Road Design Standards Quiz

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Questions and Answers

What is the width of a two-lane road with raised curbs?

5.5 m

7.0 m

3.75 m

7.5 m (correct)

What is a primary function of medians on roads?

To provide additional parking space

To increase the speed of vehicles

To reduce head-on collisions (correct)

To support utility poles

Which type of median is primarily designed to separate opposing traffic lanes and improve safety?

Painted median

Flushed median

Depressed median

Raised median (correct)

What is a characteristic function of depressed medians?

To manage water runoff Signup and view all the answers

What materials are commonly used to construct median safety barriers?

Concrete, steel, or wire rope Signup and view all the answers

How wide is a standard single lane road?

3.75 m Signup and view all the answers

What is NOT a feature of flushed medians?

Lowers traffic speed Signup and view all the answers

Which type of road margin primarily serves practical functions such as managing utilities?

Depressed margins Signup and view all the answers

What is the primary function of a lay bye?

To provide a space for vehicles to stop without blocking traffic. Signup and view all the answers

Which type of kerb is designed to help vehicles climb easily?

Low or Mountable type Kerb. Signup and view all the answers

What is the minimum camber of a shoulder compared to the cross slope of adjoining pavement?

0.5% steeper than the cross slope. Signup and view all the answers

What is the primary objective of providing camber on a pavement?

To drain rainwater quickly from the road surface. Signup and view all the answers

What is a common disadvantage of excessive camber?

Formation of cross ruts or depressions. Signup and view all the answers

Which type of kerb is most appropriate for areas with high pedestrian traffic?

Semi-Barrier type Kerb. Signup and view all the answers

What shape of camber is preferred for fast-moving vehicles during overtaking operations?

Parabolic or elliptic shape. Signup and view all the answers

Which of the following is NOT a function of kerbs?

To provide additional parking space. Signup and view all the answers

What is the camber percentage range for high type bituminous surfacing or cement concrete?

1.7 to 2.0% Signup and view all the answers

What is the primary purpose of the Road Cross Section in highway engineering?

To represent the highway's vertical slice and arrangement of components Signup and view all the answers

Which surface type has the highest camber percentage range?

Earth Signup and view all the answers

Which layer of road pavement is in direct contact with vehicle wheels?

Surface/Wearing Course Signup and view all the answers

What is a key function of effective drainage in road maintenance?

To prevent water-related issues such as flooding Signup and view all the answers

What are table drains primarily used for?

To allow water to drain away from the road and pavement surface Signup and view all the answers

What characterizes the Base Course in road pavement layers?

It is immediately under the wearing surface and must be of high quality Signup and view all the answers

Which drainage system is more appropriate for conditions where water may drain down an embankment onto the road surface?

Catch drains Signup and view all the answers

What is the primary function of the Sub Grade layer?

To support the road pavement and is considered to have infinite thickness Signup and view all the answers

Which component of the road cross section is primarily for travel and may consist of multiple lanes?

Carriageway or Traffic Lanes Signup and view all the answers

What is the camber percentage range for thin bituminous surfacing?

2.0 to 2.5% Signup and view all the answers

Which type of drainage is considered a basic form and is generally unsealed?

Table drains Signup and view all the answers

Why are wider traffic lanes generally considered safer?

They permit larger vehicles to pass without moving sideways Signup and view all the answers

What type of material is typically used for the Sub Base layer in road construction?

Natural gravel or granular material Signup and view all the answers

What potential issues can effective drainage prevent on roadways?

Flooding and erosion Signup and view all the answers

Which statement best describes the preparation of the Sub Grade layer?

It is typically the top 12 inches of naturally occurring material Signup and view all the answers

What is one of the primary functions of shoulders on a road?

To support pavement laterally Signup and view all the answers

What is the preferred characteristic of the shoulder color in relation to the pavement?

It should be distinct from the pavement color Signup and view all the answers

What is a key purpose of a lay bye along the road?

To provide a stopping area clear of the roadway Signup and view all the answers

What must a driveway connecting highways to commercial establishments primarily ensure?

Distance from intersections Signup and view all the answers

Which type of track is specifically designed for high volumes of bicycle traffic in urban areas?

Cycle Track Signup and view all the answers

What is one function of guard rails on a road?

Stop vehicles from running off embankments Signup and view all the answers

What is a recommended dimension for a standard lay bye?

3.0 m width and 30 m length Signup and view all the answers

What characteristic should the surface of shoulders have compared to traffic lanes?

Rougher to discourage regular use as lanes Signup and view all the answers

Study Notes

Road Design and Components

Different types of roads have designated widths to ensure safety and efficiency, varying from single lanes (3.75 m) to multi-lane pavements (3.5 m per lane).
A divided highway features a median that separates opposing traffic, which serves to prevent head-on collisions, reduce glare from headlights, and provide refuge for cross-traffic at intersections.

Types of Medians

Raised Medians offer physical separation for safety and improved aesthetics through landscaping, commonly used on high-traffic roads.
Depressed Medians are below road level, assisting with water runoff and utility placement, primarily in urban areas.
Flushed Medians are marked by painted lines, serving as waiting areas for turning vehicles, frequently seen in urban settings.
Median Safety Barriers are constructed to absorb or redirect impacts, preventing crossovers in traffic.

Road Cross Section

Road cross sections illustrate the vertical arrangement of the road components, crucial for construction and functional understanding.

Pavement Layers

Surface/Wearing Course: The top layer in direct contact with vehicles, made from bitumen-based materials.
Base Course: Positioned under the surface, it must be of high quality to withstand severe load.
Sub Base: A granular layer above the subgrade, often natural gravel.
Sub Grade: The foundational layer consisting of existing natural soil or fill material.

Carriageway and Safety Features

The carriageway is designed for vehicle travel, ideally wider for safety, allowing large vehicles to pass comfortably.
Shoulders provide support for the pavement, emergency stopping areas, and pedestrian/bicycle use, designed to withstand heavy loads.
Kerbs support footpaths and medians, categorized into low, semi-barrier, and barrier types based on height and function, facilitating drainage and delineating pavement edges.

Camber and Cross Slope

Camber is the transverse slope for draining rainwater, important for quick pavement drying and safety; it varies based on surface type and rainfall.
Excessive camber can cause vehicle discomfort and structural issues like transverse tilting or ruts.

Drainage Systems

Effective drainage prevents flooding, erosion, and road damage, vital for road longevity and safety.
Table Drains are located beside the road for basic water drainage, while Catch Drains direct potential runoff during cuts, essential for maintaining roadway integrity.

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Description

Test your knowledge on the standards and classifications of road widths. This quiz covers various categories, including single lane, multi-lane, and carriageway specifications. Understand the requirements for different road types in civil engineering.