MR

Lecture 4-Highway Classification.ppt

Highway Classification

Functions of Roads

  • Mobility: Primarily provided by arterial roads, these roads are designed to facilitate the flow of traffic over long distances, allowing for higher speed travel typical of urban and suburban areas.

  • Access: Local roads serve the purpose of providing direct access to properties, homes, and businesses. They typically have lower speed limitations to ensure safety in residential areas.

  • Both: Collector roads balance between mobility and access, gathering traffic from local roads while still connecting to higher-speed arterial roads.

Reasons for Road Classification

  • Classification of roads is crucial as it determines the government’s responsibility for maintenance and funding, ensuring that appropriate resources are allocated for road upkeep.

  • It influences the design and construction practices employed, ensuring roads meet specific safety and functionality standards.

  • Additionally, it affects funding sources, particularly in terms of Federal-Aid, where different classes of roads may qualify for specific federal funding opportunities.

Classification of Highways

The National Highway Act of 1956 provides essential criteria for classification based on various factors:

  • Based on Weather:

    • All Weather Roads: Designed to remain usable in all weather conditions.

    • Fair Weather Roads: Suitable for use primarily in favorable weather conditions.

  • Based on Type of Carriageway:

    • Paved Roads: Typically asphalt or concrete roads designed for higher durability and speed.

    • Unpaved Roads: Often include gravel or dirt roads, suitable for lower traffic volumes.

  • Based on Pavement Surface:

    • Surfaced Roads: Have a constructed surface, designed to provide a smooth driving experience.

    • Un-surfaced Roads: Natural pathways without a constructed surface, potentially causing increased wear on vehicles.

Traffic Volume Classifications

  • Traffic Volume: Classified as Heavy, Medium, or Light traffic, with each category influencing design characteristics and maintenance requirements.

  • Load/Tonnage Classifications: Defined as Class 1/2, or Class A/B based on tonnes of traffic per day, impacting road strengthening requirements and funding.

  • Location-Based Classification:

    • NH: National Highway, critical for inter-state and national traffic.

    • PH: Provisional Highway, temporary usage until fully classified.

    • MDR: Major District Road, connecting larger communities within districts.

    • ODR: Other District Road, local roads serving lesser traffic needs.

    • Farm to Market: Specifically addresses rural roadways facilitating agricultural production access to marketplaces.

Modified Highway Classification System

Includes distinctions for:

  • Primary Highways:

    • Motorways: High-speed roads with controlled access designed for long-distance travel.

    • Expressways: Similar to motorways, but may allow limited access points and some types of traffic.

    • National Highways: Form essential parts of the national transportation framework.

  • Secondary Highways:

    • Provincial Highways: Serve as arterial routes linking key urban and rural centers within a province.

    • Major District Roads: Foster connections among important economic zones within districts.

  • Tertiary Highways:

    • ODR (Other District Roads) and Rural Roads: Primarily serve local traffic and farms.

Highway Functional Classification Concepts

  • Functional classifications act as guiding frameworks with specific state variations based on geography.

  • Flexibility exists as boundaries for functional classes are not rigid, allowing for adjustments as per state and regional needs. Reference practices made by FHWA functional classification framework.

Urban Road Classification

  • Arterial Roads: High-capacity primary roads that facilitate long-distance travel.

  • Sub-Arterial Roads: Secondary roads with moderate traffic volumes, often connecting urban and suburban areas.

  • Collector Roads: Gather local traffic from residential areas and funnel it to arterial roads, typically with permissible on-street parking.

  • Local Streets: Primary access routes for residential areas, designed to cater traffic at lower speeds.

  • Cul-de-Sac: A type of local street characterized by a dead end, enhancing neighborhood safety.

  • Pathway: Designed primarily for non-motorized transport such as pedestrians and cyclists.

  • Driveway: Private access routes leading to individual properties.

Urban Connection Strategies

  • Focus on grouping population centers strategically and ensuring seamless connectivity with major traffic points and reducing congestion.

  • Emphasis on integrating networks and considering road spacing as part of comprehensive urban planning approaches.

Urban Boundaries and Considerations

  • Urban Clusters: Defined by specific population density metrics used to plan infrastructure.

  • Urban Places: Established based on political and administrative boundaries, impacting resource allocation and service delivery.

  • Adjustments to urban plans are made based on evolving needs and growth projections.

Design Considerations for Roads

  • Geometric design policy is chiefly guided by AASHTO (2001) emphasizing the importance of geometry in safety and functionality.

  • Roads focus on mobility, while local streets center around providing access to residences and businesses.

Design Features

Key focus areas include:

  • Speed: Maintaining appropriate design speeds for different road types.

  • Levels of Service: Ensuring road designs accommodate projected traffic volumes.

  • Alignment: Designing roads for safe maneuverability and efficiency.

  • Road Width: Adequately provide for varying traffic conditions and classifications.

  • Clearances: Ensure compliance with safety standards.

  • Grades: Design roads accounting for topographical challenges.

Federal-Aid Systems

  • National Highway System: Includes principal arterials vital for national transportation.

  • Surface Transportation Program: Supports the development and maintenance of urban and rural roadway networks.

Urban Features Enhancements

Key aspects that enhance the functionality and safety of urban roads include:

  • Parking facilities

  • Adequate lighting

  • Proper gutter treatments

  • Sidewalks for pedestrian safety

  • Utilities infrastructure

Access Control Types

  • Full Control: Characteristic of expressways and freeways, allowing high-speed travel with no interruptions.

  • Partial Control: Involves managed access through medians and limited controlled intersections.

Access Control Methods

Strategies include:

  • Implementing land-use ordinances to guide developments near roads.

  • Utilizing geometric designs, including medians to enhance safety and flow.

  • Differentiating between direct and indirect access to facilitate movement.

Relationship to Service in Road Systems

The distinction between mobility and land access is vividly illustrated through classified road systems:

  • Arterials: Focus on high mobility with generally low access points.

  • Collectors: Strike a balance between mobility and access, facilitating movement while providing connections.

  • Locals: Designed to maximize access, providing extensive connectivity to properties while allowing lower mobility.

Specific Road Class Features

  • Arterial Roads: Characterized by no frontage access or parking, with design speeds around 80 km/hr and land widths of approximately 50-60m.

  • Sub-Arterial Roads: Design speeds of 60 km/hr, spacing dependent on urban density.

  • Collector Streets: Design speed of 50 km/hr, allowing full access and parking capability.

  • Local Streets: Slower design speed of 30 km/hr, acting as primary access avenues to properties.

  • CUL–DE–SAC Roads: Recommended with a single entry and exit point, enhancing residential area connectivity and safety.

Functional Classification Information

A comprehensive overview of traffic mobility and land access balance is established through functional classification methods. Breakdown of highway functional classes by mileage:

  • Highway Functional Classes (Urban Miles):

    • Principal Arterials: 76,033 miles (9%)

    • Minor Arterials: 90,475 miles (10%)

    • Collectors: 89,310 miles (10%)

    • Local Roads: 628,369 miles (71%)

  • Highway Functional Classes (Rural Miles):

    • Principal Arterials: 132,451 miles (4%)

    • Minor Arterials: 137,875 miles (4%)

    • Major Collectors: 434,090 miles (14%)

    • Minor Collectors: 272,047 miles (9%)

    • Local Roads: 2,096,837 miles (68%)

Road Patterns in Urban Planning

Various road patterns, including rectangular, radial, and hexagonal layouts, contribute to the overall efficiency of navigation and accessibility within urban environments, facilitating smoother traffic flows and enhancing connectivity.