Dimensions and Weights of Road Design Vehicles

The Introduction of IRC 3 defines key vehicle terms and axle configurations essential for road design. Notably, a tandem axle consists of two or more consecutive axles spaced between 1.2 m and 2.5 m apart, sharing load equally (Clause 1.2 and 3.9). Definitions include truck-tractor (a vehicle designed to draw others without carrying trailer load), truck-trailer combination, and overall vehicle width excluding safety devices and tyre bulge (Clauses 3.12, 3.13, 3.14). Vehicle type notation uses digits and letters to indicate axle numbers and trailer types, e.g., '2-S2' means a two-axle truck-tractor with a tandem-axle semi-trailer (Clause 4). These definitions and notations form the basis for specifying dimensions and weights of road design vehicles, which are detailed in subsequent sections.

Sources: Clause 1.2, Clause 3.9, Clause 3.12, Clause 3.13, Clause 3.14, Clause 4

The scope of IRC 3 focuses on establishing the basis for designing road components considering the maximum dimensions and weights of design vehicles. As per the context, all road components, whether new or improved, must be designed to accommodate vehicles conforming to this Standard, ensuring initial adequacy or future upgradability. Key vehicle parameters influencing design include:

• Width: Influences traffic lane and shoulder widths.
• Height: Determines clearance for under-bridges, overhead lines, and structures.
• Overall Length: Affects horizontal and vertical curve design and safety regulations for passing/overtaking.
• Axle Load: Governs pavement thickness design.
• Total Weight: Controls limiting gradients.

These parameters are critical for the design of road elements to ensure safety and functionality under the severest vehicle dimensions and weights specified in the Standard.

Sources: Clause None (Scope and Introduction)

Key definitions and vehicle types per IRC 3 include:

• Tandem Axle Weight (Clause 3.9): Total weight on two or more consecutive axles spaced between 1.2 m and 2.5 m apart.
• Trailer: Vehicle drawn by a motor vehicle, carrying no part of its own weight on the towing vehicle.
• Truck: Motor vehicle primarily for transporting goods.
• Truck-Tractor (Clause 3.12): Vehicle designed to draw others, carrying only part of the load weight.
• Truck-Trailer Combination (Clause 3.13): Truck or tractive unit with a trailer.
• Width Overall (Clause 3.14): Total outside transverse dimension including load but excluding safety devices and tyre bulge.

Vehicle Type Notation (Clause 4):

• First digit = number of axles on truck/tractor.
• 'S' = semi-trailer; digit after 'S' = semi-trailer axles.
• Other digits = trailer axles.

Examples:

• 2-S2 = two-axle truck-tractor + tandem-axle semi-trailer.
• 2-2 = two-axle truck + two-axle trailer.

These definitions and notations form the basis for road design dimensions and weights affecting lane width, clearances, curves, and pavement thickness.

Sources: Clause 1.2, Clause 3.9, Clause 3.12, Clause 3.13, Clause 3.14, Clause 4

As per IRC 3 Clause 4, the notation for vehicle types uses digits and letters to represent axle counts and vehicle configurations:

• The first digit indicates the number of axles on the truck or truck-tractor.
• The letter "S" denotes a semi-trailer.
• The digit immediately following "S" indicates the number of axles on the semi-trailer.
• Any digit not preceded by "S" (other than the first digit) indicates the number of axles on a trailer.

Examples:

• 2-S2: A two-axle truck-tractor with a tandem-axle semi-trailer.
• 2-2: A two-axle truck with a two-axle trailer.

This notation helps classify vehicle types for design and load considerations on roads.

Additional definitions from Clause 3 include:

• Tandem Axle Weight: Weight on two or more consecutive axles spaced 1.2 m to 2.5 m apart.
• Truck-Tractor: Vehicle designed to draw others, carrying no load except part of the drawn vehicle's weight.

These notations and definitions are essential for interpreting vehicle configurations in road design standards.

Sources: Clause 1.2, Clause 3.9, Clause 3.12, Clause 3.13, Clause 3.14, Clause 4

The key parameters for road design vehicles as per IRC 3 include dimensions and weights that influence various road components. Specifically:

• Width: Determines the width of traffic lanes and shoulders.
• Height: Influences clearance requirements for under-bridges, electrical lines, and overhead structures.
• Overall Length: Important for designing horizontal and vertical curves and safety regulations for passing/overtaking.
• Axle Load: Governs pavement thickness design.
• Total Weight: Controls limiting gradients on roads.

These parameters form the basis for designing road elements to accommodate vehicle dimensions and weights safely and efficiently. The standard emphasizes these factors but does not provide explicit numeric tables or formulas in the retrieved context.

Sources: Clause 1.1

The maximum permissible weights for transport vehicles as per IRC 3 are governed by axle and gross weight limits. Tandem axles spaced between 1.2 m and 2.5 m shall not exceed 18 tonnes (Clause 1.2). The maximum permissible gross weight is the sum of individual single and tandem axle weights (Clause 6.3). The key table below summarizes maximum gross and axle weights for various vehicle types:

Where FAW = Front Axle Weight, RAW = Rear Axle Weight, TA = Tandem Axle with 8 tyres (Clause 6.3). Road components must be designed for the severest applicable dimensions and weights to ensure adequacy (no specific clause number).

Sources: Clause 1.2, Clause 6.3, Table: Maximum Permissible Gross Weights and Maximum Axle Weights of Transport Vehicles

The key axle weight limits per IRC 3 are as follows:

• Single axle with dual wheels: Maximum gross weight is 10.2 tonnes.
• Single axle with single wheels: Maximum gross weight is 6 tonnes (Clause 10.2).
• Tandem axles: Two or more consecutive axles spaced between 1.2 m and 2.5 m apart, with a combined maximum weight of 18 tonnes (Clause 1.2 and 6.2).

The maximum permissible gross weight for vehicles is the sum of individual axle weights. The table below summarizes typical vehicle types and their axle weight limits (tonnes):

Notes:

• FAW = Front Axle Weight
• RAW = Rear Axle Weight
• TA = Tandem Axle fitted with 8 tyres

These limits ensure compliance with road design and vehicle safety (Clauses 1.2, 6.2, 6.3, 10.2).

Sources: Clause 1.2, Clause 6.2, Clause 6.3, Clause 10.2, Table 6.3

As per IRC 3, the key specification for tandem axle weight is that the total gross weight imposed by two axles in tandem, spaced not less than 1.2 m and not more than 2.5 m apart, shall not exceed 18 tonnes (Clause 1.2 and 6.2). Tandem axle weight refers to the total weight transmitted to the road by two or more consecutive axles within this spacing (Clause 3.9). The maximum permissible gross weight of vehicles is the sum of individual single axle and tandem axle weights (Clause 6.3). For example, a tandem axle fitted with 8 tyres (TA) can carry up to 18 tonnes, while single axles with dual wheels are limited to 10.2 tonnes and single wheels to 6 tonnes (Clause 10.2). The following table summarizes maximum permissible gross and axle weights for various vehicle types:

Sources: Clause 1.2, Clause 3.8, Clause 3.9, Clause 6.2, Clause 6.3, Clause 10.2

Key vehicle length restrictions per IRC 3 for road design are as follows:

• Single unit truck (2+ axles): Maximum overall length 11 m (excluding bumpers).
• Single unit bus (2+ axles): Maximum overall length 12 m (excluding bumpers).
• Truck-tractor semi-trailer combination: Maximum overall length 16 m (excluding bumpers).
• Truck-trailer combination: Maximum overall length 18 m (excluding bumpers).
• Vehicle combinations: Shall not comprise more than two vehicles.

These limits are specified in Clauses 5.3.1 to 5.3.5. Additionally, vehicle height limits are 3.8 m normally, 4.2 m for ISO series 1 freight containers, and up to 4.75 m for double-decker buses (Clause 3.8). These dimensions guide road component design such as lane width, clearances, and curve geometry (Clause 1.1).

Sources: Clause 3.8, Clauses 5.3.1, 5.3.2, 5.3.3, 5.3.4, 5.3.5, Clause 1.1

According to IRC 3, the key vehicle width and height restrictions for road design are as follows: The maximum vehicle height is generally limited to 3.8 m, except for double-decker buses which may be up to 4.75 m high, and vehicles carrying ISO series 1 freight containers which may be up to 4.2 m high (Clause 3.8). The vehicle width, termed as 'Width Overall', includes the total outside transverse dimension including load but excludes safety devices and tyre bulge (Clause 3.14). Maximum overall lengths are specified as: single unit trucks (≥2 axles) - 11 m, single unit buses (≥2 axles) - 12 m, truck-tractor semi-trailer combinations - 16 m, and truck-trailer combinations - 18 m (Clauses 5.3.1 to 5.3.4). No vehicle combination shall have more than two vehicles (Clause 5.3.5). These dimensions influence lane widths, clearances under bridges, and curve designs.

Sources: Clause 3.8, Clause 3.14, Clauses 5.3.1 to 5.3.5

The key criteria for selecting design vehicles per IRC 3 focus on their dimensions and weights, which influence various road design elements. Specifically:

• Width affects traffic lane and shoulder widths.
• Height determines clearance for under-bridges, overhead lines, and structures.
• Overall length (including trailers) is critical for designing horizontal and vertical curves and safety regulations for passing/overtaking.
• Axle load governs pavement thickness design.
• Total vehicle weight controls limiting gradients.

These parameters form the basis for designing road components to ensure safety and functionality, as outlined in the introductory clauses of IRC 3. Exact numerical values or tables for these dimensions and weights are not provided in the retrieved context but are fundamental to the standard's design approach.

Sources: Clause None: DIMENSIONS AND WEIGHTS OF ROAD DESIGN VEHICLES, Clause None: 1.1

The impact of vehicle dimensions and weights on road design elements per IRC 3 is summarized as follows:

• Width of design vehicle influences the width of traffic lanes and shoulders.
• Height of vehicle determines clearance requirements for under-bridges, electrical lines, and overhead structures.
• Overall length (including trailers) affects the design of horizontal and vertical curves and safety regulations for passing/overtaking.
• Axle load governs pavement thickness design.
• Total vehicle weight controls limiting gradients.

Design must consider the maximum dimensions and weights that have the severest effect on any road component. New or improved road elements should be initially adequate or upgradable to accommodate vehicles conforming to this standard (IRC 3, Clauses 1.1 and 2.1).

Sources: Clause 1.1, Clause 2.1

Key aspects of Load Distribution and Pavement Design per IRC 3 focus on vehicle dimensions and axle loads, which directly influence pavement thickness and structural design. The axle load governs pavement thickness, while total vehicle weight affects limiting gradients. Tandem axles are defined as two or more consecutive axles spaced between 1.2 m and 2.5 m apart, with their combined weight (tandem axle weight) considered for load distribution. Vehicle types are classified by axle count and trailer configuration, impacting load application on pavements. For example, a 2-S2 vehicle is a two-axle truck-tractor with a tandem-axle semi-trailer. These definitions and classifications are essential for calculating load effects on pavement layers and designing appropriate thickness to withstand stresses. Although specific formulas and tables for pavement thickness design are not provided in the retrieved context, the emphasis is on axle load and vehicle configuration as primary inputs for design.

Sources: Clause 1.1, Clause 1.2, Clause 3.9, Clause 3.12, Clause 3.13, Clause 3.14, Clause 4

The IRC 3 standard emphasizes that safety considerations for passing and overtaking are closely linked to the dimensions and weights of road design vehicles, which influence road design elements such as lane width, shoulder width, and curve geometry. Key factors include:

• Overall Length: Critical for designing horizontal and vertical curves to ensure safe passing and overtaking distances.
• Width Overall: Influences lane width and shoulder design to accommodate vehicle clearance during overtaking.
• Axle Load and Total Weight: Affect pavement thickness and limiting gradients, impacting vehicle maneuverability and safety during passing.

Vehicle types are denoted by axle numbers and trailer configurations (e.g., 2-S2 for a two-axle truck-tractor with a tandem-axle semi-trailer), which helps in understanding vehicle behavior during overtaking.

While explicit formulas for passing safety are not provided in the retrieved context, the standard underlines that vehicle dimensions and weights are cardinal in framing safety regulations for passing and overtaking (Clause 1.1).

Sources: Clause 1.1, Clause 3.9, Clause 3.14, Clause 4

The key specifications and definitions related to road design vehicles per IRC 3 include:

• Tandem Axle Weight (Clause 3.9): Total weight on two or more consecutive axles spaced between 1.2 m and 2.5 m apart, measured between parallel vertical planes across the vehicle width.

• Vehicle Types (Clause 4): Notations use digits and letters to indicate axle numbers and trailer types, e.g., '2-S2' means a two-axle truck-tractor with a tandem-axle semi-trailer.

• Width Overall (Clause 3.14): Total outside transverse dimension including load and devices but excluding safety devices and tyre bulge.

• Definitions: Truck-Tractor (Clause 3.12), Truck-Trailer Combination (Clause 3.13), and articulated axles (Clause 1.2).

These clauses form the basis for vehicle dimension and weight considerations in road design as per IRC 3.

Sources: Clause 1.2, Clause 3.9, Clause 3.12, Clause 3.13, Clause 3.14, Clause 4