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Kurdistan Journal of Applied Research (KJAR) | Print-ISSN: 2411-7684 – Electronic-ISSN: 2411-7706 | kjar.spu.edu.iq 

Volume 2 | Issue 3 | August 2017 | DOI: 10.24017/science.2017.3.33 

 

 

Flexible Pavement Evaluation: A Case Study  

 

 
 

  

 
 

 

Shamil Ahmed Flamarz Al-Arkawazi 

Building and Construction Engineering Department 
University of Garmian 

Kalar, Sulaimani, Iraq 

shamil.flamarz@garmian.edu.krd 
 

 

 
 

Abstract: This study is a survey to evaluate the flexible 

pavement conditions to determine and specify the types 

of the failures in the pavement for the selected 

highway. It is very significant to evaluate and identify 

the causes of the flexible pavement failures and select 

the proper and best treatment and maintenance type. 

The study had two major and critical goals which 

covered by considering the following three tasks; the 

first was the visual evaluation and inspection of 

existing flexible pavement conditions including the 

failures, the second to determine and find out the 

actual causes of these failures in the pavement, and  

the third is to select the most and effective treatments 

and maintenance types. As a case study, Khanaqin-

Kalar 2-way 2-lane rural highway was selected for 

evaluation and inspection purposes. The field 

evaluation works were achieved on the existing flexible 

pavement conditions of the selected rural highway. The 

results were most of the damages and failures in the 

pavement are serious and extreme surface deformation, 

cracks, disintegration, and surface defects. These 

damages and failures are caused by fatigue and other 

types of failures resulted from the movement of heavy 

vehicles and trucks, poor drainage design, unsuitable 

pavement layers thickness design, and improper 

pavement mix design and selected materials.      

 

Keywords: Flexible pavement, failure, deterioration, 

rural highway, evaluation survey. 

1. INTRODUCTION 

Ordinarily the term pavement only means the surface 

layer [1]. But in the designing of the highways, it means 

the pavement total thickness including wearing 

(surfacing) course, base course and sub-base course. It is 

hard and tough crust constructed over the natural 

subgrade in order to provide stable and leveled or flat 

surface for vehicles. It is a structure consist from 

overlies layers of materials over the natural subgrade 

which its primary and major function is to transfer and 

distribute the vehicles’ axle loads to the subgrade. The 

structure of pavement should provide acceptable riding 

quality surface, sufficient skid resistance and minimum 

noise pollution [2]. 

For designing purposes and depending on structural 

function and behavior, the road pavements types are 

generally divided or classified into two types: 

i. Flexible (bitumen) pavement. 
ii. Rigid pavement. 

Other pavement types include semi rigid or composite 

pavement and interlock (behartoon) cement concrete 

blocks pavement. These pavement types are less familiar 

than flexible and rigid pavement [1]. 

Flexible pavement design is the process and method of 

selecting the most effective and economical composition 

of flexible pavement courses or layers (taking in 

consideration the thickness of the pavement and type of 

selected materials) to fit the subgrade foundation. And 

cumulative traffic axle load to be carried and handled 

during the pavements’ design life. Flexible pavement 

structure design is different from building design and the 

bridges because of the fact that the design of pavement 

until today is based on semi-empirical or empirical 

method and there is no rationalistic design method. 

Flexible pavement design consists mainly from two steps 

or parts: 

1- Material mix design to be used in each layer of 
the pavement. 

2- Design the structure of the pavement (design 
the thickness of each layer with its component). 

The main and major factors to be taken in consideration 

in the flexible pavement design are: 

1- Traffic volume. 
2- Climate and weather conditions along the year. 
3- The road geometric design. 
4- Position. 
5- Soil or subgrade 
6- Drainage. 

Road maintenance is one of the significant components 

of the complete road system. Even if the highways are 

designed and constructed in a good way, they may still 

require maintenance, the range that will depend on 

several factors which include the type of pavement [3]. 

A flexible pavement consists from several layers of 

granular materials covered with bituminous material 

(waterproof), and as its name mean, it is considered to be 

flexible. The flexible pavement will bend (flex) under 

the applied load of the tyre. The objective of designing a 

flexible pavement is to avoid extreme flexing of any of 

the layers, failure or un-ability to achieve its cause over 

stressing of a layer, which finally will cause the failure 

of the pavement. In the flexible pavements, the 

distribution pattern of load changes from one pavement 

layer to another, because the strength of each pavement 

layer is different. The least flexible and strongest 

material is in the top layer and the most flexible and 

weakest material is in the lowest layer. The reason for 

that is at the surface the wheel load is applied over small 

area, the result will be high stress level, and deeper down 

in flexible pavement, the load will be applied over a 



 

 

larger area and the result will be lower stress levels, 

consequently enabling the use of less quality or weaker 

materials [4]. 

Pavement failure and deterioration process starts 

immediately after opening the road to vehicles (traffic). 

The process of failure and deterioration starts very 

patiently therefore it may not be noticeable, and over the 

time it get faster and accelerates at quicker rates. To 

minimize premature failure and deterioration, it is vital 

to implement the best method in planning, the designing, 

construction and maintenance of the highway or the 

road. It can be accomplished by testing and inspecting 

pavements that have early failed. The focus was to 

determine the causes of failure and deterioration in order 

to be prevented in the future. The biggest understanding 

of flexible failures which can be gained from detailed 

evaluation and investigation could be significant in 

reducing the costs related to pavement failures and 

deterioration in the future. In many cases the failure and 

deterioration of flexible pavement structure can be 

directly justified by insufficient maintenance and 

insufficient programs of evaluation. Under a limited 

budget it is very important to reduce and minimize the 

maintenance costs. For the mentioned purpose it is very 

important to consider and select a simple way or method 

for inspection (surveying) and evaluation of flexible 

pavement failures [5].  

Flexible pavement (bituminous) failure and deterioration 

generally occurs due to combined action of traffic 

volume and load, weather conditions and changes, 

drainage and environmental agent. Generally the flexible 

pavement fail and deteriorate at very fast rate when 

compared to rigid pavement because the mentioned 

above factors. Flexible pavements continue to fail and 

deteriorate at slow rate even without vehicles (traffic) 

movement on the flexible pavement surface as a result of 

the weather and environmental factors action. Rate of 

failure and deterioration of flexible pavement 

(bituminous pavement) rapidly increase when water is 

hold in the void spaces of the flexible pavement layers. 

Oxidation and aging of asphalt (bituminous) binder also 

lead to the failure and deterioration of the asphalt 

(bituminous) surfacing [1]. 

 

2. LITERATURE REVIEW 

Transportation system takes a special role in the 

economical development of any country. By the good 

transportation system means; comfortable, safe, rapid, 

and convenient, the people communication becomes 

possible and which is fundamental for various goods 

distribution in the country that is important and basic for 

its economic, industry and environment. The good 

highway system is very significant for the developing 

country to get the way to the modern society. In order to 

have good transportation system, various factors of 

failure and deterioration of the highway or road should 

be taken in consideration. Highway maintenance is very 

important for the traffic management as a whole. The 

various defects in the roads resulted from weak 

maintenance of transportation system are the main 

accident causes. Therefore a successful and good 

engineer is a person whose is not only able to design the 

highway or roads, but also have sufficient skills to 

maintain the highways and roads [6]. 

A flexible pavement (bituminous) failure and 

deterioration is defined by consistence of ruts, cracks, 

potholes, settlements, localized depression, etc. normally 

the localized depression is followed with rising in the 

proximity (vicinity). The sequence creates waves in the 

surface of the pavement. The failure or deterioration of 

any one or more of flexible pavement structure 

components creates the corrugation and waves on the 

surface of the pavement or rutting and shoving. 

Unleveled (unevenness) flexible pavement may itself 

consider as a failure and deterioration when it is 

excrescent. The flexible pavement failure and 

deterioration subject is considered to be complicated as 

several factors participate to its failure and deterioration. 

The oxidation and aging of asphalt (bituminous) films 

cause the failure and deterioration of flexible pavement 

(bituminous pavement). Destructive actions in flexible 

pavement are quickly increased when surplus water is 

retained in the flexible pavement void spaces [3]. 

Flexible pavement failure and deterioration can be 

considered as functional, structural, materials 

failure, and a combination of the mentioned 

factors. Structural failure and deterioration is 

losing the ability of carrying load, when the 

flexible pavement not any more able to absorb, 

transmit and distribute wheels load through the 

road structure without causing extra or more failure 

and deterioration. Functional failure is a boundary 

(border) term which may refer to the loss of any 

function of the flexible pavement such as structural 

capacity, skid resistance, and serviceability or 

passenger comfort. Material failure result from the 

loss or disintegration of material characteristics of 

any of pavement component materials [7]. 

Flexible pavement deterioration and failure is 

defined as a decreasing in the serviceability 

resulted from the development of surface failure 

and deterioration such as rutting, cracking and 

potholes [8]. It was reported that the highway 

engineers should look into the causes of flexible 

pavement (bituminous pavement) before going into 

the strategies of the maintenance. It was found that 

deterioration and failure of flexible pavement are 

resulted from combination or many of reasons. It 

has been noticed that only three factors; rutting, 

unevenness index and cracking are considered 

while other failures have been neglected while 

going to maintenance [5]. 

The major types of flexible pavement failures are 

failure of surface texture or deformation failure. 

Deformation failures and deterioration include 

rutting, shoving, depression, corrugation and 

potholes. These failures and deterioration may 

result from traffic volume (load associated) or 

environmental influences (non-load associated). It 

might reflect serious problems in materials or 



 

 

underlying structure that may cause cracking. 

Failure in the surface texture includes polishing, 

bleeding, cracking, raveling and stripping. These 

failures in the flexible pavement show that while 

the road pavement could be structurally sound, the 

surface is not functionally performing which 

designed for, which normally providing skid 

resistance, water tightness and smooth is running 

surface. Other various types of flexible pavement 

failures and deterioration include patching, edge 

defects and roughness [5]. 

The evaluation survey and assessment of the flexible 

pavement roads and highways is advantageous for 

transportation engineers because the reasons in the 

following: 

1- It gives and provides accurate reason of flexible 
pavement failure and deterioration which makes 

the maintenance works easy. 

2- Will provide good knowledge about flexible 
pavement failure and deterioration, which make 

the transportation engineers able to design and 

make high quality and performance roads and 

highways flexible pavement. 

3- Study the failure and deterioration of flexible 
pavement in specific area helps in improving 

the design of flexible pavement which can be 

more effective in term of safety, quality, and 

performance in the area. 

The objective of current study can be summarized in the 

following: 

1- Visual evaluation and inspection of existing 
flexible pavement conditions including the 

failures and deterioration. 

2- Determine and find out the actual causes of 
these failures and deterioration in the flexible 

pavement. 

3- Select the most proper and effective treatments 
and maintenance types.    

 

3. FACTORS EFFECTING AND 
INFLUENCING THE FLEXIBLE 

PAVEMENT PERFORMANCE 

The major factors that influencing the flexible pavement 

performance [4]: 

3.1. Traffic Volume and Load 
It is the most significant and influential factor effecting 

and influencing flexible pavement performance. The 

flexible pavement performance is mostly affected and 

influenced by the traffic load magnitude, loading 

configuration, and heavy vehicles load repetitions 

number.  

3.2. Moisture or Water 
Moisture is considerably and significantly affect the 

flexible pavement by weaken the natural gravel materials 

especially the subgrade support strength. Moisture or 

water enter the flexible pavement structure through holes 

and cracks in pavement surface, laterally (horizontally) 

through subgrade soil and from the water table 

(underlying) by the action of capillary. The results of 

moisture or water entry are lubrication of particles, 

interlock loss between the particles and later particles 

displacement which cause flexible pavement failure and 

deterioration. 

3.3. Subgrade Soil 
Subgrade is the flexible pavement underlying soil that 

support and handle the applied vehicles wheel loads. Too 

weak subgrade will fail to support and handle the 

vehicles wheel loads, which cause the pavement to flex 

extremely which finally cause the failure of the flexible 

pavement. If the flexible pavement designer not taking 

the difference in natural composition of subgrade soil in 

consideration, significant and important differences in 

the flexible pavement performance will be witnessed.   

3.4. Construction Quality
Failure to provide adequate compaction, inappropriate 

moisture content or conditions during the pavement 

construction, materials quality, and providing accurate 

flexible pavement layers thickness (after the compaction 

is finished) all mentioned conditions will effect directly 

on the performance of the flexible pavement. It is very 

important and significant to provide skillful staff, good 

and adequate inspection and a procedure of quality 

control during the construction works. 

3.5. Maintenance
Regardless how well the flexible pavement is built, it 

will start to deteriorate and fail over the time. The 

performance of flexible pavement depend on what type 

of maintenance, when to be done and how to be 

performed. 

 

4. TYPES OF FLEXIBLE PAVEMENT 
FAILURE OR DETERIORATION 

The common types of failure or deterioration in flexible 

pavement are classified in to the following four major 
groups [1]: 
i. Surface deformation 

 Corrugations 

 Rutting 

 Shoving 

 Shallow depressions 

 Settlement and Upheaval 
ii. Cracking 

 Fatigue Cracking 

 Transverse Cracking 

 Longitudinal Cracking 

 Edge Cracking  

 Reflective Cracking  
iii. Disintegration 

 Potholes 

 Patches 
iv. Surface defects  

 Raveling 

 Bleeding 
The common types of flexible pavement failure or 

deterioration and its expected or possible causes are 

listed in Table 1 [8] [3] [4]. 

 

 



 

 

 

Table 1: The common flexible pavement failure types 

and their expected or possible causes [3] [4] [8] . 

Failure Type Expected or Possible Causes 

Alligator 

cracking 

 Fatigue failure due to flexible/brittle base.  

 Inadequate pavement thickness.  

Block 

cracking 
 Reflection of joints cracking in 

underlying base.  

Longitudinal 

cracking 

 Reflection cracking.  

 Poor paving lane joint.  

 Pavement widening.  

 Cut/fill differential settlement. 

 Fatigue failure of asphalt concrete.  

Transverse 

cracking 

 Reflection of shrinkage cracking. 

 Construction joints.  

Rutting 

 Inadequate pavement thickness. 

 Post construction compaction. 

 Instability of base surfacing.  

Shoving 

 Poor bond between layers.  

 Lack of edge containment. 

 Inadequate pavement thickness.  

Depression 

 Settlement of service trench or 
embankment.  

 Isolated consolidation.  

 Volume change of subgrade  

Corrugation 
 Instability of asphalt concrete or base 

course.  

Edge drop 

 Inadequate pavement width. 

 Erodible shoulder material (lack of 
plasticity).  

Edge break 

 Inadequate pavement width. 

 Inadequate edge support.  

 Traffic travelling on shoulder edge drop.  

 Weak seal coat/loss of adhesion.  

Raveling 

 It is a result of insufficient adhesion 
between the asphalt cement and the 

aggregate. 

 Initially, a fine aggregate break loose and 
leaves small, rough patches in the surface 

of the pavement. 

Potholes 

 Potholes are often located in areas of poor 
drainage. 

  Potholes are formed when the pavement 
disintegrates under traffic loading, due to 

inadequate strength in one or more layers 

of the pavement, usually accompanied by 

the presence of water. 

Polishing 
Caused by traffic movement (vehicles 

movement). 

Patches 

 Filling the holes with asphalt concrete 
without cleaning and preparing and doing 

the required works for maintenance.   

 Filling the holes without doing proper 
leveling and compaction. 

5. METHODOLGY 

The deformation response of flexible pavements under 

traffic loading is characterized by recoverable 

deformations and permanent deformations. The 

permanent deformation is much smaller than the 

recoverable deformation and, as the number of load 

repetitions increases, the plastic strain due to each load 

repetition decreases. The deformation of materials is the 

result of three mechanisms: the consolidation 

mechanism (the change in the shape and compressibility 

of particle assemblies); the distortion mechanism 

characterized by bending, sliding, and rolling of the 

particles; and the crushing and the breaking of the 

particles occur when the applied load exceeds the 

strength of particles [9]. 

This study conducted to estimate and predict the flexible 

pavement road failure rate with particular references to 

cracking and other types of failures and deteriorations 

using available data. Data for the study was collected 

from related government departments (data related to the 

history of the selected highway and its construction) and 

an exploratory evaluation survey of the selected 

highway. The exploratory survey is a method employed 

in road performance modeling and is chosen in this study 

in order to scientifically evaluate the road. 

The adopted methodology is as follows: 

1. Identification and selecting the proposed study 
area. 

2. Review of the performance, behavior, failure 
and deterioration of flexible pavements 

exposed and subjected to traffic and local 

climatic conditions. 

3. Collection of relevant data from related 
government departments. 

4. Analyzing the collected data in order to create 
clear and scientific evaluation of the selected 

highway. 

5. Discuss the suitable and appropriate solutions 
based on the pavement failures and 

deteriorations.  

 

6. THE CASE STUDY AND STUDY AREA 

For the purposes of this study Khanaqin-Kalar 2-lane 2-

way rural highway selected. This rural highway is 

connecting Khanaqin City the center of Khanaqin 

District with Kalar City the center of Kalar District. The 

length of this rural highway is 33 Km of flexible 

pavement, and it is one of the very important highways 

because it is working as a connecting link between 

Diyala Governorate with Sulaimaniya and Kirkuk 

Governorates from the northeast of Iraq in addition to 

that it is leading to Iraq-Iran border (see Figure 1 and 

2). 

In 2005 Kurdistan Ministry of Rehabilitation and 

Housing\ Garmian Directorate of Roads and 

Transportation, established this 2-lane 2-way rural 

highway by repaving existing two sections (marked with 

red color in Figure 1) by new asphalt layer and 

connected them by constructing new section (marked 

with green color in Figure 1), and since then this 

highway is maintained only one time during its life but 

still suffering from severe types of failure and 

deterioration. 



 

 

Figure 1 Khanaqin-Kalar 2-lane 2-way rural highway 

route location (Google Map) 

 

 

Figure 2 Khanaqin and Kalar locations in the northeast 

of Iraq (Google Map) 

 

7. RESULTS OF THE EVALUATION  
SURVEY AND ASSESMENT 

As mentioned above Khanaqin-Kalar 2-lane 2-way rural 

highway, established in 2005 by Kurdistan Ministry of 

Rehabilitation and Housing\ Garmian Directorate of 

Roads and Transportation. This highway consists of 

three sections with the following information (see 

Figure 3): 

 Section 1: from Khanaqin city to Sauz-Balakh 
village (20 Km length). It was existed flexible 

part re-paved in 2005 with new layer of asphalt. 

 Section 2: from Sauz-Balakh village to Saleh 
Agha villages (8 Km length). It completely new 

construction in 2005. 

  Section 3:  from Saleh Agha village to Kalar 
city (5 Km length). It was existed flexible part 

re-paved in 2005 with new layer of asphalt. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 3 Khanaqin-Kalar rural highway three sections 

(Google Map) 

 

In order to determine and evaluate the existing 

conditions of the selected rural highway, a several field 

assessment survey conducted on the three sections of the 

highway. The results of the evaluation filed assessment 

survey showed that the pavement of this rural highway is 

suffering from the following types of failure and 

deterioration: 

 Rutting (see Figure 4) 

 Cracking (alligator cracking, block cracking 
and edge cracking) (see Figures 5, 6, 7, 8, 9, 

10, 11 and 13). 

 Potholes (see Figures 9, 10, 12 and 13) 

 Polishing (see Figures 9, 11 and 12) 

 Depression (see Figures 6, 10 and 11) 

 Raveling (see Figures 9 and 10) 

 Patching (see Figure 10 and 13) 

 

 

 

 

 

 

 



 

 

Figure 4 Rutting in the pavement of Khanaqin-

Kalar rural highway 

Figure 5 Severe blocking cracking failures in the 

pavement of Khanaqin-Kalar rural highway 

 

Figure 6 Severe Edge cracking and breaking, 

alligator cracking and depression failures in the 

pavement of Khanaqin-Kalar rural highway 

 

 

 

 

Figure 7 Severe edge cracking and breaking, block 

cracking, and alligator cracking failures in the 

pavement of Khanaqin-Kalar rural highway 

 

 

Figure 8 Edge and block cracking failures in the 

pavement of Khanaqin-Kalar rural highway  

 

 

Figure 9 Severe edge break and cracking, block 

cracking, alligator cracking, potholes, polishing, 

raveling and polishing failures in the pavement of 

Khanaqin-Kalar rural highway 

 

 

 

 

 

 

 

 

 

 

 



 

 

Figure 10 Severe potholes, raveling, alligator cracking 

Depression and bad patching failures in the pavement 

of Khanaqin-Kalar rural highway 

 

Figure 11 Polishing, Depression and alligator cracking 

failures in the pavement of Khanaqin-Kalar rural 

highway 

 

Figure 12 Polishing and pothole failures in the 

pavement of Khanaqin-Kalar rural highway 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 13 Bad patching, block cracking, alligator 

cracking, and pothole failures in the pavement of 

Khanaqin-Kalar rural highway 

 

 

The results of the evaluation survey and assessment for 

Khanaqin-Kalar rural highway total length and its three 

sections are illustrated in Table 2 and Figures 14, 15, 16 

and 17. 

 

Table 2: The results of the evaluation survey and 

assessment for Khanaqin-Kalar rural highway as a whole 

and its three sections 

Type of the 

Failure or 

Deterioration 

Percentage of the Damage in the Highway Based on 

the Failure Type (%) 

Section 1 

(20 Km) 

Section 2 

(8 Km) 

Section 3 

(5 Km) 

Total 

Length of 

the 

Highway 

(33 Km) 

Rutting 15 0 100 24.24 

Alligator 

Cracking 
27 5 0 17.57 

Block 

Cracking 
20 2 0 12.6 

Edge 

Cracking 
15 2 2 9.87 

Potholes 42.5 50 5 38.63 

Polishing 35 90 40 49 

Depression 30 1 1 18.57 

Raveling 20 50 0 24.24 

Patching 3 2 2 2.6 

 

 

 

 

 

 



 

 

 
Figure 14 The results of the evaluation survey and 

assessment for section 1 of Khanaqin-Kalar rural 

highway 

 

 

 

 
Figure 15 The results of the evaluation survey and 

assessment for section 2 of Khanaqin-Kalar rural 

highway 

 

 

 

 
Figure 16 The results of the evaluation survey and 

assessment for section 3 of Khanaqin-Kalar rural 

highway 

 

 
Figure 17 The results of the evaluation survey and 

assessment for the total length of Khanaqin-Kalar rural 

highway 

 

8. DISCUSSION 
The results of the evaluation survey and assessment 

showed that Khanaqin-Kalar rural highway suffer from 

several types of pavement failures or deteriorations. 

Each section of the three sections of the rural highway is 

evaluated separately, as sections 1 and 3 were existed 

parts and re-paved and section 2 was completely new 

construction in establishing Khanaqin-Kalar rural 

highway in 2005. 

The results of evaluation survey and assessment for the 

three sections of Khanaqin-Kalar rural high clearly 

indicated that there are number of severe failures and 

deteriorations in the pavement of these sections as in the 

following: 

I. Section 1: a significant percentage of the length 
and area of this section of the rural highway suffer 

from most of the types of pavement failure and 

deterioration (see Table 2 and Figure 14). The 

types of the failures with its percentages in section 

1 and the expected causes of the failures are listed 

in below: 

 Rutting (15% of section 1): the expected 
cause of this failure is in 2014 the highway 

used as alternative way by big number of 

traffic with heavy axel load resulted from big 

trucks, big trailers and military trucks and 

machines due to closing Kirkuk-Baghdad 

highway because of military operations (war 

against ISIS terrorist groups). The 

thicknesses of pavement layers of this section 

were not designed to carry such big number 

of traffic and heavy axel loads, therefore 

rutting failure occurred. 

 Alligator cracking (27% of section 1): the 
expected causes are fatigue failure and un-

adequate pavement layers thickness to carry 

un expected traffic loads (in 2014 the 

highway used by big number of traffic with 

heavy axel load resulted from big trucks, big 

trailers and military trucks and machines due 

to closing Kirkuk-Baghdad highway because 

of the military operations of the war against 

ISIS terrorist groups). 

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a

tc
h

in
g

24.24% 
17.57% 

12.6% 9.87% 

38.63% 

49% 

18.57% 
24.24% 

2.6% 

F
a

il
u

re
 o

r 
D

e
te

ri
o

ra
ti

o
n

 
(%

) 

Failure or Deterioration 



 

 

 Block cracking (20% of section 1) : the 
expected causes are hot mix asphalt 

shrinkage and daily temperature changing 

(cycling). Generally caused by un-ability of 

asphalt binder to expand and contract with 

temperature changes (cycles) because of 

asphalt binder (bitumen) aging. 

 Edge cracking (15% of section 1): caused by 
excess moisture resulted from bad drainage 

and lack of shoulders support due to weak 

materials. 

 Potholes (42.5% of section 1): In general, 
potholes are the final result of alligator 

cracking. As alligator cracking becomes 

severe, the interconnected cracks create small 

blocks of pavement which displaced as 

vehicles pass over them. The remaining hole 

after the pavement block is displaced is called 

a pothole. 

 Polishing (35% of section 1): caused by 
repeated big traffic volume on an aging 

flexible pavement. It can cause a dangerous 

low friction surface with a low skid 

resistance. 

 Depression (30% of section 1): caused by 
subgrade settlement resulted by insufficient 

compaction during construction or soft (poor 

quality) subgrade. 

 Raveling (20% of section 1): caused by 
inadequate adhesion between the asphalt 

(bitumen), filler and the aggregate. This type 

of failure typically occurs on an older 

pavement that has already oxidized, and it 

can be accelerated by the environmental 

conditions and traffic volume. 

 Patching (3% of section 1): resulted from bad 
maintenance, where the damaged or failed 

pavement to cleaned or removed in proper 

way before laying the new pavement and also 

the new pavement is not leveled and 

compacted in proper and standard way. 

 

II. Section 2: this section of the rural highway suffer 
from 8 types of failures (see Table 2 and Figure 

15), but in general most of the failures and 

deteriorations in this section are less severity than 

in section 1.  The types of the failures with its 

percentages in section 2 are listed in below:  

 Alligator cracking (5% of section 2) 

 Block cracking (2% of section 2)  

 Edge cracking (2% of section 2) 

 Potholes (50% of section 2) 

 Polishing (90% of section 2) 

 Depression (1% of section 2) 

 Raveling (50% of section 2) 

 Patching (2% of section 2) 
The causes of the failures and deteriorations in section 2 

are the same as for section 1 of the rural highway.  

III. Section 3: this section of the rural highway suffers 
from 6 types of failures (see Table 2 and Figure 

16). The percentages of 4 types of failures and 

deteriorations in this section are small (edge 

cracking, potholes, Depression and patching).  The 

types of the failures with its percentages in section 

3 and the expected causes of the failures are listed 

in below: 

 Rutting (100% of section 3): the expected 
causes of this failure are: 

- This section is carrying additional 
traffic which is going to and coming 

from Parwiz-Khan border point with 

Iran. All the additional traffic is 

heavy axel load vehicles (big trailers 

and truck).  

- In 2014 the highway used as 
alternative way by big number of 

traffic with heavy axel load resulted 

from big trucks, big trailers and 

military trucks and machines due to 

closing Kirkuk-Baghdad highway 

because of military operations (war 

against ISIS terrorist groups). The 

thicknesses of pavement layers of this 

section were not designed to carry 

such big number of traffic and heavy 

axel loads, therefore rutting failure 

occurred. 

 Edge cracking (2% of section 3) 

 Potholes (5% of section 3) 

 Polishing (40% of section 3) 

 Depression (1% of section 3) 

 Patching (2% of section 3) 
Except the rutting failure, the causes of the failures and 

deteriorations in section 3 (edge cracking, potholes, 

polishing, depression and patching) are the same as for 

section 1 of the rural highway. 

The result of the evaluation survey and assessment of the 

full length of Khanaqin-Kalar rural highway show that 

this rural highway suffers from serious problems. The 

pavement of this rural highway suffers from 9 types of 

failures and deteriorations (see Table 2 and Figure 17).  

 

9. CONCLUSION 
1- Most the types of the failures and deterioration 

were found along the Khanaqin-Kalar rural 

highway. 

2- The severity of the failures and deteriorations 
ranges from medium to high in the pavement of 

the rural highway. 

3- The major causes of the failures and 
deteriorations in the selected rural highway are: 

 Additional traffic volume with high axel 
loads which were not taken in 

consideration during designing the 

pavement layers thicknesses of the selected 

rural highway. 

 Poor or absent of drainage design. 

 Unsuitable pavement layers thickness 
design. 



 

 

 Improper pavement mix design and 
selected materials. 

4- The suggested maintenance or treatments are: 

 The highway shoulder improvement. 

 Removing the heavily damaged or 
structurally destroyed pavement and 

patching its places. 

 Overlying with new layer of asphalt 
pavement with adequate thickness.  

 

   

10. REFERENCE 

[1] M. T. Highway, T. Engineering, C. Engineering, 

and J. National, “Bituminous Pavement Failures 

Surajo Abubakar Wada,” vol. 6, no. 2, pp. 94–

100, 2016. 

[2] T. V Mathew and K. V. K. Rao, “Introduction to 

pavement design,” pp. 1–7, 2007. 

[3] N. G. Sorum, T. Guite, and N. Martina, 

“Pavement Distress : A Case Study,” vol. 3, no. 

4, pp. 274–284, 2014. 

[4] S. S. Adlinge and P. A. K. Gupta, “Pavement 

Deterioration and its Causes,” pp. 9–15. 

[5] M. M. E. Zumrawi, “Failures Survey and 

Evaluation of flexible Pavement Failures,” no. 

January, 2015. 

[6] C. Engineering, “Study on Failures and 

Maintenance of Flexible Pavement ( Pyay-

Aunglan – Koepin Portion ),” vol. 3, no. 14, pp. 

2984–2990, 2014. 

[7] W. R. Woods and J. W. A. Jr, “A General 

Characterization of Pavement System Failures , 

with Emphasis on a Method for Selecting a 

Repair Process,” vol. 7, no. 1, pp. 58–62, 2002. 

[8] P. Kumar and A. Gupta, “Case Studies on 

Failure of Bituminous Pavements,” 2010. 

[9] G. Tchemou, “Prediction of Flexible Pavement 

Degradation : Application to Rutting in 

Cameroonian Highways,” pp. 1301–1319, 2011. 

 

 

 

Biography 
Shamil Ahmed Flamarz Al-Arkawazi received the B.Sc. 

degree in Building and Construction Engineering in 

1999 and M.Sc. Degree in Highway and Airport 

Engineering in 2003 from Building and Construction 

Engineering Department- University of Technology-

Baghdad. He is assistant lecturer and his present 

occupation is Head of Building and Construction 

Engineering Department- University of Garmian.  

Author’s Google scholar page: 

https://scholar.google.com/schhp?hl=en&lr=lang_en&as

_sdt=0,5 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

https://scholar.google.com/schhp?hl=en&lr=lang_en&as_sdt=0,5
https://scholar.google.com/schhp?hl=en&lr=lang_en&as_sdt=0,5