High Way Project 2010 (Summer Group 1)

HIGHWAY ENGINEERING FINAL YEAR PROJECT ZIWAY-BUTAJIRA ROAD

CHAPTER ONE INTRODUCTIONTransportation plays an enormous role in our everyday lives. Each of us travels somewhere almost every day, whether it be to get to work or school, to go shopping, or for entertainment purposes. In addition, almost everything we consume or use has been transported at some point. There are so many ways of transportation, but in this document we concern on road transportation. Highways are the important part of our life, the economy of the society as well as it is Part of the infrastructure. Also it is important for the change location of humans, goods and information. The better of this structure is the faster, more effective and cheaper, can be the capacities of the society used. Traffic security efficiency, economy, environmental protections are some points which considered during design of highway. The development of road transportation plays a great role in a countrys economic development .Roads are the basic infrastructure in which its service extends facilitating the growth and keeping the different sectors of the economy functional. A country should have adequately designed enough number of roads connecting its main parts. This helps the sufficient mobility of products, raw materials and labor as well as it has a far reaching effects embracing administration convenience and creating national integration and cohesion, which enhance for a better economic achievement of the country, it is this and unmentioned needs which motivate us to do our final year project on High way.BY GROUP 1 Page 1


This project deals with the design of three kilometer of Ziway-Butajiraroad. The ZiwayButajira road is found in the southern part of the country starts at ziway, which is 160km from Addis Abeba on route and turn to west at Ziway. The total length of our project is about 3000m or 3km. The design of this road comprises geometric design like Horizontal and vertical alignment, Earth work, drainage design, and pavement design of the road to a design standard DS 4. The project design is done using all important standards and followed the manuals especially ERA manuals and speculator consideration is made and each necessary steps is followed to make our project the best of all.

CHAPTER TWO PROJECT LOCATION 2:1 GeneralThe ZiwayButajira road is found in the southern part of the country starts at ziway, which is 160km from Addis Abeba on route and turn to west at Ziway.

2:2 General Description of the site 2:2:1 ClimateThe area of road exhibits a dry climatic condition with the exception around Butajira which is influenced by the wet climate of the mountains area west of the town. According to climatological classification of Ethiopia it can be classified as WEINA DEGA. The climate varies from hot & semi-arid in Ziway to warm temperate in Butajira. Annual rainfall varies from 800 -1200mm. The daily minimum, mean and maximum temperature recorded of the project area is 16, 22, and 270 C, respectively. Annual variation is low and daily variation is high.

2.2.2 TopographyThe project area is sited in the main Ethiopian Rift Valley physiographic division.

2.3 GeologyBY GROUP 1 Page 2


The geological unit along the project route corridor is alluvial and lacustrine (lake) deposit such as sand, silt, clay, diatomite, limestone, and beach sand.

2.4 EconomyThe major economic activity of the population along the road corridor and its influence area is agriculture. The area is intensively cultivated for crop production. Finally the road plays a great role in the development of the area and ultimately the development of the country as a whole.

CHAPTER THREETRAFFIC SURVEY AND ANALYSIS 3.1 GENERALTraffic is the most important factor in pavement, design and stress analysis. Traffic constitutes the load imparted on the pavement causing the stresses, strains and deflections in the pavement layers and sub-grades. Hence the pavement design must account for the amount of traffic load expected over its design life. The traffic loads on pavement can be characterized by magnitude of load (wheel load or axle load) consideration of load (axle and wheel configuration single dual wheel, single /tandem/ tire axle, wheel and axle spacing), load repetitions and other considerations include tire pressure, contact area vehicle speed, traffic distribution across the pavement etc. The traffic analysis is carried out to determine the pavement component required to resist the traffic load during the design period. The structural parameters required to determine the traffic load are 1 Select design periodBY GROUP 1 Page 3


2 Estimate initial traffic volume (initial AADT) per class of vehicle. 3 Estimate traffic growth . 4 Determine cumulative traffic volume over the design period. 5 Obtain mean equivalent load. 6 Estimate cumulative ESA over the design period (in one direction). 7 Select appropriate traffic class (based on ESA ) for flexible pavement design.

3.2 TRAFFIC SURVEYS3.2.1 SPEED SURVEYSSpeed surveys are usually undertaken mid-block, such as to obtain the maximum speed profile, location does sometime vary or become close to an intersection if there is a unique data need often associated with a road safety issue. Collection techniques can include:y y

Radar Speed gun Data Logger with typically pneumatic road tube or some other axle sensor, this being the most cost effective method for most long and short term data requirements. Recorder Time of vehicles between 2 known points, eg record registration plate and time. Video camera and manual or screen analysis via pixilation variation technique.

y y

GPS can also be a useful device for analysis of speed profiles for certain known vehicles say a bus, plus the provision of other route based information and travel times.

BY GROUP 1

Page 4


Different types of speed measurements are used in traffic engineering: Spot speed is the instantaneous speed of a vehicle at a specified location. Running speed is the average speed maintained by a vehicle over a given course while the vehicle is in motion. It is significant to note the clause while the vehicle is in motion, because the running speed is obtained by dividing the length of the course by the time the vehicle is in motion, i.e. by the running time, which excludes that part of the journey time when the vehicle suffers delay. Thus,

Running speed !

length of course length of course ! journey time - delay running time

Journey speed, also known as overall travel speed, is the effective speed of a vehicle between two points, and is the distance between two points divided by the total time taken by the vehicle to complete the journey, including all delays incurred en-route.

Thus:

Journey speed !

Distacne Total journey time (including delays)

Time mean speed is the average of the speed measurements at one point in space over a period of the time. It is the average of the number of spot speed measurements. Space-mean speed is the average of the speed measurements at an instant of time over a space. Use of Speed, Journey Time and Delay Studies (a) Spot speeds i. For geometric design of roads. Based on the speed studies, the design speed can be selected for design of horizontal curves, vertical curves, and super-elevation. ii. For regulation and control of traffic operations. They enable the safe speed limit to be established and speed zoning to be determined. BY GROUP 1 Page 5


iii. iv. v. vi.

For traffic signal designs. For analyzing causes of accidents. For before and after studies of road improvement. To solve the problems of congestion.

(b) Journey speeds and delays i. ii. The cost of a journey depends upon the speed at which it is made. Journey-time studies on a road network in a town are useful to evaluate congestion, capacity, level of service iii. In transportation planning studies, the determination of the travel time is necessary for carrying out the trip assignment. Also travel time and delays are some of the factors affecting modal choice. iv. v. To assess the effectiveness of improvement measures by comparing before and after studies. Delay studies at intersections provide data for the design and installation of the appropriate traffic control device. Site selection for survey: 1. The location at which measurements are taken is governed by the specific purpose for which the data are required. For example if the data are likely be used to analyze the accident pattern, the survey will be done at high accident frequency locations. 2. Generally straight, level, and open sections of highways should be selected so as to minimize the influence of geometric features of the highways, road-side development and intersections.

Table 3.1: Recommended Base Lengths for Spot Speed SurveyAverage speed of traffic stream (kmph) Less than 40 40 to 60 Greater than 65 Base length (m) 27 54 81

3.2.2 Methods of Measurement for Spot Speeds

BY GROUP 1

Page 6


The methods available for measuring spot speeds can be grouped as under: a) Those that require observation of the time taken by a vehicle to cover a known distance b) Radar speed meters which automatically record the instantaneous speed c) Photographic method The location at which measurements are taken is governed by the specific purpose for which the data are required. For example if the data are likely be used to analyze the accident pattern, the survey will be done at high accident frequency locations. Generally straight, level, and open sections of highways should be selected so as to minimize the influence of geometric features of the highways, road-side development and intersections.

3.3 DESIGN PERIODThe length or duration of time during which the pavement structure is expected to function satisfactorily without the need for major intervention (rehabilitation such as overlays or reconstruction) or the duration on time until the pavement structure reaches its terminal condition (failure condition). Selecting appropriate design period depends on Functional importance of the road. Traffic volume. Location & terrain of the project. Financial constraints.

BY GROUP 1

Page 7


Difficulty in forecasting traffic 3.4 INITIAL TRAFFIC VOLUME (AADT)1. VEHICLE CLASSIFICATION y y y y Small axle loads from private cars and other light vehicles do not cause significant pavement damage. Damage caused by heavier vehicles (commercial vehicles). Hence, important to distinguish the proportion of vehicles which cause pavement damage from total traffic. To do this, we need to have a vehicle classification system: To distinguish between commercial vehicles and small cars Distinguish between the different types of commercial vehicles and group them according to their type, size (loading), configuration, etc. 2. TRAFFIC COUNT

Traffic count necessity: To assess the traffic carrying capacity of different types of roads. Examine the distribution of traffic between the available traffic lanes. In the preparation of maintenance schedules for in- service roads. In the forecasting of expected traffic on a proposed new road from traffic studies on the surrounding road system

Traffic volume data determined from: Historical traffic data available in relevant authorities (ERA, 3 times a year) and/ or By conducting classified traffic counts On the road to be designed- if the road is an existing road On other parallel routes and /or adjacent roads for new roads

Traffic volume data may vary daily, weekly and seasonally BY GROUP 1 Page 8


Hence to avoid error in traffic analysis and capture the average yearly trend,

minimum seven days count recommended ERA recommended procedure conduct seven days classified traffic count 5 days for 16 hrs Minimum 2 days for 24 hrs

3. ADT (Average daily traffic) ADT is determined from the traffic count data as follows: Adjust the 16 hrs traffic count data in to 24 hrs data by multiplying with the average night adjustment factor Night adjustment factor= (24 hrs traffic)/16 hrs traffic:- obtained from the two days 24 hrs count data.

(ADT)o = the current average daily traffic =average of the seven days 24 hrs traffic volume data. 4. (AADT)o (Annual average daily traffic =total annual traffic in both directions divide by 365 )

3.5 TRAFFIC GROWTH RATE (TRAFFIC FORECAST) Very uncertain process Requires making analysis and forecast of past and future traffic growth trends, social and economic development trends, etc. In forecasting, traffic characterized in to the following: NORMAL TRAFFIC: Traffic that would pass along the existing road or track even if no new or improved pavement provided. DIVERTED TRAFFIC: Traffic that changes from another route to the project road because of the improved pavement, but still travels between the same origin and destination. GENERATED TRAFFIC:

BY GROUP 1

Page 9


Additional traffic which occurs in response to the improvement of the road It may arise either because a journey becomes more attractive by virtue of a cost or time reduction or because of the improved development that is brought about by the road investment.

3.5 AXLE LOAD SURVEY Carried out together with the traffic count Each axle of the vehicles is weighed and EALF computed for each axle EALF=4.5

where; EALF= equivalent axle load factor Lx= load of each axle in KN.

TRACK FACTOR o Track factor can be computed for each vehicle by summing up the number of ESAL per vehicle o Average track factor can be computed for each vehicle category by summing up EASL of all the vehicles in each category and dividing buy the number of vehicles (of that category) weighed

=

where;

= track factor for the ith vehicle categoryN= number of vehicles weighed (of the ith vehicle category) during the axle load survey. ESALj = number of equivalent axle load for the jth vehicle.

3.6 DESIGN TRAFFIC LOADING The data and parameters obtained from the studies discussed in the preceding sections can now be used to estimate the design cumulative design traffic volume and loading. I. follows; Adjust for lane and directional distribution of traffic-the AADT should be adjusted as

BY GROUP 1

Page 10


Lane distribution factor (p); accounts for the proportion of commercial vehicles in the design lane. For two lane highways, the lane in each direction is the design lane, so the lane distribution factor is 100%. Directional distribution factor (d); factor that accounts for any directional variation in total traffic volume or loading pattern. It is usually 0.5(50%). II. Calculating (AADT)1 (AADT)1= annual average daily traffic (both directions) at year of road opening (year at which construction works are completed and the whole road is made open for traffic) If time between traffic count year (design time) and estimated year of road opening =x, then (AADT)1= (AADT)o (1+r)x III.

Cumulative traffic volume (T)- can be computed for all traffic (T) or each vehicle class (Ti) 365(p) (D) (AADT)1

Where;

cumulative volume of traffic for the ith commercial vehicle class in the design lane

over the design period (adjusted for lane distribution and direction)Annual growth rate for the ith commercial vehicle class

Lane distribution factor Directional distribution factor

IV.

Design traffic (cumulative equivalent standard axle load-CESAL)- is computed by

multiplying a total traffic volume for each vehicle (Ti) by its corresponding track factor (TFi) Design traffic load =CESAL= V. The CESAL is used to determined the traffic class to be employed for pavement design Page 11

BY GROUP 1


A further factor influencing the development of road design standards, and in particular the design speed, is the volume and composition of traffic. The design of a road should be based in part on factual traffic volumes. Traffic indicates the need for improvement and directly affects features of design such as widths, alignments, and gradients. Traffic data for a road or section of road, including traffic trends, is generally available in terms of annual average daily traffic (AADT). Using road functional classification selection and design traffic flow, a design class, or standard, is selected from Table 3-1, with reference to the design parameters associated with that class. The functional hierarchy is such that traffic aggregates as it moves from feeder to main collector to link the trunk roads. However the actual flows will vary from region to region and it is important that the designation of a road by functional type should not give rise to over-design for the traffic levels actually encountered. Design classes DS1 to DS10 have associated bands of traffic flow as was shown in Table 31. The range of flows extends from less than 20 to 15,000 motorized vehicles per day (excluding motorcycles), and covers the design conditions for all single and dual carriageway roads. Although the levels of flow at which design standards change are based on the best current evidence, the somewhat subjective boundaries should be treated as approximate in the light of uncertainties inherent in traffic estimation and future forecasting. Therefore, the Design Traffic Flow shall normally be limited to be no more than one Design Class step higher than the average daily traffic (AADT) in the first year of opening. For example, a road with a first year traffic flow of 190 vehicles per day rising to 1,100 vehicles per day in the last year of its design life, should be constructed to Design Class DS4 rather than Design Class DS3 (see Table 3.1)

BY GROUP 1

Page 12


The design traffic flow band in this case is therefore 200 1000 vehicles per day (DS4) Design to the higher Design Class DS3 would result in an over-design of the road during almost the whole of the life of the road and may provide a solution that was less than economic.Table 3-1: Design Standards vs. Road Classification and AADT Road Functional Classification Design Standard No. Design Traffic Flow (AADT) 10,000 15,000 5,000 10,000 1,000 5,000 200 1,000 100 200 50 100 30 75 25 50 0 25 0 15

DS1 T R L M A C O F E E D E R L L E C T O R A C C E S S DS10 DS8 DS9 I N DS6 DS7 I N K U N K DS4 DS5 DS2 DS3

It may be desirable, especially for primary roads, to develop geometric standards that are consistent despite variations in traffic volumes. Conversely, a policy dependent on AADTBY GROUP 1 Page 13


would result in a more economical allocation or resources. This dichotomy requires a special attention of the engineer in choosing the geometric design parameters. Table 3-1 repeats the overlaps that may exist between road functional classifications and AADTs.

The given data:Traffic data & growth rate The AADT for period 1999-2003 is given below and the growth rate is assumed to be 5%. Moreover, the directional split is assumed to be 50% and the opening of the road to traffic is assumed to be in the year 2006 GC. Table3-2 AADT for the period of 1999-2003 Year 1999 2000 2001 2002 2003 Cars 117 90 96 88 148 Bus 111 99 100 94 105 Vehicle AADT0 type Cars 148 Bus 105 Medium 79 truck Heavy truck 67 Articulated 8 truck Total 407 Medium Truck 87 67 77 58 79 Heavy Truck 47 37 32 28 67 AADT1=AADT0(1+r)x 163 116 87 74 9 449 Articulated Truck 18 13 6 12 8 Total 380 306 311 280 407

Table3-3 TOTAL AADT

Where: - AADTo =average annual daily traffic at 2003 (given) AADT1= is defined as the total annual traffic summed for both directions andBY GROUP 1 Page 14


Divided by 365. . r = average growth rate of traffic% (5% given) x= the anticipated number of years between the traffic survey and the opening of the road.(2years given) This indicates that the design standard of the road is DS4 which is taken from table 3.1.

3.7Road Functional Classification and NumberingThe functional classification in Ethiopia includes five functional classes.The following are the functional classes with their description.

I.

Trunk Roads (Class I)

Centers of international importance and roads terminating at international boundaries are linked with Addis Ababa by trunk roads (see Table A-1). They are numbered with an "A" prefix: an example is the Addis-Gondar Road (A3). Trunk roads have a present AADT u1000, although they can have volumes as low as 100 AADT (see Table 2-1). II. Link Roads (Class II)

Centers of national or international importance, such as principal towns and urban centers, must be linked between each other by link roads (see Table A-2). A typical link road has over 400 - 1000 first year AADT, although values can range between 50-10,000 AADT. They are numbered with a "B" prefix. An example of a typical link road is the Woldiya- Debre Tabor- Woreta Road (B22), which links, for instance, Woldiya on Road A2 with Bahir Dar of Road A3.

III. Main Access Roads (Class III) Centers of provincial importance must be linked between each other by main access roads (see Table A-3). First year AADTs are between 30-1,000.IV. Collector Roads (Class IV)Roads linking locally important centers to each other, to a more important center, or to higher class roads must be linked by a collector road. First year AADTs are between 25-400. BY GROUP 1 Page 15


V.

Feeder Roads (Class V)Any road link to a minor center such as market and

local locations is served by a feeder road. First year AADTs are between 0100. Table3-4 ERA design period for different standard roads Road classification Design period (years) Trunk road 20 Link road 20 Access road 15 Other roads 10

Roads of the highest classes, trunk and link roads have, as their major function to provide mobility, while the primary function of lower class roads is to provide access. The roads of intermediate classes have, for all practical purposes, to provide both mobility and access. In the case of our project data (Ziway to Butajira ) which have AADT1=449 and the road have the center of provincial importance, this two factors lead to be classified to main access road.

3.8Geometric Design Standards for Low Volume RoadsThe geometric standards for low volume roads have less importance than whether a road exists and whether it is possible at all times. In such circumstances, it is appropriate to adopt inexpensive standards that enable the further development of a system of such feeder roads at minimal cost. This policy encourages overall national economic development. Design Speed The Design Speed is used as an index which links road function, traffic flow and terrain to the design parameters of sight distance and curvature to ensure that a driver is presented with a reasonably consistent speed environment. In practice, most roads will only be constrained to minimum parameter values over short sections or on specific geometric elements.BY GROUP 1 Page 16


Design elements such as lane and shoulder widths, horizontal radius, superelevation, sight distance and gradient are directly related to, and vary, with design speed. Thus all of the geometric design parameters of a road are directly related to the selected design speed. The design speeds given in Table 2-1 have been determined in accordance with the following guidelines:(i) (ii) (iii) Drivers on long-distance journeys are apt to travel at higher speeds than local traffic. On local roads whose major function is to provide access, high speeds are undesirable. Drivers usually adjust their speeds to physical limitations and prevailing traffic conditions.

Where a difficult location is obvious to the driver, he is more apt to accept a lower speed of operation.

(iv) Economic considerations (road user savings vs. construction costs) may justify a higher design speed for a road carrying large volumes of traffic than for a less heavily trafficked road in similar topography. (v) Change in design speed, if required due to a change in terrain class, should not be effected abruptly, but over sufficient distances to enable drivers to change speed gradually. The change in design speed should not be greater than one design speed step, and the section with the lower geometric standards should be long enough to be clearly recognizable by drivers (not, for example, just one single curve). (vi) It is often the case that the physical terrain changes two steps, i.e.- from mountainous to flat terrain. Where possible in such circumstances, a transition section of road shall be provided with limiting parameters equivalent to the rolling terrain type. Where this is not possible, i.e.- a Departure from Standards,special attention shall be given to the application of warning signs and/or rumble strips the driver to the changing conditions. It is important to note that the design of a road in accordance with a chosen design speed should ensure a safe design. The various design elements have to be combined in a balanced way, BY GROUP 1 Page 17 to alert


avoidingthe application of minimum values for one or a few of the elements at a particular location when the other elements are considerably above the minimum requirements.

CHAPTER FOUR GEOMETRIC DESIGN4.1 HIGHWAY ALIGNMENT AND ROUTE LOCATIONIn general the aim of a highway selection process is to find a location for the new road that will result in the lowest total construction, level, traffic and environmental costs. Before an attempt can be made at selecting a physical location for a highway design, data must be available regarding traffic desires and the planning intentions with in the area to be transversed.

4.1.1 STEPS IN ROUTE LOCATION / SELECTION1. Know the termini points of the scheme. 2. From the study of map of the area, identify and locate Parks Any ancient relics Existence of monasteries Mining sites Existing transport facilities Location of construction materials 3. Conduct preliminary and reconnaissance surveys and collect information on predetermined area i.e detail of topography, climate, soil, and vegetation and any other factors, (i.e geology, flood, land slide etc). 4. Based on the information collected in the previous two steps select a corridor 5. Identify a number of possible center lines within the corridor. 6. Make a preliminary design for the possible alternatives and plot on the areas map. 7. Examine each of the alternative alignment with respect to grades, volume of earth work, drainage, erasing structures, etc to select best alternative route. BY GROUP 1 Page 18


8. Make final design and location of the selected alternative route.

So, for our project having this in our mind and based on the given data and information, we have been selected the following route.

4.2 TerrainThe geometric design elements of a road depend on the transverse terrain through which the road passes. Transverse terrain properties are categorized into four classes as follows: Flat or gently rolling country, which offers few obstacles to the construction of a road, having continuously unrestricted horizontal and vertical alignment (transverse terrain slope up to 5 percent). ROLLING: Rolling, hilly or foothill country where the slopes generally rise and fall moderately and where occasional steep slopes are encountered, resulting in some restrictions in alignment (transverse terrain slope from 5 percent to 25 percent). MOUNTAINOUS: Rugged, hilly and mountainous country and river gorges. This class of terrain imposes definite restrictions on the standard of alignment obtainable and often involves long steep grades and limited sight distance (transverse terrain slope from 25percent to 50 percent). ESCARPMENT: In addition to the terrain classes given above, a fourth class is added to cater to those situations whereby the standards associated with each of the above terrain types cannot be met. We refer to escarpment situations inclusive of switchback roadway sections, or side hill transverse sections where earthwork quantities are considerable, with transverse terrain slope in excess of 50 percent). In general, construction costs will be greater as the terrain becomes more difficult and higher standards will become less justifiable or achievable in such situations than for roads in either flat or rolling terrain. Drivers accept lower standards in such conditions and therefore adjust their driving accordingly, so minimizing accident risk. Design speed willBY GROUP 1 Page 19


therefore vary with transverse terrain. It is often the case in Ethiopia that the roadway can be designed to a higher speed than is indicated by the transverse terrain type. For instance, an alignment could be chosen through rolling terrain that gives essentially a flat highway configuration. Similarly, a narrow plateau should be chosen for an alignment in otherwise mountainous terrain. The discrepancy arises from an ability to choose a roadway longitudinal slope significantly superior to the transverse slope. Under such circumstances, the Engineer should use his judgment in assigning a higher design speed to the roadway segment. Departures from StandardsIt is anticipated that there may be situations where the designer will be compelled to deviate from these standards. An example of a Departure from Standard is the inclusion of a switchback or the use of a gradient greater than the desirable value. Where the designer departs from a standard, he must obtain written approval from ERA. The Designer shall submit the following information to ERA:

The number, name, and description of the road The facet of design for which a Departure from Standards is desired; A description of the standard, including normal value, and the value of the Departure from Standards The reason for the Departure from Standards, and Any mitigation to be applied in the interests of safety.

The Designer must submit all major and minor Departures from Standards to the Design and Research Division Manager for evaluation. If the proposed Departures from Standards are acceptable, the Departures from Standards will be submitted to the General Manager for final approval.

BY GROUP 1

Page 20


Table 4-2:

Geometric Design Parameters for Design Standard DS4 (Paved) from ERAUnit km/h M M % M Flat 85 155 340 25 270 Yes % % % % K K % % M 4 6 0.5 8 60 36 2.5 4 50 Rolling 70 110 275 25 175 Yes 5 7 0.5 8 31 25 2.5 4 50 Mountainous 60 85 225 15 125 No 7 9 0.5 8 18 18 2.5 4 50 Escarpment 50 55 175 0 85 No 7 9 0.5 8 10 12 2.5 4 50 Urban/PeriUrban 50 55 175 20 85 No 7 9 0.5 4 10 12 2.5 4 50

Design Element Design Speed Min. Stopping Sight Distance Min. Passing Sight Distance % Passing Opportunity Min. Horizontal Curve Radius Transition Curves Required Max. Gradient (desirable) Max. Gradient (absolute) Minimum Gradient Maximum Super elevation Crest Vertical Curve Sag Vertical Curve Normal Cross fall Shoulder Cross fall Right of Way

BY GROUP 1

Page 21


The following photos will illustrate different types of TerrainsFlat Terrain; Flat Roadway Alignment

Rolling Terrain; Flat Roadway Alignment

BY GROUP 1

Page 22


Mountainous Terrain; Flat Roadway

BY GROUP 1

Page 23


In this project the nature of terrain is mainly flat and rolling. It is shown as in the following table.

Table 4-3 Transverse cross section slope checking dataStation 0+020 0+100 0+200 0+300 0+400 0+500 0+600 0+700 0+800 0+900 1+000 1+100 1+200 1+300 1+400 1+500 1+600 1+700 1+800 Change in vertical 3.6 1.8 0.1 0.1 1.7 14.2 15.9 4.4 0.9 1.0 3.3 4.8 7.3 8.5 7.3 2.5 6.3 8.3 4.5 Change in horizontal 50.5 69.4 71.5 61.9 73.6 73.6 73.4 73.6 73.6 73.6 73.6 73.6 73.6 73.6 73.6 68.8 73.6 73.6 73.6 Slope (%) 7.13 2.59 0.14 0.16 2.31 19.29 21.66 5.98 1.22 1.36 4.48 6.5 9.0 11.50 9.90 3.60 8.60 11.30 6.10 Remark Rolling Flat Rolling Flat Rolling Flat Rolling

BY GROUP 1

Page 24


1+900 2+000 2+100 2+200 2+300 2+400 2+500 2+600 2+700 2+800 2+900 3+000

1.0 2.1 2.4 3.5 3.2 2.0 2.7 11.2 2.9 2.5 1.5 0.1

73.6 73.6 73.6 73.6 65.8 73.6 73.6 69.8 73.6 73.6 73.6 73.6

1.36 2.90 3.30 4.80 4.90 2.70 3.70 16.00 3.90 3.40 2.00 0.10

Flat Rollin g Flat

BY GROUP 1

Page 25


Table4-4 Design Standards vs. Road Classification and AADT

Road Functional Classification

Design Standa rd

Design Traffic Flow (AADT)*

Surface Type

Width (m)

Design Speed (km/hr)

Urban/sem i-Urban

Carriage way DS1 T R U L N I M N A C O F E E D E R L E C T O R S A C C E S S DS10 015 Unpaved 3.3 DS8 2550 Unpaved 4.0 K I N DS6 50100 Unpaved 6.0 DS5 100 200 Unpaved 7.0 K DS4 2001000 Paved 6.7 DS3 10005000 Paved 7.0 DS2 500010000 Paved 7.3 10000**15000 Paved***

Shoulder

Flat

Rolli Mountai ng nous 100 85

Escarp ment 70 50

Dual 2 See T.2-2 x 7.3

120

See T.2-2

120

100

85

70

50

See T.2-2

100

85

70

60

50

See T.2-2

85

70

60

50

50

See T.2 -2

70

60

50

40

50

See T.2-2

60

50

40

30

50

DS7

3075

Unpaved

4.0

See T.2-2

60

50

40

30

50

See T.2-2

60

50

40

30

50

DS9

025

Unpaved

4.0

See T.2-2

60

40

30

20

40

See T.2-2

60

40

30

20

40

BY GROUP 1

Page 26


As it was identified in chapter three the road design Standard is DS4. And the terrain type is flat and rolling which is shown on table 4-3 above. According to this, all the parameters used for this type of road is compiled bellow which is based on ERA design manual.Table 4-5: Design Parameters for Design Standard DS4 (Paved) road of selected terrain Design Element Design Speed Min. Stopping Sight Distance Min. Passing Sight Distance % Passing Opportunity Min. Horizontal Curve Radius Transition Curves Required Max. Gradient (desirable) Max. Gradient (absolute) Minimum Gradient Maximum Super elevation Crest Vertical Curve Sag Vertical Curve Normal Cross fall Shoulder Cross fall Right of Way Carriage way % % % % k k % % m m Unit km/h m m % m Flat 85 155 340 25 270 Yes 4 6 0.5 8 60 36 2.5 4 50 6.7 Rolling 70 110 275 25 175 Yes 5 7 0.5 8 31 25 2.5 4 50 6.7

BY GROUP 1

Page 27


4 .3 HORIZONTAL ALIGNMENT 4.3.1 GENERAL NOTES ON HORIZONTAL ALIGNMENTThe design element of the horizontal alignment is the tangent or straight section, circular curve, the transition curve spiral and the super elevation section. These elements and sight distances are presented in detail as follows. The horizontal alignment of a road must be carefully chosen in order:-- To provide good drainage -- To avoid soft or swampy areas. -- To minimize earthworks -To avoid shortage of construction materials

-- To break monotony and avoid glare from head light anda setting sun ,the maximum length of tangents should not exceed 4000m.If necessary a 4 degree curve should be introduced (left and right).Avoid short or sharp curves at end of long straights ;or short length of straights between two curves should be 100m. Replace compound curves by a single curve. Avoid the combination of vertical and horizontal curves; if not the vertical curves should be wholly within the horizontal curve. A horizontal circular curve is a curve in plane to provide change in direction to the center line of the road and there are different types of curves such as:-Simple horizontal curves -Compound horizontal curves -Reverse horizontal curves The requirement of good horizontal curve is -Sufficient stopping sight distance -Sufficient passing sight distance -Smooth turning possibility and as much as possible approximate large radius.

BY GROUP 1

Page 28


4.3.2 Tangent SectionsFrom an aesthetic point of view, tangent sections may often be beneficial in flat country but are less so in rolling or mountainous terrain. From a safety standpoint, they provide better visibility and more passing opportunities. However, long tangent sections increase the danger from headlight glare and usually lead to excessive speeding.

4.3.3 Horizontal Circular CurveWhen a vehicle moves in a circular path, it is forced radially outward by centrifugal force. The centrifugal force is counterbalanced by super elevation of the roadway land/or the side friction developed between the tires and the road surface. For calculation of the minimum horizontal radius, R min, for a particular design speed, the following equation shall be used: Rmin=VD2/127(e+f) Where VD = Design Speed (km/h) e = Maximum super elevation (%/100) f = Side friction coefficient (given in Tables) In our case the radius of all the curves are already specified in alignment . so here the speed of curve should be under the ERA recommended For curve 1 VD = R * 127 (e + f) = 80 * 127 (0.08 + 0.42) = 70 But ERA recommended R min = 175 for speed of 70 km/ hr therefore the speed for the specified radiuses are adjusted according to ERA manual

BY GROUP 1

Page 29


Table4-4 Minimum Radii of Horizontal curves 8% Super elevation 20 30 40 50 60 70 85 100 Design speed V(km/hr) 15 30 50 85 125 175 270 395 Min. Horizontal Radius R(m) 0.18 0.17 0.17 0.16 0.15 0.14 0.14 0.12 Side Friction factor(f) Table 4.5 Radius of curves and its corresponding speed and side friction Curves Design speed V(km/hr) Min.Hori Radius R(m) Side Friction factor(f) 1 45 80 2 30 32 3 45 80 4 50 100 5 55 120 6 60 140 7 55 120 8 35 40 9 50 100 10 40 50

120

630

0.10

11 70 300

0.165 0.170 0.165 0.160 0.155 0.150 0.155 0.170 0.160 0.170 0.140

ELEMENT OF HORIZONTAL CURVE1.: Deflection angle by arc definition (in degrees) 2. R: Radius of curve by arc definition ECC 3.T: Tangent distance T=Rtan/2 4.E: External distance= R (sec/2-1) 5.L: Curve Length L=*2R/360 6. M: Middle Ordinate M=R (1-cos/2) 7.C: Chord from P.C to P.T = 2Rsin/2

8.Point of Curvature (P.C) = P.I-T 9.Point of Tangency (P.T) =P.C+LCBY GROUP 1 Page 30


Table 4-6 Point of intersection (PI) for our Center line . NO. 1 2 3 4 5 6 7 8 9 10 11 Station 0+435.696 0+503.110 0+705.640 0+841.263 0+983.772 1+412.875 1+757.672 1+833.301 1+946.153 2+244.063 2+694.664 North 415846.712 415844.503 416015.124 416062.992 416188.098 416570.009 416820.731 416841.687 416962.887 417175.790 417015.144 East 893031.347 893107.128 893222.287 893348.064 893422.161 893461.389 893646.503 893721.663 893726.829 893940.781 894345.941

BY GROUP 1

Page 31


Table4-7 Stations of curvesCur ve No. 1 2 3 4 5 6 7 8 9 10 11WhereBC- The station at which beginning of curve PI-The station of point of intersection EC-The station at which curve ends

BC 0+400.26 0+482.83 0+684.87 0+821.20 0+948.02 1+402.77 1+741.36 1+803.27 1+921.93 2+222.67 2+666.65

PI 0+435.70 0+503.11 0+705.64 0+841.26 0+983.77 1+412.87 1+757.67 1+833.30 1+946.15 2+244.06 2+694.66

EC 0+482.73 0+528.14 0+743.90 0+888.44 1+017.51 1+471.26 1+793.39 1+868.52 1+996.45 2+278.46 2+771.49

BY GROUP 1

Page 32


Sample calculation of horizontal curveRadius=80m, deflection angle=44.4429, /2=22.22 Tangent (T) =R tan/2 =80xtan22.22 =32.68m External distance (E) = R (sec/2-1) =80(sec22.22-1) =6.42m Middle Ordinate M=R (1-cos/2) =80(1-cos22.22) =5.94m Curve Length L=x2R/360 =44.4429 x2x80x3.14/360 =62.02m Chord from P.C to P.T =2x80sin22.22 =60.5m Point of Curvature (P.C) station =PI-T =0+435.7m-32.68m =0+403.02m Point of Tangency (P.T) station =P.C+LC =0+403.02 m+62.02m =0+465.04mBY GROUP 1 Page 33

Curve 1

=2Rsin/2


Curve No 1 2 3 4 5 6 7 8 9 10 11

Table4-8 Element of curve Radius Deflection Length Tangent Design of curve angle of curve length speed (m) ( ) (m) Circular (km/hr) (m) 80 44.4429 62.47 32.93 45 32 80 100 120 140 120 40 100 50 300 45.1941 12.1646 21.2018 33.1047 7.3401 24.5035 50.2940 25.3041 41.0049 10.2825 25.32 17.14 37.24 69.49 18.49 52.03 35.25 44.52 35.79 54.84 13.36 8.60 18.84 35.75 9.26 26.43 18.86 22.64 18.70 27.50 30 45 50 55 60 55 35 50 40 70

M

E

6.02 2.47 0.46 1.73 5.00 0.31 2.81 3.82 2.47 3.17 1.25

6.51 2.68 0.46 1.76 5.21 0.31 2.88 4.22 2.53 3.38 1.25

Note: The design speed is tabulated from table4-4 by direct substitution or interpolation of the provided radius and by comparing and limiting with the terrain type. Where; M- Middle ordinate E- External ordinate e- Rate of super elevation

4.3.6 Widening on Curves and EmbankmentsThe use of long curves of tight radii should be avoided where possible, as drivers following the design speed will find it difficult to remain in the traffic lane. Curve widening reduces such problems. Widening on curves shall be provided to make operating conditions comparable to those on tangents. This is necessary as the wheel tracking width is increased. Curve widening is required on all standards of roads and should be sufficient to cater for the design vehicle. Table below gives the values to be adopted in the design. Curve widening shall generally be applied to both sides of the roadway. It should start at the beginning of the transition curve and be fully widened at the start of the circular curve. Widening is also required for Design Standards DS1 through DS5 at high fills for the psychological comfort of the driver. Widening for curvature and high embankment shall be added where both cases apply. The height of hill is measured from the edge of the shoulder to the toe of the slope.BY GROUP 1 Page 34


Table 4.9 Widening on Curves and High FillsRadius of curve Curve widening single lane Curve widening Two lane Height of fill(m) 0.0-3 3-6 6-9 Over 9 Over 9 Filling Widening Amount(m) 0 .3 .6 .9 .9

>250 120-250 60-120 40-60 20-40 L(where sight distance greater than curve length) M = L (2S L)/8R = SSD * D/40 Where D = Degree of curve Sample calculations Curve 1 L= 62.47 S= 53 SBY GROUP 1

)

LPage 42


D= 7.09 R = 80 R = 78.325 = 53 * 7.09 /40 = 9.390 M = R (1 Cos ) = 78.325 ( 1 Cos 9.38 ) = 1.05 m Curve 2 S = 30 L =25.32 R = 32 R = 30.325

M = L (2S L)/8R = 25.32 (2 * 30 25.32)/ 8 * 30.325 = 3.62 M Table 4.17 Setback distance on the horizontal curve Curve no 1 2 3 4 5 6 7 8 9 10 11 Design speed (KPH) 45 30 45 50 55 60 55 35 50 40 70 Length of curve ( m ) 62.47 25.32 17.14 37.24 69.49 18.49 52.03 35.25 44.52 35.79 54.84 Degree of curve 7.09 17.58 7.09 5.43 4.46 4.05 4.63 14.21 5.43 11.28 1.54 SSD 53 30 53 63 73 85 73 38 63 45 111 R 80 32 80 100 120 140 120 40 100 50 300 R 78.325 30.325 78.325 98.325 118.325 138.325 118.325 38.325 98.325 48.325 298.325 M 1.05 3.62 2.43 4.20 4.99 2.25 4.59 4.69 4.61 6.68 3.84

BY GROUP 1

Page 43


4.3.9 Transition CurvesThe characteristic of a transition curve is that it has a constantly changing radius. Transition curves may be inserted between tangents and circular curves to reduce the abrupt introduction of lateral acceleration. They may also be used between two circular curves. Drivers employ their own transition on entry to a circular curve and hence transition curves contribute to the comfort of the driver in only a limited number of situations. For large radius curves, the rate of change of lateral acceleration is small and transition curves are not normally required. It can also be argued that transition curves are not a requirement for certain roads, particularly those of lower classification, where there is insufficient justification for the additional survey and design work required. Another possible warrant would be to consider spirals for roads where a significant portion of the curves has a super elevation in excess of 60 percent of the maximum super elevation. For Ethiopian roads, transition curves are a requirement for trunk and link road segments having a design speed of equal to or greater than 80 km/hr. If the choice is made to employ a transition curve, the Euler spiral, which is also known as the clothoid, shall be used. The radius varies from infinity at that tangent end of the spiral to the radius of the circular arc at the circular curve end. By definition the radius at any point of the spiral varies inversely with the distance measured along the spiral. In the case of a combining spiral connecting two circular curves having different radii, there is an initial radius rather than an infinite value. The transition curve should be long enough to ensure that the radius can be changed at a slower rate. The rate of change of radial acceleration (C) therefore should be treated as a safety or comfort factor. The maximum value of C should generally accept to be in a range of 0.2 to 0.6 m/s2 . The length of transition curve Ls= V3/ (46.67R*C) For large radius of curve or small design velocity rate of change of lateral acceleration C is small. Thus, transition curve is not required. As it was mentioned above for Ethiopian road, transition curves are a requirement for Trunk and Link road regiments having design speed of equal to or greater than 80km/hr. For our case the road regiment is main access and design speed is less than or equal to 70km/hr. Therefore, no need of providing transition curve. 4.3.10 Super elevation Super elevation is the raising of outer edge or sloping upward towards the outside of the curve in order to counter balance the centrifugal force that acts on the vehicle. There are two forces acting on the vehicle that passes through the horizontal curve.BY GROUP 1 Page 44


1. centrifugal forces Force acting outward in radial direction. It depends on the moving vehicle speed and radius of the curve. i.e. mathematically F=mv2/r WhereF=centrifugal force m= mass of moving vehicle v= speed r= radius of curve 2. weight of the vehicle The weight of the vehicle act downward on moving vehicle it related to the road way super elevation and side friction developed between the tires and the pavement acts to balance the centrifugal force. i.e. mathematically e + f = v2/127R where e= rate of super elevation f= side friction v= velocity (km/hr) R= radius of the curvature The maximum super elevation rate applied on highways controlled by climate condition, terrain condition, type of area and frequency of very slow moving vehicles. It is common practice to utilize a low maximum rate of super elevation usually 4%. Similarly, either a low maximum rate of super elevation or no super elevation is employed with in important intersection areas or where there is a tendency to drive slowly because of turning and crossing moments, warning devices, and signals. Super elevation is a requirement for all standards of roads. The ERA geometric design manual recommends a maximum value of 8%.

BY GROUP 1

Page 45


Sample calculation Curve 1 V= 45 R= 80 f= 0.165 e= (v2/127R) f = (452/127*80)- 0.165 = 0.034 Which is less than the minimum ERA recommended value (0.04) therefore, we have to take the ERA value.Table 4.18 Super Elevation of curves Curve No Speed Radius Side friction Superelevation(% ) 1 45 80 0.16 5 4 2 30 32 0.17 0 5.1 3 45 80 0.16 5 4 4 50 100 0.16 0 4 5 55 120 0.15 5 5 6 60 140 0.15 0 5.2 7 55 120 0.15 5 5 8 35 40 0.17 0 7.1 9 50 100 0.16 0 4 10 40 50 0.17 0 8 11 70 300 0.14 0 4

4.3.10.1 Attainment Super elevation Runoff In alignment design with spirals the super elevation runoff is affected over the whole of the transition curve. The length of runoff is the spiral length with the tangent to spiral (TS) at the beginning and the spiral to curve (SC) at the end. The change in cross slope begins by removing the adverse cross slope from the lane or lanes on the outside of the curve on a length of tangent just ahead of TS (the tangent run out). Between the TS and SC (the super elevation runoff) the traveled way is rotated to reach the full super elevation at the SC. This procedure is reversed on leaving the curve. By this design the whole of the circular curve has full super elevation, as shown in figure.

BY GROUP 1

Page 46


In design of curves without spirals the super elevation runoff is considered to be that length beyond the tangent run out. Empirical methods are employed to locate the super elevation runoff length with respect to the point of curvature (PC).Current design practice is to place approximately two-thirds of the runoff on the tangent approach and one-third on the curve, as shown in Figure

BY GROUP 1

Page 47


In providing of run out length, ERA manual provide run out length. At the same time there is a calculated v value from the two we provide the less value. The Ethiopian transport Construction Design Enterprise (TCDE) has recommended the following table relating the rate of raising the out late edge with the design speed. Table 4.19 Rate of Raising from ERA manual Design Speed(km/hr) 80 60 50 40 V:H Ratio 1:200 1:170 1:155 1:140

From the design speed of our curve and the rate of rising given the rate of rising of our curves tabulated as follows.

BY GROUP 1

Page 48


Table 4.20 Rate of Rising of Curves Curve no 1 2 3 4 5 6 7 8 9 10 11 Mathematically Design speed (KPH ) 45 30 45 50 55 60 55 35 50 40 70 V.H ratio 1: 147 1:125 1:147 1:155 1:162 1:170 1:162 1:132 1:155 1:140 1:184

LT = w/2 * (e + Ncr/ slope) Where LT = total run off length W = total width e = super elevation rate Ncr = normal crown (2.5 %) Slope = in v: H ratio L1 = Ncr * w/ slope Where L1 = the point where super elevation is equal to the cross fall distance from where super elevation start

BY GROUP 1

Page 49


Sample calculationChainage of BC = 0 + 400.26 Radius R Design speed=45Kph No of lane=2 For DS4 normal and shoulder cross fall =2.5% Road width= 6.7m Maximum super elevation= 8% Rate of super elevation from ERA manual =4% Rate of application of super elevation = 1:147 Run of length Lt = [w/2(e+Ncr)]/slope = [6.7/2(0.04+0.025)]/(1:147) = 15m Recommended Lt=37m Provide the calculated value Lt=15m Calculated run off length in the tangent= 2/3Lt =2/3*15 =10m Length of run off on the curve =1/3*15=5m Length where super elevation is equal to cross fall from where it start L1= Ncr*w/slope =0.025*6.7/1:147 =24.6mBY GROUP 1 Page 50

=80m

= 1/3 Lt


Chainage of normal crown= Chainage of BC Provided value of run off = 0+400.26-15 =0+385.26 Chainage of RC = Chainage of Normal crown L1 =0+385.26-24.6 =0+360.66 Chainage of BFSE (beginning of full super elevation) = Chainage of PC+Lt/3 =400.26+5 =405.26 Chainage of EFSE (end of full super elevation) = Chainage BC+Lc-2(Lt/3) =400.26+62.47-10 =452.73 Chainage of normal crown= Chainage ET+ Provided value of run out =0+462.73+15m =0+477.73m Chainage of RC= Chainage of normal crown-L1 =0+477.73-24.6 =0+453.13

BY GROUP 1

Page 51


Table 4.21 Alignment of Super elevation, Run off C. No 1 2 3 4 5 6 7 8 9 10 11 radius e(%) Runoff RL Lt Lt/3 2Lt/3 Chainage Chainage Chainage Chainage Chainage Chainage (V:H) (m) (m) NC RC BFSE EFSE NC RC 80 32 80 100 120 140 120 40 100 50 300 4 5.1 4 4 5 5.2 5 7.1 4 8 4 1:147 1:125 1:147 1:155 1:162 1:170 1:162 1:132 1:155 1:140 1:184 37 38 37 42 39 47 39 36 42 41 44 15 43 47 53 53 59 53 49 53 49 56 5 14 15 17 17 19 17 16 17 16 18 10 29 31 35 35 39 35 32 35 32 37 L1

0+385.26 0+360.66 0+405.26 0+452.73 0+477.73 0+453.13 24.60 0+444.83 0+423.89 0+497.49 0+478.83 0+566.14 0+545.20 20.94 0+647.87 0+623.25 0+700.79 0+670.17 0+780.90 0+756.28 24.62 0+749.19 0+723.23 0+809.02 0+792.77 0+930.44 0+904.48 25.96 0+909.02 0+881.48 0+965.75 0+982.05 1+056.51 1+028.97 27.54 1+305.77 1+276.87 1+372.51 1+331.78 1+518.26 1+482.36 28.90 1+662.36 1+634.82 1+719.09 1+717.93 1+832.39 1+804.85 27.54 1+767.27 1+744.83 1+818.69 1+805.68 1+904.52 1+882.08 22.44 1+849.93 1+823.58 1+909.76 1+900.79 2+038.45 2+012.10 26.35 2+161.67 2+137.87 2+219.09 2+205.62 2+319.46 2+295.66 23.80 2+572.65 2+541.37 2+635.55 2+633.69 2+815.49 2+784.21 31.28

BY GROUP 1

Page 52


4.3.10.2 Shoulder Super elevation Figure depicts shoulder super elevation rates corresponding to carriageway super elevation rates. The figure shows that on the low side (inner shoulder) of super elevated curves, the shoulder super elevation matches the roadway super elevation. On the high side (outer shoulder), the super elevation is set such that the grade break between the roadway and the shoulder is 8 percent. An exception to this occurs at a maximum super elevation of 8 percent, where the resultant shoulder super elevation would be an undesirable flat configuration. Here the super elevation is set at -1% to drain the shoulder.

BY GROUP 1

Page 53


4.4 VERTICAL ALIGNMENT 4.4.1 INTRODUCTIONThe vertical alignment is the elevation or profile of the center line of the road, which comprises a series of tangent grades connected by parabolic vertical curves. The most desirable design should provide smooth riding quality and good visibility with minimum amount of earth work. Criteria for the Design of a vertical Alignment In the establishment of a grade the act should be balanced against the fill without a great deal of borrow or an excess of cut material to be wasted. Long distances between points of intersection, with long curves between grade tangents to provide smooth riding qualities and good usability. The grade should follow the general terrain and rise or fall in the direction of the existing drainage. All earth work hauls should be moved in a downhill direction if possible and within relatively short distances from the origin, due to the expenses of moving large quantity soil. Maintain higher grades, in rock cuts and in flat, low-lying or swampy areas, with respect to the existing ground line. Avoidance of very short sag vertical curves. Avoidance of short drop immediately before a long up grade. Avoidance of the combination of two vertical curves in the same direction. Where defects occur, phasing shall be achieved either by separating the curves or by adjusting their lengths such that vertical and horizontal curves being at a common station and end at a common station. In the same cases, depending on the curvature, it is sufficient if only one end of each of the curves is at a common station. The two major aspects of vertical alignment are vertical curvature, which is governed by sight distance criteria, and gradient, which is related to vehicle performance and level of service. The following text gives the formula and features of the vertical curve; gives values for maximum and minimum gradients; indicates gradient requirements through villages; develops the criteria for incorporation of a climbing lane; and provides vertical clearance standards.BY GROUP 1 Page 54


4.4.2 Vertical Curve FormulaVertical curves are required to provide smooth transitions between consecutive gradients.The main criteria used for designing vertical curves are:-

Provision of Minimum stopping sight distance if it is possible and economical minimum passing sight distance It should have good appearance (aesthetically) It should provide good comfort for drivers It should provide good drainage for sag curve It should avoid miss-phasing with horizontal curve. The simple parabola is specified for these. The parabola provides a constant rate of change of curvature, and hence acceleration and visibility, along its length and has the form: Elevation of PVC= Elevation of PVI-g1*L/2 Where:r = rate of change of grade per section (%) g1 = starting (%) g2 = ending grade (%) L = length of curve (horizontal distance m) Y= rx2 +g1x + Elevation of PVC y = elevation of a point on the curve x = distance in stations from the BVC (meters/100) BVC = beginning of the vertical curve EVC = end of the vertical curve A related formula is: Where y = vertical distance from the tangent to the curve (meters) x = horizontal distance from the start of the vertical curve (meters) G = algebraic difference in gradients (%) L = length of vertical curve (meters).

BY GROUP 1

Page 55


4.4.3 Types of vertical curveCrest and Sag Curves The formulae for design of crest and sag vertical curves can be rather complex to apply, and thus the design is best accomplished through the application of a computer program, or by use of design charts. Figures and show the minimum length requirements for crest and sag curves, respectively, for differing design speeds and algebraic differences in grade. Example: Starting grade = -6%, ending grade = +2%, design speed = 100 km/hr. Algebraic difference in grade = 8%, sag curve. From Figure 9-2: 400-meter length The minimum lengths of crest and sag curves have been designed to provide sufficient stopping sight distance. The design is based on minimum allowable "K" values, as defined by the formula: K = L/A Where K = limiting value, horizontal distance required to achieve a 1% change in grade L = length of vertical curve (m) A = Algebraic difference in approach and exit grades (%) Minimum lengths of crest and sag vertical curves have been recommended based on design speeds and stopping sight distance requirements. They provide for ride comfort, appearance, and most importantly, safety. These are shown in Tables4-1 and 4-2, respectively, in terms of K values. Example: Design Speed = 100 km/h, Sag Curve from Table 9-2 K= 51 Algebraic difference in grades 2-(-6) = 8% Minimum length L = AK = 8(51) = 408 meters 4.4.4Minimum Lengths of Vertical Curves Especially for trunk and link roads, where the algebraic difference between successive grades is often small, the intervening minimum vertical curve, applying in the above formulae, becomes very short. This can create the impression of a kink in the grade line. For this reason, where the algebraic differences in grade are less than 0.5 percent, a minimum curve length is recommended for purely aesthetic reasons. A minimum length of 200 meters is recommended, except in mountainous or escarpment terrain. However, for lower standard roads (DS6-DS10), no minimum length should be specified. In these cases, the curve lengths should be kept to a minimum to enhance drainage capabilities, and the curve lengths should match as a minimum the K values given in Tables through for stopping sight distance. Where the difference in grade is less than 0.5 percent, the vertical curve is often omitted. For higher volume roads, a minimum length should be considered between vertical curves. If the vertical alignment is allowed to contain many curves of short length, the result can be a hidden dip profile, and/or a roller coaster type profile, as indicated in Figure.BY GROUP 1 Page 56


Table4.22: Minimum Values for Crest Vertical Curves

Table 4-23 : Minimum Values for Sag Vertical Curves

BY GROUP 1

Page 57


Figure 4-2: Hidden Dip and Roller Coaster Profiles BY GROUP 1 Page 58


Figure 4-3: Minimum Values for Crest Vertical Curves

BY GROUP 1

Page 59


Figure 4-4: Minimum Values for Sag Vertical Curves

BY GROUP 1

Page 60


Sample calculation and checking the minimum length of the curve For sag curve no-1 K =20 A =11.22 L min=AK=20x11.22=224.4 and provided L=224.4 For crest curve no-3 K=43 A=2.48 L min=43x2.48=106.64,L provided=339.86 4.5 Gradient Gradient is the rate of rise or fall along the length of the road with respect to the horizontal. It is expressed as percentage. The ascending gradient are given (+ve) signs and descending gradients are given (-ve) signs. In the analysis of grades and grade control, one of the most important considerations is the effect of grades on the operating costs of the motor vehicle. An increase in gasoline consumption, a reduction in speed, and an increase in emissions and noise are apparent when grades are increased. Minimum grades are governed by drainage conditions.

Maximum GradientsVehicle operations on gradients are complex and depend on a number of factors: severity and length of gradient; level and composition of traffic; and the number of overtaking opportunities on the gradient and in its vicinity. For very low levels of traffic flow represented by only a few four-wheel drive vehicles other references advocate a maximum traversable gradient of up to 18 percent. Small commercial vehicles can usually negotiate an 18 per cent gradient; whilst two-wheel drive trucks can successfully manage gradients of 15-16 per cent except when heavily laden. However, the vehicle fleet in Ethiopia is composed of a high percentage of vehicles that are underpowered and poorly maintained. Certain existing roads in fact are avoided andBY GROUP 1 Page 61


underutilized by traffic due to an inability to ascend the existing grades. The ERA finds it is in a position where it has no choice but to limit gradients based on the design vehicle of existing fleet, although this translates into an added cost to develop the road infrastructure. Maximum vertical gradient is therefore and extremely important criterion that greatly effects both the serviceability and cost of the road. Table 4.24: Maximum Gradients Topography DS1 to DS3 D Flat Rolling Mountainous Escarpment Urban 3 4 6 6 6 A 5 6 8 8 8 Maximum Gradient (%), for Design Standard DS4 & DS5 D 4 5 7 7 7 A 6 7 9 9 9 DS6 to DS8 D 6 7 10 10 7 A 8 9 12 12 9 D 6 7 13 13 7 DS9 A 8 9 15 15 9 DS10 D 6 7 14 14 7 A 8 9 16 16 9

Note: First value shown is desirable value (D), second is absolute value (A). When gradients of 10 percent or greater are reached, consideration should be given to the possibility of paving these steep sections to enable sufficient traction to be achieved, as well as for pavement maintenance reasons. However, this is clearly not practical for all classes of roads, particularly at lower traffic volumes. There may be cases where paving greater than 10 percent will be economical. This depends on the standard and the service of the road to be provided. As traffic flow increase, the economic dis-benefits of more severe gradients, measured as increased vehicle operating and travel time costs, are more likely to result in economic justification for reducing the severity and/or length of a gradient. On the higher design classes or road, the lower maximum recommended gradients reflect these economics. However, a separate economic assessment of alternatives to long or severe gradients should be undertaken where possible or necessary. Standards for desirable maximum gradients were set to assure user comfort and to avoid severe reductions in the design speed. If the occasional terrain anomaly is encountered that requires excessive earthworks to reduce the vertical alignment to the desirable standard an absoluteBY GROUP 1 Page 62


maximum gradient can be used. Employment of a gradient in excess of the desirable maximum can only be authorized through the employment of a Departure from Standard. For our design standard of DS4 and ROLLING terrain type, a desirable maximum gradient of 5% and an absolute gradient of 7% have been recommended and for the curve no-1 and curve no-4 a gradient of 11.22% and 10.58% are provided respectively with the climbing lane. Maximum Gradients at Switchbacks Where switchback curves are unavoidable in mountainous or escarpment terrain, there is a need to reduce the maximum allowable gradient at any point through the curve. The maximum allowable gradient through a switchback curve is 4 percent for road standards DS1-DS5, and 6 percent for DS6-DS10. Minimum allowable gradient is 0.5%. Corresponding crest and sag curves approaching the switchback curve must meet the requirements of subsections 9.2 and 9.3, and the transitions must be completed outside of the switchback curve. The sag curve above the switchback shall be made as long as possible to allow ascending vehicles to accelerate at the flatter grade when leaving the switchback. Minimum GradientsThe minimum gradient for the usual case is 0.5 percent. However, flat and level gradients on uncurbed paved highways are acceptable when the cross slope and carriageway elevation above the surrounding ground is adequate to drain the surface laterally. With curbed highways or streets, longitudinal gradients should be provided to facilitate surface drainage.

Gradients through VillagesIn many instances the natural grade level is flat through villages. The adjacent roadside ditches in such circumstances can readily become clogged and ineffective. It is also the case that they are deliberately blocked to provide access to adjacent property or to channel flow for agricultural use. These practices lead to saturation of the sub-grade and hence pavement failure, and should be avoided.

Critical length of gradientCritical length may be defined at the point at which a truck reaches a certain speed or the point at which it has lost a certain amount of speed. Critical length of gradient is considered to be the maximum length of a designated upgrade upon which a loaded truck can operate without unreasonable reduction in speed.Critical length of gradient is, to some extent, dependent on the gradient of the approach; a downhill approach will allow vehicles to gain momentum and increase the critical length. In general, the critical length of gradient decreases, as gradient increases.

BY GROUP 1

Page 63


Climbing Lanes A climbing lane is an effective means of reducing the impact of a steep gradient. A climbing lane is an auxiliary lane added outside the continuous lanes and has the effect of reducing congestion in the through lanes by removing slower moving vehicles from the traffic stream. It also enhances road safety by reducing the speed differential in the through lane. The requirements for climbing lanes are therefore based on road standard, speed and traffic volume. Benefits from the provision of a climbing lane accrue because faster vehicles are able to overtake more easily, resulting in shorter average journey times, reduced vehicle-operating costs, and increased safety. Benefits will increase with increases in gradient, length of gradient, traffic flow, the proportion of trucks, and reductions in overtaking opportunities. The effect of a climbing lane in breaking up queues of vehicles held up by a slow moving truck will continue for some distance along the road. Climbing lanes must be considered for roads when present traffic volumes are greater than 400 ADT. Thus the application of climbing lanes is limited particularly to trunk and link roads. Table 9-4 is prepared according to the criteria that a 20 km/h speed reduction is expected for a truck. It is used in the design to indicate locations where climbing lanes are recommended. A climbing lane layout is shown in Figure 4.5. Climbing lanes must be clearly marked and, where possible, should end on level or downhill sections where speed differences between different classes of vehicles are lowest to allow safe and efficient merging maneuvers. The introduction and termination of a climbing lane shall be effected by tapers of lengths of 100 meters. The tapers shall not be considered as part of the climbing lanes. The starting point of the grade can be approximated as a point halfway between the preceding vertical point of intersection and the end of the vertical curve.

BY GROUP 1

Page 64


Table 4.25: Climbing Lanes Design Class Gradient (%) DS2 &3 DS2, 3 & 4 DS2, 3 & 4 DS2, 3 & 4 DS2, 3 & 4 DS2, 3 & 4 DS2, 3 & 4 DS4 DS4 4 5 6 7 8 9 10 11 12 Critical Length of Gradient above which a Climbing Lane is required (m) 300 240 200 170 150 130 Required Required Required Maximum Desirable Length of Gradient (m) 900 800 700 600 500 400 400 400 400

There is a problem in the application of a climbing lane in escarpment terrain. Here the carriageway and shoulder widths may have been reduced, and thus a climbing lane will increase the roadway width. Consideration must be given to a balance between the benefits to traffic and the initial construction cost. In sections requiring heavy side cut, the provision of climbing lanes may be unreasonably high in relation to the benefits. Reduced level of service over such sections is an alternative. The climbing lane is sometimes not effectively utilized, especially when traffic flows are heavy, because the drivers of slower vehicles fear that they will not be allowed to merge with the faster vehicles where the climbing lane ends. The preferred layout forces faster vehicles to merge with the slower, thus allaying this fear to some extent. This layout is preferred based purely on that fact that a vehicle can merge more readily with a slower-than with a faster-moving stream of traffic (see Figure4.5).BY GROUP 1 Page 65


The performance characteristics of a heavy vehicle are such that, for a particular gradient, the vehicle speed will reduce to final ambient speed that can be maintained by that vehicle on that grade. This limits, in most references, any discussion on the maximum length allowable at a given grade even considering the employment of a climbing lane. However, in the interests of factors such as vehicle operating costs and travel time losses, the absolute recommended maximum lengths at any given grade are also indicated in the last column of Table 9-4. When these distances are reached, it is necessary to design a relief gradient of less than 6 percent between steep sections. The relief gradient shall extend a minimum of 100 meters.

These values have also taken into consideration the safety factors associated with the increase in speed resulting in the descent of steep grades. Although they may mitigate the safety hazard, they do not eliminate it. For example, a non-braking "typical" heavy truck will accelerate from 0 km/hr to 90 km/hr over a distance of 500 meters at a descending grade of 5 percent. This emphasizes the need to provide warning signs for such vehicles at all long continuous grades.

BY GROUP 1

Page 66


Figure 4.5: Layout for Climbing Lane BY GROUP 1 Page 67


Vertical ClearancesBridges over water shall normally have a minimum clearance height according to Table 7-5, unless a refined hydraulic analysis has been made. The standard minimum headroom or clearance under bridges or tunnels shall be 5.1m for all classes of roads. This clearance should be maintained over the roadway(s) and shoulders. Where future maintenance of the roadway is likely to lead to a rising of the road level, then an additional clearance of up to 0.1m may be provided. Light superstructures (i.e. - timber, steel trusses, steel girders, etc) over roadways shall have a clearance height of at least 5.3m. See ERA's Bridge Design Manual-2001 for further reference. Table 4.26: Vertical Clearance from Superstructure to Design Flood Level (DFL)

Design Flow at Bridge (m3/s) 5 to 30 30 to 300 >300

Vertical Clearance (m) 0.6 0.9 1.2

Source: ERA Bridge Design Manual-2001

Underpasses for pedestrians and bicycles shall not be less than 2.4m. For cattle and wildlife, underpasses shall be designed as the normal height of the actual kind of animal plus 0.5m, and for horse-riding the clear height shall be not less than 3.4m. Bridges above railways shall have a clearance height of at least 6.1m- if not otherwise stated- to facilitate possible future electrification. Over existing pipe culverts and box culverts, the roadway elevation cannot be less than as indicated in the ERA Drainage Design Manual- 2001.

BY GROUP 1

Page 68


4.4.6 PHASING ALIGNMENT

OF

HORIZONTAL

AND

VERTICAL

4.4.6.1 Alignment Defects Due to Mis-phasing Phasing of the vertical and horizontal curves of a road implies their coordination so that the line of the road appears to a driver to flow smoothly, avoiding the creation of hazards and visual defects. It is particularly important in the design of high-speed roads on which a driver must be able to anticipate changes in both horizontal and vertical alignment well within the safe stopping distance. It becomes more important with small radius curves than with large. Defects may arise if an alignment is mis-phased. Defects may be purely visual and do no more than present the driver with an aesthetically displeasing impression of the road. Such defects often occur on sag curves. When these defects are severe, they may create a psychological obstacle and cause some drivers to reduce speed unnecessarily. In other cases, the defects may endanger the safety of the user by concealing hazards on the road ahead. A sharp bend hidden by a crest curve is an example of this kind of defect. Types of Mis-Phasing and Corresponding Corrective Action When the horizontal and vertical curves are adequately separated or when they are coincident, no phasing problem occurs and no corrective action is required. Where defects occur, phasing may be achieved either by separating the curves or by adjusting their lengths such that vertical and horizontal curves begin at a common station and end at a common station. In some cases, depending on the curvature, it is sufficient if only one end of each of the curves is at a common station. Cases of mis-phasing fall into several types. These are described below together with the necessary corrective action for each type. 4.4.6.2 Vertical Curve Overlaps One End of the Horizontal Curve If a vertical curve overlaps either the beginning or the end of a horizontal curve, a drivers perception of the change of direction at the start of the horizontal curve may be delayed because his sight distance is reduced by the vertical curve. This defect is hazardous. The position of the crest is important because the vehicles tend to increase speed on the down gradient following the highest point of the crest curve, and the danger due to an unexpected change of direction is consequently greater. If a vertical sag curve overlaps a horizontal curve, an apparent kink may be produced, as indicated in Figures. The defect may be corrected in both cases by completely separating the curves. If this is uneconomic, the curves must be adjusted so that they are coincident at both ends, if the horizontal curve is of short radius, or they need be coincident at only one end, if the horizontal curve is of longer radius.

BY GROUP 1

Page 69


Insufficient Separation Between The Curves If there is insufficient separation between the ends of the horizontal and vertical curves, a false reverse curve may appear on the outside edge-line at the beginning of the horizontal curve. Corrective action consists of increasing the separation between the curves, or making the curves concurrent. 4.4.6.3Both Ends Of The Vertical Curve Lie On The Horizontal Curve If both ends of a crest curve lie on a sharp horizontal curve, the radius of the horizontal curve may appear to the driver to decrease abruptly over the length of the crest curve. If the vertical curve is a sag curve, the radius of the horizontal curve may appear to increase.. The corrective action is to make both ends of the curves coincident as in Figure or to separate them. 4.4.6.4 Vertical Curve Overlaps BothEnds Of The Horizontal Curve If a vertical crest curve overlaps both ends of a sharp horizontal curve, a hazard may be created because a vehicle has to undergo a sudden change of direction during the passage of the vertical curve while sight distance is reduced. The corrective action is to make both ends of the curves coincident. If the horizontal curve is less sharp, a hazard may still be created if the crest occurs off the horizontal curve. This is because the change of direction at the beginning of the horizontal curve will then occur on a downgrade (for traffic in one direction) where vehicles may be increasing speed. The corrective action is to make the curves coincident at one end so as to bring the crest on to the horizontal curve. No action is necessary if a vertical curve that has no crest is combined with a gentle horizontal curve. If the vertical curve is a sag curve, an illusory crest or dip, depending on the hand of the horizontal curve will appear in the road alignment. The corrective action is to make both ends of the curves coincident or to separate them. Table 4.27 Intersection points Curve Curve PVC no type Station 1 2 3 4 Sag Sag Crest Sag 0+175.38 1+429.31 2+199.93 2+794.16 PVI Elevation Station (m) 3264.67 3299.58 3335.34 3330.97 0+270.12 1+539.66 2+369.86 2+957.47 Elevation on curve (m) 3266.91 3301.08 3341.20 3335.29 Elevation on tangent(m) 3264.66 3299.56 3344.55 3329.96 PVT Station 0+364.86 1+650.00 2+539.79 3+120.79 Elevation (m) 3269.15 3302.57 3340.33 3339.61

BY GROUP 1

Page 70


Table4.28 Grade, distance and station elevation Curve no 1 2 3 4 Grade % G +11.22 +5.42 -2.48 +10.58 Distance 319.13 830.20 587.62 182.53 Station & Elevation High Low ---------------------------- 1+433.21 2+432.98 -------------------- 2+856.26

Elevation ----------3299.66 3341.66 3373.24

Table 4.29 safety distances Curve no 1 2 3 4 WherePVC=the point at which the tangent grade ends and vertical curves begins PVT =the point at which the vertical curve ends and tangent grade beginsPVI=The which where the extension of two tangent grade intersect L = the horizontal distance from PVC to the PVT. E = the vertical distance between the PVI and the road way surface along the vertical curve

L (m) 224.40 220.69 339.86 326.64

K 20 40 43 25

E +2.24 +1.52 -3.36 +5.33

SSD (m) -----------131.84 -------

PSD (m) -----------201.66 --------

Design speed (KM/hr) -----25 20 ------

Head light (m) 95.07 168.18 -----113.67

K =the rate of vertical curveSSD=stopping sight distance PSD=passing sight distance

4.4.7 CROSS SECTION ELEMENTSIntroduction A cross-section will normally consist of the carriageway, shoulders or curbs, drainage features, and earthwork profiles. These terms are defined in the Definition portion of the manual text; major elements are repeated here for clarity:

BY GROUP 1

Page 71


Carriageway- the part of the road constructed for use by moving traffic, including traffic lanes, auxiliary lanes such as acceleration and deceleration lanes, climbing lanes, and passing lanes, and bus bays and lay-byes. Since we are designing for a volume of rural road of design standard DS4, the ERA manual provide carriage way width of 6.7m. Lane Widths A feature of a highway having great influence on safety and comfort is the width of the carriageway. Lane widths of 3.65m are used for Design Classes DS1 and DS2. The extra cost of 3.65 m above that for 3.0 m is offset to some extent by a reduction in cost of shoulder maintenance and a reduction in surface maintenance due to lessened wheel concentrations at the pavement edges. The wider 3.65m lane also provides desired clearances between large commercial vehicles on two-way rural highways. Narrower lanes are appropriate on lower volume roads. Auxiliary lanes at intersections often help to facilitate traffic movement. Such added lanes For our DS4 design classes a 3.35m lane width is provided. Shoulders A shoulder is the portion of the roadway contiguous to the carriageway for the accommodation of stopped vehicles; traditional and intermediate non-motorized traffic, animals, and pedestrians; emergency use; the recovery of errant vehicles; and lateral support of the pavement courses. Shoulder widths vs. design standards, terrain type, and urban/rural environment are presented in . They vary from no shoulder on minor rural roadswhere there is no surfacing, to a 1.5-3.0 m or even greater sealed shoulder on major roads depending on the terrain and design classification. Wider configuration ns cater to the need for a parking lane in urban/semi-urban areas where paved carriageways exist. For unpaved carriage ways, the shoulders are included in the carriageway width given in Table. Where the carriageway is paved, the shoulder should also be sealed with a single bituminous surface treatment. This has several advantages. It would prevent edge raveling and maintenance problems associated with parking on a gravel shoulder. It would provide paved pace for vehicular parking outside of the traffic flow. It would provide a better surface for vehicles experiencing emergency repairs. It would also provide for the very heavy pedestrian traffic observed in the villages, traffic that would otherwise, especially during inclement weather, use the roadway. All of the above also indicate an improvement in terms of roadway safety. The sealed shoulder width may increase to 3.5 meters in urban/semi-urban areas where a provision for a parking lane is required. The degree of urbanization determines whether a parking lane is required. In urban areas, the shoulders should be paved rather than sealed. For Design Standard DS3 roads, the engineer often needs to be observant and use his discretion in defining the width of the shoulder. On market days, the urban center can cause a high volume of pedestrian traffic commencing a significant distance outside of the center, indicating a need to consider the higherBY GROUP 1 Page 72


limit over this distance. The actual shoulder width provided shall be determined from an assessment of the total traffic flow and level of non motorized traffic for each road section. In cases where terrain is severe, the existing roadway width is narrow, and where the shoulder width could only be maintained through an excessive volume of earthwork e.g. at escarpment conditions, standards can be reduced through the Departure from Standard process. According to ERA manual 1.5m is provided for both flat and rolling terrain for design classes of DS4. Roadway- consists of the carriageway and the shoulders, parking lanes and viewing areas. A 9.7m road way is provided with carriage way of 6.7m and two side shoulder of 3m for design classes of DS4. Normal Cross fall Normal cross fall (or camber, crown) should be sufficient to provide adequate surface drainage whilst not being so great as to make steering difficult. The ability of a surface to shed water varies with its smoothness and integrity. On unpaved roads, the minimum acceptable value of cross fall should be related to the need to carry surface water away from the pavement structure effectively, with a maximum value above which erosion of material starts to become a problem. The normal cross fall should be 2. percent on paved roads and 4 percent on unpaved roads. Shoulders having the same surface as the roadway should have the same normal cross fall. The normal crown slope of 2% is provided for our design classes of DS4. Side slopes and Back slopes The side slopes and back slopes were designed to insure the stability of the road way and to provide a reasonable opportunity for recovery of an out of central vehicle. The selection of a side slope and back slope is dependent on : Safety consideration Economic consideration Height of cut or fill The material of the site drainage

BY GROUP 1

Page 73


The most applicable guideline recommended on ERA Geometric Design manual is given below and directly applied.

Table4.30: side and back slope ratio (V:H) Height of slope Material Cut 0.0-1.0m 1.0-2.0m >2.0m 1:4 1:3 1:2 Fill 1:4 1:3 1:2 1:3 1:2 1:1.5 Side slope Back slope

For our design classes of DS4, 1:3m side slope and 1:2m back slope is provided Road side Ditches A summary of minimum ditch dimensions is given as follows. Minimum depth ofditches should be 0.6m in mountainous and escarpment terrain, and 1.0m elsewhere, using av-ditch configuration. The side slope and back slope of ditches should generally be no lessthan 1:2; however, these slopes should conform to the slopes given in Table .Side drains should be avoided in areas with expansive clay soils such as black cotton soils. Where this is not possible, they shall be kept at a minimum distance of 4-6m from the toe ofthe embankment, dependent on functional classification (6m for trunk roads). The ditch in this instance should have a trapezoidal, flat-bottom configuration with side slope of 1:3m and back slope of 1:2m for design cases of DS4 is provided. Right- of way Right of way or road reserve is provided in order to accommodate road width and to enhance the safety, operation and appearance of the roads. The width of right of way depends on the cross-section elements of the high way, topography and either physical controls together with economic consideration. Right of ways will be equidistant from the center line of the road to the left and to the right of the carriage way. Although it is desirable to acquire sufficient right of way to accommodate all elements of the cross-section, width should be limited to minimum practical amount.

BY GROUP 1

Page 74


ERA-recommends a 50m of right of way for road classes of DS4. But ,the minimum of 30m right of way was provided. The distance across the carriage way from building line to building line should be a minimum of 30m.

BY GROUP 1

Page 75


CHAPTER FIVE EARTH WORK

5.1 Earthwork Quantities and Mass Haul DiagramIntroductionThe topic

Documents

High Way Project 2010 (Summer Group 1)