As per IRC, which of the following is NOT a recommended characteristic of the road shoulder?
It’s minimum width should be 4.6 m.
Understanding IRC Recommendations for Road Shoulder Characteristics
Road shoulders are an important part of highway design. They provide space for disabled vehicles, improve visibility, allow for maintenance operations, and enhance overall road safety. The Indian Road Congress (IRC) provides detailed guidelines on the characteristics and dimensions of road components, including shoulders.
The question asks us to identify which of the given options is NOT a recommended characteristic of a road shoulder as per IRC guidelines. Let's examine each option:
Analysis of Road Shoulder Characteristics
-
Option 1: Its surface must be rough as compared to the adjacent road.
This is a recommended characteristic. A rougher surface texture on the shoulder compared to the main carriageway helps to provide a tactile and audible warning to drivers who might drift off the road. It also provides better traction in case a vehicle needs to pull over onto the shoulder, especially in wet conditions.
-
Option 2: Its minimum width should be 4.6 m.
This statement is NOT typically a recommended minimum width for a road shoulder according to IRC standards. Recommended minimum widths vary based on the type of road (e.g., National Highway, State Highway, Major District Road) and the speed of traffic. For high-speed highways, IRC guidelines often recommend a minimum shoulder width around 2.5 to 3.0 meters. A minimum width of 4.6 meters would be exceptionally wide and is not a standard minimum requirement across the board for all road types in India.
-
Option 3: It must be able to support a truck load in wet weather.
This is a recommended characteristic. The shoulder must be structurally sound and adequately constructed to support the occasional load of a heavy vehicle, such as a truck, that might need to stop or park on it. This structural integrity is required even in wet weather conditions when the subgrade strength might be reduced.
-
Option 4: Its colour must be different from that of the road.
This is a recommended characteristic for visual delineation. A different colour or surface treatment helps drivers easily distinguish between the main carriageway and the shoulder, especially at night or during poor visibility conditions. This clear visual boundary enhances safety by guiding drivers and preventing accidental encroachment onto the shoulder.
Conclusion on Road Shoulder Recommendations
Based on the analysis of each characteristic against typical IRC recommendations:
- Rough surface: Recommended
- Ability to support truck load in wet weather: Recommended
- Different colour/texture: Recommended
- Minimum width of 4.6 m: NOT a standard recommended minimum width
Therefore, the characteristic that is NOT a recommended characteristic of the road shoulder as per IRC is that its minimum width should be 4.6 m.
Key IRC Guidelines for Road Shoulders
| Characteristic | IRC Recommendation (General) |
|---|---|
| Surface Texture | Rougher than carriageway |
| Structural Strength | Adequate to support occasional heavy vehicles (e.g., trucks) |
| Visibility | Visually distinct from carriageway (e.g., different colour/material) |
| Minimum Width | Varies based on road type; commonly 2.5 m to 3.0 m for major highways, not typically 4.6 m minimum. |
Revision Table: IRC Road Design Elements
| Element | Purpose | Key Design Considerations (IRC) |
|---|---|---|
| Carriageway | Main traffic lane(s) | Width (lane width), number of lanes, cross slope, pavement type |
| Shoulder | Support for disabled vehicles, safety zone, drainage | Width, surface type, structural strength, delineation |
| Median | Separates opposing traffic flows | Width, type (raised, depressed, barrier), vegetation |
| Right of Way (ROW) | Total land acquired for the road | Width needed for current and future expansion, services |
Additional Information: Importance of Road Shoulder Design
Proper design and construction of road shoulders are crucial for the overall safety and efficiency of a highway. Some key aspects include:
- Emergency Stops: Shoulders provide a safe area for vehicles to stop in case of mechanical breakdown, flat tire, or other emergencies, keeping the main traffic lanes clear.
- Safety Buffer: They act as a safety buffer, providing recovery space for drivers who momentarily lose control or drift off the road.
- Drainage: Shoulders help manage surface water runoff from the carriageway, preventing water from accumulating on the road surface and potentially causing hydroplaning or pavement damage.
- Structural Support: They provide lateral support to the pavement structure of the main carriageway, contributing to its long-term durability.
- Maintenance: Shoulders can be used by maintenance vehicles, reducing disruption to traffic flow.
IRC standards aim to ensure that road shoulders fulfill these functions effectively and safely, contributing to the overall quality and safety of the road network.
Important Questions from Highway Geometric Design
Calculate the design rate of super elevation (%) on a highway in a plain terrain, if design speed of the highway is 80 kmph and radius of the curve is 400m.
Which of the following is the main function of “submerged” kerbs in rural roads?
Which of the following statements are correct, with reference to the Road Formation width?
i. It is the bottom width of the embankment.
ii. It is the bottom width of the cutting.
iii. It is inclusive of the width of the shoulders.
iv. It is inclusive of the width of side drains.
Which of the following gradients will have the maximum value?
Find the length of vertical curve connecting two grades + 0.4% and – 0.3%, where the rate of change of grades is 0.1% per 30 m at summit.
