MR

Lecture 4-Highway Classification.ppt

Highway Classification

Overview

Understanding how roads are classified is essential for managing highways, ensuring efficient transportation, and ensuring adequate maintenance. Proper classification not only facilitates better decision-making regarding infrastructure development but also optimizes the flow of traffic and enhances overall roadway safety.

Function of Roads

  • Provide Mobility:

    • Arterial Roads: Major routes designed for high-volume traffic flows that link urban areas to each other and to rural areas, providing efficient transportation for long-distance travel.

  • Provide Access:

    • Local Roads: Smaller roads that cater specifically to local needs, providing access to residential areas, local businesses, and connecting to higher-class roads.

  • Provide Both:

    • Collector Roads: Intermediate roads that balance the dual objectives of mobility and access, facilitating the transition of traffic from local streets to arterial roads.

Reasons for Classifying Roads

  • Determines Responsibilities: Helps establish clear responsibility among various government levels, assisting in administrative planning and resource allocation.

  • Influences Design Standards: Road classification influences the engineering standards and design specifications necessary for road construction, impacting long-term durability and safety.

  • Affects Funding: The classification impacts budget allocations, determining where financial resources are distributed for road maintenance, upgrades, and new constructions.

  • Impacts Federal-Aid Eligibility: Certain classifications may qualify for federal aid, ensuring that critical infrastructure receives necessary support for improvements.

Classification of Highways

Based on Weather Conditions

  • All Weather Roads: Designed to remain accessible in diverse weather conditions, ensuring uninterrupted transportation.

  • Fair Weather Roads: These roads are only usable in favorable weather, often limiting transportation options in inclement conditions.

Based on Carriageway Type

  • Paved Roads: Feature a surface material that provides a smoother ride and better durability against wear and tear.

  • Unpaved Roads: Lack a solid surface, which can hinder travel, especially in adverse weather.

Based on Pavement Surface

  • Surfaced Roads: Have a continuous surface layer that aids in durability and overall performance.

  • Unsurfaced Roads: Do not have a uniform surface layer, often used in rural or less trafficked areas.

Traffic Volume Classification

Based on Traffic Volume

  • Heavy Traffic: Roads experiencing high levels of use require robust infrastructure capable of sustaining daily wear and tear.

  • Medium Traffic: These roads handle a standard level of road capacity, designed for moderate use without extensive demands on infrastructure.

  • Light Traffic: Characterized by low vehicle counts, often found in rural areas or less populated regions.

Based on Load or Tonnage

  • Classes: Roads may be classified (e.g., Class 1, Class 2) depending on the tonnes of loads they are designed to support per day.

Based on Location and Function

  • NH: National Highway – the backbone of the interstate transport system.

  • PH: Provisional Highway – typically under development or awaiting classification.

  • MDR: Major District Road – critical for intra-district connectivity.

  • ODR: Other District Road – complementing higher-class roads and often serving rural areas.

  • Farm to Market Roads: Specifically classify rural roads that facilitate the transportation of goods from farms to market.

Modified System of Highway Classifications

Primary

  • Motorways: Characterized by controlled access, primarily designed for high-capacity and uninterrupted traffic flow, minimizing internal disruptions.

  • Expressways: Built for high-speed travel, allowing for speeds up to 120 km/h, with full access control to enhance safety and efficiency.

  • National Highways: Major interstate routes that form critical connections between different states and regions.

Secondary

  • Provincial Highways: Arterial roads that operate within a province, linking towns and cities to national highways.

  • Major District Roads: Key connectors within districts that link significant market areas and support regional economies.

Tertiary

  • ODR: Other district roads that bridge rural connections to the wider road network.

  • Rural Roads: Essential in connecting smaller villages and providing access to higher category roads and markets.

Highway Functional Classification

Functional classification serves as guidelines that may differ by state or region, adapting as necessary to meet local needs and development pathways.

Urban Road Classification

Types of Roads

  • Arterial Roads: Major routes designed to carry large volumes of traffic efficiently.

  • Sub-Arterial Roads: Secondary routes that support arterial traffic and connect to them.

  • Collector Roads: These roads gather and distribute local traffic to and from arterial roads, balancing local accessibility with mobility.

  • Local Streets: Provide essential access to properties and facilitate low-speed traffic within neighborhoods.

  • Cul-de-Sac: Dead-end streets that offer limited access while enhancing neighborhood safety and promoting community interaction.

Urban Planning Considerations

Notable Aspects

  • Population Center Grouping: Strategic planning for population density and urban growth.

  • Integrating Networks: Designing interconnected roadway systems to enhance traffic flow and minimize congestion.

  • Adaptation to Changes: Flexibility in roadway designs to accommodate urban development and evolving transportation needs.

Design Considerations for Urban Roads

In accordance with AASHTO’s Green Book (2001), key aspects include:

  • Mobility with Controlled Access: Arterials prioritize traffic movement while limiting local access to enhance flow.

  • Access Promotion: Local roads enhance accessibility, necessitating controlled mobility to prevent congestion.

Urban Features to Consider

  • Parking: Adequate parking solutions to reduce on-street congestion.

  • Lighting: Essential for safety and security in urban areas.

  • Curbing and Guttering: Critical for effective drainage and maintaining roadway conditions during adverse weather.

  • Sidewalk and Utility Placements: Proper planning for pedestrian access and utility service placement for long-term infrastructure efficiency.

Access Control Methods

Strategies to manage access to major roadways include:

  • Land Use Ordinances: Zoning laws to guide the development of properties adjacent to roads.

  • Geometric Design: Designing roadways with features that control where and how access can occur, enhancing safety and flow.

Functional Relationship

A crucial aspect of roadway design, balancing traffic mobility and land access is essential:

  • High Mobility Focus: Arterials concentrate on traffic movement with limited accesses.

  • Balanced Role of Collectors: Designed to support both mobility and access needs, accommodating varying traffic demands.

  • Local Access Prioritization: Local roads emphasize direct access to properties as opposed to through traffic.

Specific Road Classifications

Collector Streets

Designed to efficiently gather and distribute traffic between local streets and arterials while allowing for full access, including parking allowances.

Local Streets

Critical for residential neighborhoods, characterized by low traffic speeds and frequent access points for properties.

CUL-DE-SAC

Usually found in residential settings, featuring only one entry/exit point and promoting a sense of community while minimizing through traffic.

Conclusion

In conclusion, understanding highway classifications enables better urban planning, enhances traffic management, and ensures effective transportation infrastructure capable of supporting economic growth and urban development.