Month: September 2017

## Ribbon Development

The constructional development, occurring on the side of a road in the form of shops, hotels, or other buildings is called Ribbon development.

Due to ribbon developments the cost of land adjoining the road increases which ultimately increases the cost of land acquisition at the time of road development in the future. It may also create difficulties in acquiring lands required for the further development of an existing road.

Transition Curve In Highway-Objects || Types || Essential Requirement

# Average Daily Traffic & Annual Average Daily Traffic

It is the average 24-hour volume at a given location for some period of time less than a year. For this minimum of 7 days count is done to include the daily variation like on Saturday and Sunday.

It is the average 24-hour traffic volume at a given location over a full 365 days. Total traffic and classified traffic are calculated. It helps in deciding the relative importance of a route and road development. It includes seasonal variation also.

# Super Elevation

## What is Super Elevation?

When a vehicle is moving on a curved path it is subject to an outward force known as centrifugal force. In order to counteract the effect of centrifugal force, the outer edge of the pavement is raised with respect to the inner edge. This transverse inclination provided to the pavement surface is known as superelevation or cant or banking.

Method of Providing SuperElevation

Analysis of Superelevation Formula as Per IRC

Maximum and Minimum SuperElevation

The rate of rise or fall along the length of the road with respect to the horizontal is called grade or gradient.

In other words, it is the longitudinal slope provided to the formation level of a road along its alignment. It is expressed as the ratio of 1 in n (1 vertical unit to n horizontal units). It is also expressed as a percentage.

The gradient may also be expressed in degrees of elevation or depression above or below the horizontal plane. Mathematically, the gradient can be expressed as follows:
or
gradient =  (1/n) * 100 Percent.

Let’s, take an example.

In the above picture, the horizontal distance is 1000 m, and the verticle distance or rise or fall is 25 m. From the definition, we can write,
Gradient = 25 : 1000 = 1 : 40.
Or, 1 in 40.
Or, (1/40) * 100 = 2.5 percent

# 4 Types Of Camber || Road Camber Types

The following 4 types of camber are generally provided to the road surface.

1. Composite camber.
2. Sloped or Straight camber.
3. Two straight line camber.
4. Barrel camber.

## 1. Composite camber

It consists of two straight slopes from the edges with a parabolic or circular crown.

## 2. Sloped or Straight camber

It consists of two straight slopes from the edges joining at the centre of the carriageway. This type of camber is very simple and can be easily constructed. For cement concrete roads, a straight camber is the most suitable camber type.

## 3. Two straight line camber

It consists of two straight lines steeper near the edges and flatter near the crown, this type of camber is considered to be the best for Indian roads.

## 4. Barrel camber

It consists of a continuous curve either elliptical or parabolic. This type of camber is preferred for roads used by fast-moving vehicles.

Barrel camber is common for bituminous pavement. And remember that the barrel camber is not possible to construct in the case of concrete roads, hence this type of camber is not used for concrete roads.

## Method Of Providing Camber

The required camber is provided to the subgrade, for providing the desired amount and shape of camber, templates or camber boards are prepared with the specified camber. the material to be used in the subgrade is spread and hand paced to the shape of the desired camber.

The rolling is then started from the edge towards the centre. Then checking of the top surface is done with the help of templates or camber boards. the deficiency by spreading or removing the material as required.

## Purposes/Objects Of Providing Camber

Camber is provided on the road surface to achieve the following objects:

1. To drain off rainwater from the surface of the carriageway as quickly as possible.

3. To regulate the vehicles to their proper lanes.

4. To improve the architectural appearance of the roadway.

Functions Of Camber Or Cross Slope

Kerbs

# Camber Or Cross Fall Or Cross Slope

## Camber Or Cross Fall Or Cross Slope

The convexity provided to the road surface in the transverse direction, to drain off rainwater is known as camber or cross fall or cross slope.

Usually, camber is provided on the straight road by raising the centre of the carriageway with respect to the edges.

The rate of camber is usually designated by 1 in n (vertical: horizontal). It is also expressed as a percentage.

Cambers are classified as 4 types:

1. Composite camber.
2. Sloped or Straight camber.
3. Two straight line camber.
4. Barrel camber.

Audio of Camber

Types of Camber

# Design Speed – Highway Engineering

## Design Speed

The maximum safe speed of vehicles assumed for a geometrical design of a highway is known as design speed.

The design speed dependent upon the following factors

1. Types and conditions of the road surface.

3. Nature and intensity of traffic.
4. Types of the curve along the road.

5. Sight distance required.
6. Nature of the country.

The design speed is the most important factor controlling the geometric design elements of highways, the design speed is decided considering the overall requirements of highways.

There are different speed standards have been assigned depending upon the importance, or class of the road.

Recommended Design Speed on Urban Roads

# 11 Factors Affecting The Rate of Water Demand

Following 11 factors affecting the rate of water demand:

1. Size of city
2. Climatic condition
3. Due to Habits
4. Industrial and commercial activity
5. Quality of water supply
6. The pressure in distribution systems
7. Development of sewage facility
8. System of supply
9. Cost of water
10. Policy of metering
11. Living Standards

## 1. Size of city

Large cities mean they have large populations with lots of amenities. So, large cities require more water as compared to small cities.

## 2. Climatic condition

People living in hot climates need more water than those living in cold climates. This is because a hot climate makes people thirsty more than a cold climate. Not only this reason but also require more water for gardening, street plant watering, park. Also, the duration and frequency of human bathing is greater than in cold weather.

## 3. Due to Habits

Some bad habits can increase the rate of water demand like – Leaving water taps open, not fixing leakage of water, washing things repeatedly for no reason, watering plants unnecessarily, etc. But, opposite habits of the above points can decrease the rate of water demand.

## 4. Industrial and commercial activity

The presence of industry in an area means that the demand for water will be high. In industry, they need water to cool their engines, wash their products, and so on.

## 5. Quality of water supply

If the quality of water is good, the demand for water will be high as compared to low-quality water.

## 6. The pressure in distribution systems

The high pressure in distribution systems increases the rate of water demand. On the other hand, low pressure in distribution systems decreases the rate of water demand.

## 7. Development of sewage facility

The presence of sewage or sanitary systems increases the rate of water demands and vice-versa. In this case, more water is required to use Bathtub, Shower, Bidet, etc.

## 8. System of supply

If water comes to the consumers for 24 hours, then the use of water will increase, hence, the rate of water demand will be high. On the other hand, if water is served only for a fixed time, it may be once or twice a day, then the use of water will reduce, hence, the rate of water demand will be low.

## 9. Cost of water

Water price is also an important factor that affects the rate of water demand. If the cost is increased, the water demand will decrease and vice versa. If the price of water is high, the wastage of water will be less because consumers will try to reduce unwanted usage of water so that they have to pay less money.

## 10. Policy of metering

The policy of metering also affects the rate of water demand. Installing meters in consumer houses decreases the rate of water demand, On the other hand, if there is no meter, the demand for water increases. But, sometimes, some policies are imposed on the consumers, like – the price of per liter water will be the same for all consumers for a certain limit(take an example: 20 liters per day per head), but after crossing their daily limit (if the consumer uses more than 20 liters), the price of per litter water will be more. This type of policy helps to decrease the rate of water demand.

## 11. Living Standards

The rate of water demand also depends on the consumer’s economic status. Rich consumers use more water as they do not think about the cost of the water. Rich families also use more home appliances( like – Washing Machine, Sprayer, Dishwasher, Car Washer, etc.) that may require more water. Meanwhile, middle-class and poor consumers use less water as they use fewer appliances and cost is another factor for them.

## Water Quantity Estimation for a City

Let’s assume a city ‘A’, the population of this city is 200k. Before designing the water supply scheme, we need to calculate the estimated water consumption.

Here, two things are needed: one is per capita demand in liters per day per head. Another is the population of the location where water is to be served.

Quantity of water = Per capita demand * population

Factors Affecting Consumptive Use of Water

Ring Water Distribution System

Grid Iron System

# Diversion Headwork – Definition, Location, Function & Component

## What is the Diversion Headwork?

The hydraulic structure which is constructed at the head of the canal, so as to ensure a regulated continuous supply of silt-free water with a certain minimum head into the canal is known as diversion headwork.

### Components Of a Diversion Headwork

1. Weir or barrage
2. Under sluices
3. Divide wall
6. Silt excluders
7. River training works

The location of diversion headwork depends on the stages of flow in the river. The river in our country has the following four stages:

1. Rocky stage or hilly stage
2. Boulder stage
3. Alluvial stage
4. Delta stage

1. To raise the water level at the head of the canal.

2. It regulates the supply of water into canals.

3. It controls the entry of silt into the canal.

4. It controls the fluctuation of water level in the river during different seasons.

5. It provides some storage of water for a short period.

### Site Selection For Diversion Headwork

1. The river section at the site should be narrow and well-defined.

2. The elevation of the site should be higher than the area to be irrigated for gravity flow.

3. The site should be such that the wire and barrage can be aligned at right angles to the direction of flow in the river.

4. The diversion headworks should not submerge. Valuable land and property on its upstream site.

5. The site should provide a good foundation for the construction of weir and barrage.

6. The required materials for construction should be available near the site.

7. The site should be easily accessible by road or rail.

8. The overall cost of the project should be minimum.