 75mm.

Maximum Distance between Post and Post Guarding Plate Facing Road : 235mm.

3.3.1.2 Material Properties (As Per MORT)

Should conform to IS 5986 Gr.Fe 360(ST-37)/Fe 410(ST-42) Fe 510(ST-52)

Galvanized to 550 gm /mt².

3.3.2 Distance Spacer:

Shape: Parallelogram shaped Hexagonal Structure.

The parallelogram shape of spacer helps in taking the forces in proper Direction in

Impact Condition’s of Motorists.

Fig 3.3.2 Distance Spacer

3.3.2.1 Key Points of Hexagonal Cross Section:

It can absorb (or dissipate) high impact energy via irreversible mechanical

process, E.g.-Plastic Deformation.

It should satisfy pre determined requirement, such as amount of Energy

Dissipation, Load and Space Limitation.

It should undergo Nonlinear Deformation.

It should sustain ultimate constant load in Impact Process.

Should Occupy Less Space.

3.3.2.2 Dimensions:

1. Height : 150mm.

2. Width : 105mm.

3. Length : 180mm.

4. Thickness of cells : 2mm.

5. Material : Aluminum.

3.3.3 W-beam:

"W" Beams are very effective in absorbing the energy of impact, providing the

redirection of the vehicle and reducing the severity of accident.

Effective to any type of Post Either Sigma, C-Post, Wooden post etc

It helps in sharing the Impact forces between Vehicle and Post. The Extreme ends of

W-beam are Bended inwards toward the Post so as to prevent the injuries to the

rider along the Beam thus providing smooth surface at extreme ends.

Fig 3.3.3 W-Beam

3.3.3.1 Dimension:

1. Length of Beam : 4500mm

2. Thickness : 3mm.

3. Height : 330mm.

4. No of Holes for Bolts : 3.

3.3.3.2 Material Property :( As per MORT)

1. Hot tipped Galvanized to 550gms/m².

2. Yield strength: 255 N/mm².

3. Tensile Strength: 410-520 N/mm².

4. Elongation:15-25%

5. Cold Rolled Formed Section.

6. Raw Material conforming to IS 5986 Gr.Fe 360(ST-37)/Fe 410(ST-42)Fe

510(ST-52)

3.3.4.1 Posts:

Height of the Post is an important consideration especially when rider hit the

barrier while still on the motorcycle and there is a Hazardous Environment on the

other side of the barrier (Ex: Trees, River, Railway Tracks, Pit etc) and is more

prone to fall in Hazardous side Crossing over the Barrier.

Fig 3.3.4 C-Post

3.3.4.2 Dimension:

1. Cut Section : C-shape.

2. Height : 1900mm

3. Width : 100mm.

4. Length : 55mm

5. Thickness : 5mm

6. Holes on Each Post : 3

3.3.4.3 Material Property (As per MORT):

1. Cold Rolled Section.

2. Hot tip Galvanized to 550 gms/m².

3. Raw material conforming to IS 5986 Gr.Fe 360(ST-37)/Fe 410(ST-42)Fe

510(ST-52)

4. Yield strength: 210-235 N/mm².

5. Tensile Strength: 360-410 N/mm².

6. Elongation: 18-30%.

3.3.5 Other Designs (Using CatiaV-5, Modeling Software):

Fig 3.3.5.5 Post guarding Plate(Iso metric view)

The Post guarding plate plays the role of Guarding Post and Vehicle Occupant

during accidental condition. It is designed using Sheet Metal Design Module of

Catia.

The Profile Resembles the New Jersey type median Rigid Barriers.

Fig 3.3.5.6 W-Beam(Iso Metric view)

Fig 3.3.5.7 Distance Spacer

Fig 3.3.5.8 W-Beam Assembled to Distance Spacer

From the above Design it is seen clearly that the Sharp extreme ends of the W-

Beam are Bended inwards so as to prevent Injuries to the Motorcyclist when came

in contact.

Fig 3.3.5.9 Impact Attenuater covering Post

Concept Design to Cover the Exposed Post so as to absorb Kinetic Energy of

Motorcycle hitting the Post so as to prevent majorly the Seveare Head or Limb

Injuries.

Fig 3.3.5.10 Impact Attenuiating Plate Assembled to Post

Concept to Design a Impact Attenuiating Plate which helps in two ways first to

cover the Post aswell as redirect the vehicle for steep angles.

Fig 3.3.5.11 Complete Assembly(Side View)

Fig 3.3.5.12 Guard Rail (Dimensioning)

Fig 3.3.5.13 Completed Assembly (Isometric View)

The assembly Design shows that the post and distance between two conseequtive

post is Covered by Post Guarding Plate(Impact Attenuator).

Thus the Design proves to be a safety model for the Motorists under Impact

Conditions with the Guardrail.

Fig 3.3.5.14 Completed Assembly (Side View)

CHAPTER 4

RESULT AND DISCUSSION

4.1 ANALYSIS

4.1.1 Approaches for Analysis of Designed Model:

Crash simulations using finite element models had been emerging as a means to conduct detailed

analyses of crash or impact events. The objective of this study was to develop a viable finite

element (FE) model for the standard w-beam guardrail system and compare it with an available

Finite Element vehicle model in crash simulations to examine the effects of design variations on

the safety performance of traditional w-beam guardrail systems.

The study involved three steps. In the first step, detailed representations of all components

were made to ensure that the model was an accurate representation of the actual system. The

second step involved validations of the model by comparisons of simulated results to data from

previously conducted full-scale crash tests. The third step involved using the validated model as

the basis for studying the effects of w-beam guardrail design variations .W-beam were

represented as piecewise, linear, plastic materials. Models of this material have been extensively

utilized to represent structural metals and have been fully optimized. The material behavior is

isotropic, elasto-plastic with strain rate effects and failure. The properties used for these materials

were taken from literature (MORT Specifications).

First, the explicit geometry of all components was incorporated in the model. This

included the w-beams & posts. This ensured that the correct mass, inertia, and stiffness of

the different parts were reflected in the model. The soil and Post interaction behavior was

studied by applying suitable Boundary conditions at the end of post using Abaqus

software. This Finite element analysis program uses an explicit LaGrangian numerical

method to solve three-dimensional, static, nonlinear, large displacement problems. The

properties used for this model were back-calculated from data obtained from the literature

for specific types of soil condition like loose soil, gravel condition etc. Simulations of

these tests were performed and the material properties were varied until suitable needed

deformations in post were obtained .The results showed that the post of thickness 5mm

was suitable to except maximum load condition up to 1.3 Ton on impact with post.

Property of Material:

• Material-Steel.

• Young's Modulus -200 GPa.

• Poison’s Ratio-0.3

• Density(Kg/cubic m)-7830

• Tensile Strength: 410-520 N/mm2.

• Yield strength: 255 N/mm².

Fig4.1 Strain Analysis of Post

The Strain Analysis Graph shows that the C-Post can with stand maximum load i.e.

up to 1.3 tons under vehicle impact at steep angular conditions. Thus the C-Post

design suits the conditions for the thickness of material (5mm) for the newly designed

crash barrier.

Fig4.2Undeformed shape of Post

Fig4.3 Deformed Shape of Post

As per the IRC Specifications maximum Deflection (Containment Level) allowed for

Post is 1.2m the Deformed Shape results showed that the deflection is within the

specified limit.

CHAPTER 5

CONCLUSION

A Non Linear, static analysis is carried and the deformation of post is studied at the

initial stage of project .The Element type used for the analysis was a Regular

Tetrahedron. Finite Element Analysis Software Abaqus is used for analysis of the Design.

The results showed that the post of thickness 5mm was suitable to bear maximum load

condition up to 1.3 Ton on impact with post. From the Strain Analysis study it was

concluded that the final element model created were fairly accurate to the Boundary

conditions for Post soil Interaction which opens the gates for the further studies with

confidence.

CHAPTER 6

FUTURE WORK

• Validation of the Model:

1. To obtain the Impact Deformation of the System(Guard Rail) for Different Load

hitting at the same angle at Similar Locations for the Crash Barrier Designed.

2. To obtain the Impact Deformation of the System(Guard Rail) for Different Load

when hitting at the Different Angle of Impact.(Angles from 8 Degree to 20

Degree).

3. To obtain the Impact Deformation of the System(Guard Rail) for Different Load

hitting at the change in angle at same Locations for the Crash Barrier Designed.

4. To obtain the Impact Deformation of the System(Guard Rail) for Different Load

hitting at the Different Angle of Impact at Different Locations.

5. To Change the Shape of the Damper which would Deform More and thus Reduce

the Compressive Load coming on the Post.

6. Modification’s in the Design of Impact Attenuator Designed for Guard Rail.

APPENDEX

Programm Code for Analysis:

No of Elements (*Element, type=C3D4): 3184

No of Nodes (*Node): 5169

Referances

1. Dinesh Mohan (2004) The Road Ahead: Traffic Injuries and Fatalities in India –

Transportation Research and Injury Prevention Program. Indian Institute of

Technology-Delhi.

2. INDIAN GUIDELINES FOR CRASH BARRIER DESIGN: Indian Road

Congress (Code-6-2000) Manual of Specifications & Standards for Four- Laning

of Highway’s-Planning Commission: Government of India (2008)

3. BARRIER GUIDE for Low Volume and Low Speed Roads. Publication No:

FHWA-CFL/TD-05-009 (U.S. Department of Transportation.)(2005)

4. A.B.Ibitoye, A.M.S.Homouda, S.V. Wong, R.S.Radin Simulations of Motorists

kinematics during impact with W-Beam guardrail. Road Safety Research Centre,

Advances in Engineering Software 37 (2006) 56–61

5. Z.Ren, M.Vesenak, Computational and Experimental Crash Analysis of the

Road Safety Barrier. Engineering Failure Analysis 12 (2005) 963–973

6. Guidelines given by MOST (Ministry of Shipping and Transportation)(2001)

7. Ali.O.Athan Crash worthiness Analysis of a Bridge Rail to Guardrail

Transition.Mustafa Kemal Accident Analysis and Prevention(2007)

8. Rebecca Smith a, Lawrence J. Cook, Lenora M. Olson, James C. Reading,

Trends of behavioral risk factors in motor vehicle crashes. Intermountain Injury

Control Research Center, The University of Utah ( 2002) 249–255

9. Thesis: Design of Crash Barrier. (Prof.K.Bhaskar- Civil Department NIT-Trichy).

10. Simulation of motorcyclist’s kinematics during impact with W-Beam guardrail

A.B. Ibitoye, A.M.S. Hamouda, S.V. Wong, R.S. Radin Road Safety Research Center Advances in Engineering Software 37 (2006) 56–61