Project

1. INTRODUCTION
1.1 General Background
The civil engineering department of Khwopa engineering college affiliated by Purbanchal University has offered a project work to the student as a part of course in the fourth year second part of bachelor degree. In this project, four students were involved as per rule of the department. The “ “ under full bridge consultancy (P) Ltd in kathmandu Metropolitans was chosen as our project work. The proposed road is one of the important road which act as diversion road from ………………to………..and from ……………..to……………...

Due to importance given to this road consultant purpose this road as standard of feeder road and this criterion has been considered for the design of geometric parameters of the said road project.

2.2 Objectives of the project
The main objective behind the offering of this project work is to consolidate and update our theoretical and practical knowledge of engineering in the actual field so that one can build up one’s confidence and experiences in the related field. In addition to this, it develops a kind of team spirit and co-ordination for the long-term work with the environment.
Ø To provide a good access to……..
Ø To provide an access to different rural settlement with a minimum construction and maintenance cost.
Ø To enhance the use of locally available resources in terms of labors, materials and finances and improve access to services, market and trading centers.
Ø To generate huge amounts of direct and indirect employment in order to uplift the living standards of people.
Ø To practice the construction of local rural road through local government with people’s participation in a socially responsible manner.


1.3 Technical Support
Full bridge consultancy has provided us the entire technical requirement per our need in the Detail survey and design. It is a company dedicated with software which is named as SW-software. This software is totally used in the design of the road .there is two software within it i.e.SW_DTM and SW_road 2004.

1.4 Study Team:
The endorsements of our knowledge and spiritual wetness made
This project in the completion phase. The co-ordination, understanding and co-operation between us are the success of this project.


SCOPE OF WORKS:


2 Literature Review

2.1 Historical Development of Road Construction
Obviously, Nepal is a small and one of the developed countries situated in roughly east-west direction. Over 75% of its land mass is hills and mountains ranges, spreading North-south within a horizontal distance of 200 km between 50m to over 8,800m above sea level and expanding about 900km from East to West. The Himalayas of Nepal provide an extraordinary refuge to an extremely rich and unique biological as well as ethnic and religious cultural diversity.
Nepal is a mountainous country where majority of rural population does not have road links from the cities to their village. Local transportation depends on the foot trails and mule trucks. The government’s Department of Roads (DOR) constructs the roads in the country but the pace of construction is very slow as compared to the national need. A total of 15905 km of road has been recorded in census 2001 which include 4617 km blacktopped, 3959 graveled and 7329 Km earthen road. DOR classifies 4 types of roads in the country as:
Ø National Highways (NH)
Ø Feeder Road (FR)
Ø District Road(DR) and
Ø Urban Road or city Road (CR).
National highways with links different regions of Nepal whereas the feeder roads link national highway with the district headquarters. District roads connect the villages and urban centers and also connect them to the district headquarters. Urban or city roads serve the city area. According to the latest policy on construction of roads, the DOR is responsible for NH, FR and sometimes district roads. But district road construction responsibility has been transferred to the district development committee office.
The following tables show road statistics for the different development region of Nepal.



Development Regi Road km Population Area Popln/km km/sq km



Eastern Region 3410 5286890 28456 1550 .12


Central Region 6343 7988612 27410 1259 .23

Western region 2709 4571013 29398 1687 .09


Mid-Western Region 2106 2707244 42378 1285 .05


Far-western Region 1337 2183175 19539 1633 .07


National Total/Average 15905 22736934 147181 1430 0.11
Type of Road Road length (km) Road Category Length



BT 4617 NH 2974


GR 3959 FRN 1649


ER 7329 FRO 171



DR 9060


UR 2051


Total in Nepal 15905 Total in Nepal 15905




Source: Nepal Road statistics, 2000

2.1.1 Geometric Standards
Ø Geometric design of the highway is one of the important aspect which deals with visible dimensions of the road way. Thus, it is the design of those elements with which the highway users is directly concerned. Setting out of various geometric design standards has its significance for appropriate design of longitudinal and cross profiles of the road construction. Appropriate geometric design standard will provide smooth, safe, easy and economical vehicular operation and reduced drainage and maintenance problems.
Geometric design of highways deal with following elements:
i) Cross section element:
In this, the considerations for the width of pavement, formation and land, the surface characteristics and cross slope of pavement are included.
ii) Sight distance considerations:
The sight distance or clear distance visible ahead of a driver at horizontal and vertical curves and at intersections govern the safe movement of vehicles.
iii) Horizontal alignment details:
The change in the road directions are made possible by introducing curves. Super-elevation is provided by the outer edge of pavement to counteract the centrifugal force developed on a vehicle traversing a horizontal curve; extra pavement width is also provided on horizontal curve.
iv) Vertical alignment details:
The gradients and vertical curves are introduced in the vertical alignment of a highway.
iv) Intersection elements:
The design of road intersections facilities for safe and efficient traffic movement needs adequate knowledge of traffic engineering.
While designing the geometrical elements we have to keep in mind the following basic considerations.
Ø The design should be safe and efficient both during day light and at night and also in good and bad weather.
Ø The design should be suitable for the traffic volume both daily and at peak hours and also for the future anticipated traffic.
Ø The design should be consistent, complete and should confirm to the design speed and vehicular characteristics.
Ø The maintenance cost should be as minimum as possible
The main objective of the geometric design is to provide proper function of the suitable gradients, curves (both horizontal and vertical alignments), cross-sectional elements of road such as width of carriage way, shoulders, median strips distances as well as lateral and vertical clearance each of which will be described in detail in the subsequent units.
As far as practicable, standards adopted in the design of this project have kept in accordance with the Nepal Road Standard (NRS) 2027. References as per IRC have also been followed in many portion of design.
2.1.1.1 Design controls and criteria
The geometric design of highways depends on several design factors. The important of these factors which control the geometric elements are:
i) Design speed:
The design speed is the most important factor controlling the geometric design elements of highways. Design of almost every geometric design element of a road is dependent on the design speed. Nepal Road Standard (2027) has given different design speed according to the terrain and vehicles types
ii) Topography:
Topography is the main element which directly influences the geometric design of the road significantly. Nepal Road Standard (2027) has classified into following according to percent cross-slope of the country.
class
Terrain type
Percent cross slope
1
Plain
0 to 10
2
Rolling
>10 to 25
3
Hilly / Mountainous
>25 to 60
4
Steep
>60

iii) Traffic factors:
Vehicular characteristics and human characteristics of road users are the factors that affect the geometric design of highways.
iv) Design hourly volume and capacity:
The traffic flow or volume keeps fluctuating with time, from a low value during off-peak hour to the highest value during the peak hour. The reasonable value of traffic volume is decided for the design and this is called the design hourly volume.
v) Environmental and other factors.
The environment factors such as aesthetics, landscaping, air pollution, noise pollution and other local conditions should be given due consideration in the design on road geometric.

2.1.1.2 Road Classification
According to the NRS-2027, Road in Nepal shall be classified into four categories:

National Highways
National Highways are main highways connecting East to West and North to South of the Nation. The Roads connecting National Highways to Regional Head –quarters shall also be classified as National Highways. These serve directly the greater portion of the longer distance travel, provide consistently higher level of service in terms of travel speeds and bear the inter community mobility ( regional interest ) . These roads shall be the main arterial routes passing through the length and breadth of the country as a whole.

Feeder Roads
Feeder roads are important roads of located nature. These serve the community’s wide interest and connect District Head-quarters and/or Zonal Head-quarters to National Highways.


District Roads
This class of roads consisting of all roads not defined as National Highways or Feeder and City Roads, serves primarily by providing access to abutting land carrying little or no through movement. These roads should give access to one or more villages to the nearest marker or to higher types of roads. Moderate travel speeds are typical on such roads.

City Roads and Streets
These include roads within the urban limits except for the above classes, passing through the city. These provide access to abutting residential, business or industrial properties.

2.1.1.3 Design Speed
The design speed is the main factor on which geometric design elements depends which is maximum approximately uniform speed that will be adopted by the majority of the drivers. It is the basic parameters and a key factor which determines all the other geometric features. The sight distance, radius of horizontal curve, super-elevation, extra-widening of pavement, length of summit and valley vertical curve are all dependent on the design speed which depends on the class of road and terrain. The adoption of design speed for this type of road is 40 km/hr as per NRS 2027.

2.1.1.4 Horizontal curves
A horizontal curve is a curve in plan to provide gradual change in the direction of the center line of a road. For safe and smooth vehicular operation on curves, the following provisions have been made in the design.
Ø Minimum radius of curve
Ø Super elevation
Ø Extra widening
Ø Setback distances

Minimum radius of curve
The Minimum radius of horizontal curve is governed by design speed. The basic relationship used for finding the minimum radius of curvature is that the centrifugal force is balanced by the combined effects of the super elevation and slide friction and is given as:
Rmin = V2/ (126.5(e + f))
Where, V = Design Speed
e = Super elevation
f = Co-efficient of friction between the road surface and the tyre
Maximum value of super elevation (e) and co-efficient of friction between the road surface and the tyre that can be adopted are 7% and 0.15 respectively.

For minimum radius (theoretically) of curve
Rmin=402/126.5(0.07+0.15) =57.26 m
But with several constraints (residential areas, availability of land) the minimum radius of 12.5 m is recommended as per NRS 2027. But in difficult places it has been limited up to 10 m.

Super elevation
In order to counteract the effect of centrifugal force and to reduce the tendency of the vehicle to overturn or skid while they transit a horizontal curve, the outer edge of the pavement is raised with respect to the inner edge, thus providing a transverse slope through out the length of the horizontal curve. This transverse inclination to the pavement surface is known as super elevation, or cant or banking. The amount of outer edge raised is expressed either by the decimal fraction of ‘m’ of rise per meter of horizontal cross section or in percentage which is called super elevation or cant.

Following relationship can be used for finding out the super elevation.
e +f = V2/126.5R
Where, e = super elevation
V = design speed = 40 Km/hr
R = radius of curve
f = Co-efficient of friction between the road surface and the tyre
Super elevation should not be less than that required for proper drainage of water from the surface of the road. Thus, a minimum value of super elevation equal to camber slope has been provided at curves of large radii it provide necessary drainage for surface water. The maximum super elevation provided for horizontal curve has been limited up to 7%. If the value of ‘e’ is greater than 7% then reduction in design speed is necessary recommended keeping at 7%.

Extra Widening
Extra width of pavement is provided for psychological reasons such as, to provide for greater maneuverability of steering at higher speeds, to allow for the extra space requirements for the overhangs of vehicles and to provide greater clearance for crossing and overtaking vehicles on the curves. So it is very important in pavements with more than one lane. Extra widening includes psychological widening and mechanical widening.
Thus,
We = Wm + Wps
Where, We = total extra widening
Wm = mechanical widening = nl2/ 2R
Wps = psychological widening = V/9.5√R i.e. We = nl2/2R + V/9.5√R

Set back distance
Set back distance is the requisite site distance that should be available from the center line of road across the inside of horizontal curves to ensure the required sight visibility while transiting these curves. It is the distance measured perpendicular to center line of curve at mid point of curve by which the obstruction like walls, cut sloped, trees, fences, buildings, wooded areas, high farm crops etc. are set back to provide for meeting the visibility requirement in transiting the curves.
The alternatives that must be taken into consideration are:
a) When length of curve is greater than sight distance, i.e. (L>S)
M = S2/8R
M = Set back distance
R = Radius of curve
S = Requisite site distance
b) When length of curve is less than sight distance, i.e. (L L, L= 2S-(500+3.5S)/A
Where the centripetal acceleration rules, V=Speed in Kmph
L= AV2/395

2.1.1.6 Sight distance
Sight distance available from a point in curve is the actual distance or length of road up to which the driver at his seat from a specified height above the carriageway can visualize any moving or stationary objects clearly so as to avoid unwarranted accidents such as danger of head on collision and facilitate overtaking.

Stopping sight Distance
Stopping sight distance is the distance covered by a vehicle from the instance a danger is comprehended by the driver to the actual stop. The absolute minimum sight distance is therefore equal to the stopping sight distance, which is also sometimes called non-passing sight distance. It depends upon the perception time of the driver, brake efficiency of the vehicle, gradient or slope of the road. Stopping Sight Distance (SSD) can be computed as:
SSD = 0.278*V*T + V2/254*(f A 0.01n)
Where, f = co-efficient of longitudinal friction
n = gradient, percent
V = design speed: km/hr
T = total reaction time: 2.5 sec
As per NRS 2045 the minimum SSD provided for design speed of 40km/hr is 45 m.

Overtaking Sight Distance
Overtaking Sight Distance is the distance measured along the center of the road which a driver with his eye level 1.2 m above the road surface can see the top of an object 1.2 m above the road surface in the opposite direction.
The relationship for calculation of OSD is given by
O.S.D. = 0.2798Vbt + 0.27987VbT + 2S + 0.2798VT
Where, Vb: Speed of overtaken vehicle, km/hr.
t: Reaction time of driver, 2 sec
V: Design speed, km/hr
T = √ (14.454S/A)
Where, S: Spacing of vehicle (0.7Vb + 6)
A: If acceleration of overtaken vehicle is not given, it can be assumed to be 16 km/hr less than the design speed.


2.1.1.7 Right of Way
Right of Way is the area of land acquired for the road along its alignment. The width of this acquired land is known as land width and it depends on the importance of the road and possible future development.

A minimum land width has been prescribed for each category of road. The commended land width for different class of urban roads are, 50 – 60m for arterial roads (high type of urban roads meant for through traffic, with controlled access), 30 – 40m for sub-arterial roads, 20 – 30m for collector streets (urban roads and streets meant for collecting traffic from local streets and feed to the arterial roads) and 10 – 20m for local streets

2.1.1.8 Camber
Camber is the convexity provided to the cross-section of the surface of carriage way with the purpose of draining out the surface water in the longitudinal drain and is expressed in percentage. As per NRS 3% and 7% cambers are provided respectively for bituminous road surface and gravel shoulder respectively.

2.1.1.9 Passing Zones
Passing zones are provided in roads for safe, easy and clear passing of vehicles. These zones are essential in dense cities and in one-lane roads. Generally, three passing zones are to be provided in 1km length of road. These serve as an overtaking zone or temporary stop for vehicles.

2.1.1.10 Lateral clearance:
According to per N.R.S for culverts, the full roadway width shall be carried through including the width of the shoulders. For minor and medium bridges, minimum width between kerbs shall be one half metres greater than the approaching pavement width. The width between railing or trusses shall be increased beyond the kerbs by the least one half meter on each side. On all trunk roads and other roads requiring a two lane carriesway, the bridge shall be designed for a two lane carriesway with necessary widenings as above.

2.1.1.11 Vertical clearance:
AAccording to per N.R.S, the minimum vertical clearance for through structures shall be 4.75 m. Overhead wires, poles etc shall be least 7.0 m above the road surface.

2.1.1.12 Traffic Signs & Sign Posts
Traffic Signs & Sign Posts are very much important in roads, as it is very difficult to meet all the geometric and other engineering standards in the actual field. Adequate sign posts should be erected to indicate road constraints, monuments delineator speed restriction, sharp bends men at work trail crossing point and so on whose provision must be confirmed according to the standards of DOR, Nepal. The sign should be erected such that they can be easily seen and recognized by the road users. Commonly used signs are classified into three categories viz.
Regulatory signs
Warnings signs &
Informatory signs

Regulatory Signs
Regulatory Signs also known as mandatory signs are meant to indicate the road users an obligation to comply with statutory laws, regulations, prohibitions and violation or non-compliance of which is considered a legal offense.

Warning Signs
Warning Signs are used to convey the road users of certain hazardous condition such as dead ends level crossing & ferry, steep slopes, rough road, zigzag, hair pin bend etc. that exist on or adjacent to the roadway. The warning or cautionary signs are in the shape of equilateral triangle with its apex pointing upwards, consists of a white background, red border and black symbols.

Informatory Signs
Informatory Signs are used to guide the users along routes; inform them of destination and their respective distance to make travel easier, safe and pleasant.

Distance sign:
The standard designs for 1 kilometer and 5 kilometer posts issued separately by the department of roads shall be followed on all roads.
2.1.1.13 General:
Drainage
Provision for road side drains and cross drains should be made as necessary.
Parapets and Guard rails:
In hilly and mountainous roads, parapets and guardrails should be provided as per standards to be issued by the department of roads.
Tree plantation:
In rural areas, trees shall be planted on either sides of the roads. In case of urban roads, trees or hedges shall be planted as and where possible.

2.1.1.13 Hair Pin Bend
Hair pin bend is a compound curve in a hill road which changes its direction through an angle of 180° as so under same side down the hill. The curve confirms the shape of hair pin so it is called hair pin bend. A hair pin bend is located on a hill side having the minimum slope and maximum stability. It must be safe from view points of landslides and ground water.


2.1.1.14 Survey Stages
The survey stages include following steps:
Map survey
Topographical map is studied to note different contour interval and main features of line like river, hill, valley and approximate location of bridge site.

Reconnaissance survey
It is second stage of survey for highway location to examine the general characteristic of the area. Only simply instrument like abney level, clinometers, barometers, etc. are used.

Preliminary survey
This is done for various alternative alignments. All necessary physical information and features of topography, drainage and soil are obtained in this survey.

Detail survey
After the preliminary survey, the alignment finalized at the design office. Then detail survey should be carried out for collecting information to prepare the plan, construction design for the highway project.

2.1.1.15 Factors to be considered During Survey
For designing the alignment, following factors should be considered:
Ø Obligatory points
Ø Traffic
Ø Geometric design
Ø Economy
In hill roads additional care has to be given for:
Ø Stability
Ø Drainage
Ø Geometric standards
Ø Other considerations

Obligatory points:

There are control points governing the alignment for the highways. These control points may be divided broadly into
Two categories:

i) Points through which the alignment is to pass
ii) Points through which the alignment should not pass

Traffic:

The alignment should suit traffic requirements. Origin and Destination study should be carried out in the area and desire lines be drawn showing the trend of traffic flow.

Geometric design:

The geometric design factors such as gradient, radius of curve and sight distance also would govern the final alignment of the road. If straight alignment is aimed at, often it may be necessary to provide very steep gradient.

Economy:

The alignment finalized based on above factors should also be economical. In working out the economics, the initial cost, maintenance and vehicle operation should be taken into account.

Stability:

While aligning hill roads, special care should be taken to align the road along the side of the hill which is stable. A common problem in hill roads is that of land slides. The cutting and filling of earth to construct roads on hill-side cause steeping of existing slopes and affect its stability.

Drainage:

Numerous hill-side drains should be provided for adequate drainage facility across the road.

Geometric standard of hill roads:

Different sets of geometric standards are followed in hill roads with reference to gradient, curve and speed and they consequently influence the sight distance, radius of curve and other related features.

Resisting length:


The resisting length of a road may be calculated from the total work to be done to move the loads along the route taking the horizontal length, the actual difference in levels between the two stations and the sum of ineffective rise and fall in excess of floating gradient. The resisting length of the alignment should kept as low as possible. Thus the ineffective rise and executive fall and executive fall should be kept minimum.

Geometric Standard summary:
a) Carriages way width 3.50 m
b) Shoulder width 0.5 m
c) Formation width 4.5 m
d) Right of way 30 m(15m on each side)
e) Camber 4%
f) Shoulder cross slope 5%
g) Design speed 40 km/h(Absolute minimum 25km/h)
h) Minimum radius on Horizontal curves 10 m
i) Maximum average gradient 7%
j) Maximum gradient 12%
k) Minimum gradient 1.0%
l) Maximum length of grade in excess of average gradient 12

m) Maximum length of recovery at grade
Specified 150m@3%
n) Minimum length of vertical curve 20 m
o) Maximum super elevation 12%
p) Minimum super elevation 4%


























3 Computer Aided Design:
3.1 A Historical Prospective
Conceived during 1957, the first CAD system was actually developed only during the 1960's. Dr. Hanratty is widely known as "the Father of CAD/CAM" for his pioneering contributions to the field of computer aided design and manufacturing. While at General Motors, Dr. Hanratty was co-designer of DAC (Design Automated by Computer), the first production interactive graphics manufacturing system.

Another notable contributor to the computer graphics industry during this period was Dr. David Evans and Ivan Sutherland, who founded Evans and Sutherland in 1968. In 1970's focused on automating 2D drafting. The key here was placing lines and circles on a computer screen and automating the process by using a macro/programming interface. During this period, CAD designers not only had to be good drafters, but they also had to be good programmers.

One of the most exciting things that happened during this era was the advent of the personal computer and the beginning of Autodesk. John Walker, genius programmer and visionary founded Autodesk in 1982. He and his small band of original thinkers set off to develop five different desktop automation applications. They did this with the notion that one of the applications would take off. They would then band together behind the winner and develop it further. That product turned out to be AutoCAD

3.2 Review of Available Commercial Road Design Software
Road Design Software recently came into use in the world due to its commercial benefits that has gain the popularity by serving the consumers. The popular road design softwares in the world according to the commercial aspects are:


3.2.1CivilCAD 2004/Roads
CivilCAD 2004/Roads, Sivan Design's flag ship product, is one of the leading softwares in the world for roads design. With easy to install capabilities, ample design options, quality drawings and reports production, and cost-effective qualities - CivilCAD 2004/Roads is setting new standards for the global Roads Design CAD software market. Roads contractors, Earthworks and Land Development Contractors using the software, all acknowledge CivilCAD 2004/Roads as their primary tool for getting the job done.


3.2.2 HighRoad
The main design object of HighRoad is automatically maintains complex relationships in a network of intersecting roads. Each road automatically adjusts itself to match changes in other roads that it connects to. This extends not only to the obvious plan relationship but also the vertical grading of the roads, how they interconnect and the interaction between cut and fill batter slopes in an intersection.

HighRoad produces a full set of plan/profile drawings for you - automatically orienting each plan view to fit nicely on the drawing sheet. The drawing manager synchronizes drawing production with design by establishing a drawing layout that is automatically updated throughout the design process.

3.2.3 Bentley MXROAD
Bentley MXROAD is an advanced, string-based modeling tool that enables the rapid and accurate design of all road types. With MXROAD, you can quickly create design alternatives to build the “ideal” road system. After a final design alternative is selected, you can automate much of the design detailing process, saving time and money.

Intersection design, along with other functionality in MXROAD, is string-model based. This allows you to dynamically re-grade intersections as needed. Problem areas can be resolved during the design phase rather than incurring the high cost of rework onsite.

3.2.4 Softree
Softree has been providing high quality software for surveying, mapping and engineering for more than 15 years. More than a 1000 companies in North America use this software internationally for applications in the natural resource and land development industries.

3.3 Application of Computer Aided Design of Road Works in Nepal
In Nepal, the construction of road was started not more than a century and use of road software in road design is recently introduced. In 1986, Naubise-Muglim highway (82 Km) was designed by Scott Wilson using MX Road Software (Moss System). Then 1992, Second Road Improvement Project was launched by Hyundai which used the same Moss System. In 1996, Third Road Improvement Project (127 KM) was launched by Scott Wilson in which SW-Road software was used for the first time. And in 1997, Damak Ring Road was designed by using SW-Road software which help in gaining its popularity.

Between 1998-2000, the various projects were assigned by using SW-Road software which covered about 600 KM. Due to its efficiency and cost optimization, a group of civil engineers working as private consultants felt the need to uplift the use of software among the engineering community of Nepal and hence establishment of an Engineering Software Company was conceived in early 1998, but it came to reality on February 2000, when it was formally registered with Department of Industries.

In 2001, the company designed 67 KM access road for Melamchi Water Supply Project under the NORPLAN A.S. Company. After then within 2003 – 2005, the software is recognized commercially all over the country. Presently 40 firms are using this SW-Road Software for the efficient designing of road.

3.4 Advantages of Computer Aided Design of Road Works
With easy to install capabilities, ample design options, quality drawings and reports production, and cost-effective qualities – road software is setting new standards for the Roads Design CAD software market. Roads contractors, Earthworks and Land Development Contractors using the software, all acknowledge CAD as their primary tool for getting the job done.

Computer Aided Design of Road Works takes a quantum leap in productivity through the use of various softwares and hence results in the optimization of design. CAD has gained the popularity because of the following advantages:
· User friendly and easy to use
· Easier training to the Engineers
· Saving of time both in design and drawing
· Get quantity off take while you Design
· Unique security system and copy protection
· Flexible and convenient organization of centerlines with the option of unlimited removal and addition of roads. Every road will receive individual care, and will be drawn in a different group of layers (layout layer, CL-layer, contour lines layers, etc.).
· Arranging of the horizontal alignment in flexible and convenient method, including instant curves definitions, definition of transition curves for entrance and exit of each curve, addition of IP, removal of IP, moving of IP at any given time during any one of the design stages (even after design finish).
· Drawing the vertical alignment while setting vertical curves according to desired length/radius. Changes in the database will automatically affect the drawing. Presentation of vertical alignment for the side ditches left and right, existing and designed, both in the drawing and the data table, while maintaining the option of changing the ditches data in the section - are all made possible.
· Extract mechanism specialized for urban roads design with high frequency changing cross-sections. The mechanism will allow for definition of numerous typical sections for different road segments and their projection on the road according to width changes in the layout. Automatic reception of desired contour lines and elevations according to the definition in the typical sections.
· Broad range of possibilities for dealing with cross-sections - definition of thickness and form of roads structure including the closing method of sections edges. Definition of side ditches according to changing statuses and depths for cut and fill, automatic definition for side berms, various definitions for cover like asphalt, sidewalk, garden, retaining wall etc.
· Special mechanism for dealing with and arranging super elevations in a convenient and easy manner.
· Full interaction between layout, vertical alignment, and cross sections - any change in one will immediately cause a change in the other.
· Earthworks volumes calculations, sub-base calculations, stripping length calculations, include/exclude of stripping in the volumes calculations.
· Computations of coordinates along the centerline at station and offset for any desired distance (or distance range), coordinates computations of dibbling points in sections including safety distance.
· Regulation of under-ground drainage along roads on the designed road surface.
· Regulation of Earthworks in fields and development of the area to the side of the road.
· Immediate reception and transference of data from and to Excel (MS) program. Printing and editing of the different reports in Excel.

















4. Design

4.1 Overview of SW_ROAD Software
The SW-Road software provides complete solution to the design, drawing and quantity off-take of the road works. This is also used for producing detailed design, construction layout generation, detail drawing preparation as well as quantity estimation of all kinds of roads including complicated hill roads and the urban roads. This software has one customized Workbook in Excel for all the required data & calculations and one interactive module with easy to use menu system for drawing all Plan, Profile and Cross-sections in AutoCAD. SW_ROAD software can also be used for feasibility stage work using the topographical contour maps. The software provides complete interactive design quantities computation such that the plan, profile and cross-section can be designed and edited simultaneously. The software has been successfully adopted by many national and international organizations including private consulting firms, contractors, government organization and projects.

4.2 Survey Data Processing
The raw data that has been obtained from the Survey is collected and enter in the Excel set of the software. The software automatically gives the X, Y, Z coordinates of the spot levels .Thus, enter data gives spot levels in X, Y, Z, Remarks format which can be directly used to develop Digital Terrain Model. Further based on the remarks the features are created e.g. culverts, houses, existing road edges, existing walls etc.


4.3 Digital Terrain Modeling
SW_DTM is process for Surface Modeling which is base on the principle of Triangulated Irregular Network (TIN) from a set of points and break lines. The TIN is further used to create contours and which is further use to analysis the ground feature and drawing longitudinal profile and cross sections.
The SW_Road Software has built in Surface Modeling Module called SW_DTM. The SW_DTM is capable of processing unlimited spot levels and break lines. Break lines are defined for all the features e.g. road edges, rivers, and ridge features. The use of the break lines makes the TIN model more realistic producing longitudinal and cross-sections close to the real surface.
Using SW_DTM, We functions following parts of the roads:
Ø Drawing of the counter point and counter lines
Ø



4.4 Design Parameters:

4.4.1 Horizontal alignment

A change in the direction is required in roadway alignment due to obligatory points and topography of the terrain. Horizontal alignment is done for fixing the road direction in horizontal plane.
Deflection angle, D = 180° - interior angle

If +ve, the survey line deflects right (clockwise) with the prolongation of preceding line and deflects left if –ve (anti-clockwise). The radius was assumed according to the deflection angle. Then the tangent length, EC, BC, apex distance along with their chainage were found by using following formulae,
Tangent Length (T L) = R * tan (D/2)
Length of Curve (L.C) = 3.142 * R * D/180
Apex distance = R * 1/ (Cos (D/2)-1)
Chainage of BC = Chainage of IP – TL
Chainage of MC = Chainage of BC +LC/2
Chainage of EC = Chainage of MC + LC/2

The BC and EC points were located along the line by measuring the tangent length from the apex and the points were marked distinctly. The radius was chosen such that the tangent does not overlap. The apex was fixed at the length of apex distance from IP along the line bisecting the interior angle.

The different elements of horizontal curves were designed using equations that were already given in above. It was tried to keep large radius as far as possible the minimum radius of curve adopted is 15m. Most of the curves are having radius around 20-50m. A list of Horizontal curves and their elements are presented in the drawings and lists with its design parameters are presented in the appendices.

4.4.3 Extra-Widening

As recommended by India Road Congress and using formula given above the inner edge of carriageway has been widened on gorixontal curves to facilitate safe passing of vehicles. Due to constaints and place for drainage purpose the widening is equally recommended in both sides in some curves.

4.4.4 Vertical Alignment

The vertical alignment includes selection of gradient and design of summit and valley curves. The maximum gradient adopted is 10% which is permitted in NRS. The average gradient is 7%. For smooth changes from one gradient to another gradual vertical parabolic curves were provided.
Y=Ax
2/200L
Where,
A=Deviation of grades in percent
L=Length of curve
X=horizontal distance
The length of both summit and valley surveys are calculated as per the equation discussed above.

4.4.5Cross-Section
4.4.5.1 Cross section:

The cross-section is designed after designing Alignment and Profile. The SW-Road software has got wide range of capabilities in automated cross-section design. The provision of various kind of retaining structures and breast walls, and drainage structures along with the cut/fill slope as per design specifications are provided in software.
The road structures and drainages are the positioned as per the criteria or by trial and error method. The trial and error method is used to optimize the design. By shifting the center line and using appropriate structures, the final alignment and profile can be obtained.
The cross section design was carried out taking plan and profile under consideration. For embamkment areas the sides slopes of 1.5 H : 1 V
are adopted and sides slopes in cutting ranges from 0.5 : 1 (H:V) To 0.25 : 1 (H:V) base on soil types.

4.4.5.2 Shoulder width

Shoulder Width of 0.5 m in either side of the edge line of road has been provided.

4.4.5.3 Carriageway Width

Carriageway width is equal to 3.5 m is proposed.

4.4.5.4 Formation Width

Minimum formation width of 4.5 m is proposed which includes carriageway and its shoulder width on both sides.

4.4.5.5 Right of Way

As per N.R.S right of way equal to 15 m on either side of road is suggested.

4.4.5.6 Camber:

A 4% of camber was provided for the proposed gravel surface and 5% for shoulder surface towards hillside.

4.4.6 Drainage
4.4.6.1 Geraneral
The durability of road pavement and sub grade as a whole depends on the proper drainage management. Collection, transportation and disposal of surface water originating on or near of the right of way or , flowing in the stream crossing or, bordering that right of way , involves the need of proper drainage system in order to keep the sub grade material free from excessive moisture. Highway drainage is the process of removing and controlling excess surface and sub-soil water entering the road formation. This includes interception and diversion of water from the road surface and sub-grade. The installation of suitable surface and subsurface drainage system is an essential part of highway design and construction. Longitudinal and Cross drains are designed where safe drain of rainwater from the road surface is necessary. The longitudinal drains may be either lined or unlined which is determined according to soil condition and road slope is provided. Cross drainage structures like culvert, causeway is provided where the road has to cross natural streams or non-perennial flow of water.

In the project, most of the side drains are trapezoidal section. For the proper drainage of road and terrain, pipe and slab culvert is used at different interval according to the site condition.
Drainage system and other road structure would be needed to achieve stable road formation and to protect the execting and designed slopes from erosion. Adequate protection works (bioengineering measures) are suggested for erosion control for erosion control in side slopes of road.
4.4.6.2 Longitudinal Drainage
Providing the side drain off the surface water from the uphill side to the road and the road itself. The catch drain will be needed in the areas of heavy cutting to the gully cutting in order to better drainage. Trapezoidal side drains (as per drawing) of the design size of stone masonry are suggested. The minimum longitudinal slope of side drain is 1%. Side slopes of drain masonry proposed are vertical on the hillside and 1:2.5 on the roadside.

4.4.7 Retraining Structures:

In order to secure the hill slope and provide stability and to minimize the earthworks, the number of retaining structures are suggested. Gabion walls are provided at different chainages. The specification of gabion walls is as suggested by Design standards. These are structures used to hold back and maintain a difference in the elevation of the ground surface. The main purpose of retaining structures in road construction is to stabilize surface. In this project, typical retaining wall used in similar terrain and geological condition have been used. Individual design of the walls and checking against failure is not carried out.
4.4.7. 1 Types of retaining structures
Dry stone wall
§ Extensively constructed in green roads to minimize to depth of cutting.
§ Low cost than masonry / gabion walls.
§ Locally available manpower can be used (trained during construction).
§ Easy to construct. Longitudinal drainage is not required having gradient less than 7%(except in special case)
§ The outward slope of wall is taken 1:3(H: V) and foundation slope is taken inward 3:1(H: V).

Gabion walls
In general practice, Gabion wall are 1x1 m section. When cross slope is 45 degree or more, the gabion walls (in general) are constructed.
§ In loose soil with landslide potentiality or in swampy soil, gabion wall is used.
§ Top part of gabion wall is to be kept below the formation level of road.
Refer- Drawing No. TCS

Masonry stone wall
When the soil is loose and cutting slope is high, this type of masonry wall is used. We can use either vertical or inclined masonry walls.


The stone masonry structure are suggested as retaining as well as breast walls in difficult points where gabion and dry masonry walls are not possible to construct.








4.4 Design Criteria


The design of road depends on several design factors. The important of these factors which control the road elements are:

a) Design speed

b) Gradients

c) Super-elevation

d) Extra-widening
e) Curve radius
f) Design hourly volume and capacity
g) Environmental and other factors
h) Topography
i) Geology
j) Hydrology
k) Sociological Considerations


a) Design speed
The speed is the most important factor controlling the road design. The design speed is decided taking into account the overall requirements of the highway and also the topography. The elements of road like pavement surface characteristics, width and clearance requirements, the sight distance requirements, the horizontal alignment elements like super-elevation etc mainly depends on design speed of the road.

The overall design of geometries of any highway is the function of design speed. The design speed of roads depends upon class of road and terrain. According to the department of road, the present road falls under the Feeder Road Class A, Nepal. The design speed considered in this project is 40 Km/hr.

b) Gradients
The gradients influence the geometric design of highway significantly. The terrains are classified based on the general slope of the country across the alignment, as plain rolling, mountainous and steep terrains. The speed standards affect every geometric design element. Further in hilly terrain, it is necessary to allow for steeper gradients and sharper horizontal curves due to the construction problems. In this project, the maximum gradient we have taken is 12%
c) Super-elevation
The maximum super elevation should be within 0.07 (except in hill road not bound by snow where the maximum allowable value is 0.1, Refer-Table 6).
In the project, we calculated the respective value of super-elevation for various radii using the above formula but for the software we provide average values of super-elevation as per the below table:
Super Elevation

Radius From
Radius To
SE (%)
0
25
7.00%
25
50
6.00%
50
60
5.00%
60
100
4.00%
100
150
3.00%
150

0.00%








d) Extra-widening (EW)
The values of Extra-widening for various radii are calculated, but the average values of the extra-widening is shown in below table. In this project, full EW begins from the 1/3 part of the transition curve from BC. For radius up to 50 m, the EW is totally used inside of the road width and more than 50 m half of EW is provided either side of the road width which is also shown in below
table.
Side Extra Widening

Radius From
Radius To
Inner
Outer
10
50
100.00%
0.00%
50
10000
50.00%
50.00%
10000

50.00%
50.00%







e) Curve radius
The larger radius of the horizontal and vertical curve makes comfort in driving. Minimum radius used is 12.5 m in horizontal curve and 15 m in vertical curve as recommended by Feeder Road Standards of Nepal. In the software we used, we can change the radius as per site condition. Due to the hilly terrain, only circular curves are used.

f) Design Hourly Volume and Capacity
The traffic flow or volume keeps fluctuating with time, from a low value during off-peak hours to the highest value during the peak hour. It will be uneconomical to design the roadway facilities for the peak traffic flow or the highest hourly traffic volume. Therefore reasonable value of traffic volume is decided for the design and this is called the design hourly volume. This value is to be determined from extensive traffic volume studies. The ratio of volume to capacity affects the level of service of the road.

g) Environmental and other factors
The environmental factors such as land erosion, water management, aesthetics, landscaping, air pollution, noise pollution and other local conditions should be given due consideration in the design on road geometrics.

h) Topography
Topography of the area in consideration significantly influence the geometric design of highways taken as classified according to the cross slope of the country as plain, rolling, hilly or mountainous and steep. As per NRS, the classification of the road is as follows:
Class
Terrain Type
Percentage Slope
1
Plain
0 to 10
2
Rolling
10 to 25
3
Hilly or Mountainous
25 to 60
4
Steep
>60

i) Geology
The major geological problem is the stability of a road edge. The road edge at most of the place is not stable so that retaining wall like gabion wall, dry stone, masonry wall and other structure are provided. The proposed road is in hilly region, so most of the cutting and filling are in normal cutting and filling.



j) Hydrology

k) Sociological Considerations


4.5 Quantity Estimation
Quantities are computed from the cross-sections at 10 m interval and averages. Further the quantities for earthworks, walls, drain are computed separately. (Ref. Table 14 and 15)

4.6 Preparation of Construction Drawings
Detailed Engineering Drawings are produced which includes plan and profile, cross-section and typical structures used. The SW_Road provide automated detailed drawings production capability in AutoCAD format. All these drawings are plotted using A3 size plotter.

The drawing can be obtained in the required scale by the command available in draw tool. As per our requirement we plotted plan in 1:5000 scale and printed in 1:2. Similarly, we plotted profile with horizontal scale in 1:1000 and vertical scale in 1:100 and printed in 1:2 and lastly cross- section was plotted in 1:100 and printed in 1:1





5.0 LIMITATIONS AND CONSTRAINTS

Ø Because of time constraints and the site being so far, the survey data was provided by the consultant.

Ø All the design was done by the use of software, and all drawings & quantities are also extracted with the help of the software. The comparison with manual designing could not be done as it was not performed.

Ø Detail cross-sections are designed at every 10 m interval but only 100 m interval cross-sections are included in the report to reduce the volume of the report.

Ø No structure design analysis was performed, hence all the retaining structures are provided as per typical sample of similar type of projects launched in Nepal.


6.0 CONCLUSION

One of the most important infrastructures of the country Nepal is Road which is the approaching means of transportation and communication in the remote area. The dream of the development of the nation will start only by constructing the road.

Most of the Rural Roads are constructed without consideration of proper design and layout which result in temporary existence of the road. So, planning and designing are most essential for proper layout of the road. With the help of computer aided design, the tedious work of road design and layout is enhanced in a faster pace and optimization through various iterative procedures can also be easily achieved.

We have successfully completed our project as per assigned in the specified period. We have tried to incorporate all the essentials as far as possible. All the drawings and design calculations, relevant curve data and reduced levels of each base point (IP’S), cost estimate and rate analysis, cross drainage structures, pipe culverts and so on have been included in the report.

We became familiar with the software SW-DTM 2005 and SW-ROAD 2005 which we have used in our project assignment and hope that it will be very much useful to us in the coming days of our profession.