Module-3.pdf

MODULE 3 DESIGN CRITERIA FOR HIGHWAYS AND RAILWAYS  DESIGN CRITERIA FOR HIGHWAYS Highway design involves the planning, geometric design, and construction of roads that ensure safety, efficiency, and comfort for road users. The design criteria are influenced by factors such as expected tr...

MODULE 3 DESIGN CRITERIA FOR HIGHWAYS AND RAILWAYS  DESIGN CRITERIA FOR HIGHWAYS Highway design involves the planning, geometric design, and construction of roads that ensure safety, efficiency, and comfort for road users. The design criteria are influenced by factors such as expected traffic volumes, environmental conditions, and the type of vehicles using the road.  Key Design Criteria for Highways 1.Design Speed: The maximum safe speed that can be maintained over a specific segment of the highway under ideal conditions. It influences the geometric features like curve radii, sight distances, and gradient. 2.Lane Width: Standard lane widths are typically 3.6 meters (12 feet) for highways, though this can vary based on traffic conditions and vehicle types. 3.Shoulder Width: The shoulder provides space for stopped vehicles and emergency use. Widths typically range from 2.4 to 3.0 meters (8 to 10 feet). 4. Sight Distance: The distance a driver can see ahead, which must be sufficient to stop or make decisions. It is crucial for safety, especially on curves and at intersections.  Key Design Criteria for Highways 5. Horizontal and Vertical Alignment: The layout of the highway in the horizontal plane (curves, tangents) and vertical plane (grades, slopes) is designed to ensure smooth traffic flow and safety. 6. Pavement Design: Involves the selection of materials and thickness for the pavement layers to withstand traffic loads and environmental conditions over time. 7. Intersection Design: The layout and control of intersections are crucial for safety. This includes considerations for turning lanes, signalization, and pedestrian crossings.  Design Criteria for Railways Railway design focuses on the efficient and safe movement of trains, considering factors like speed, load, track alignment, and environmental impacts.  Key Design Criteria for Railways 1.Track Gauge: The distance between the inner faces of the rails. Standard gauge is 1,435 mm (4 ft 8 1⁄2 in), but other gauges are used in different regions and for different types of railways. 2.Gradient and Alignment: Vertical and horizontal alignment of tracks must ensure smooth operation and safety, especially at high speeds. Gradients are typically kept low to minimize strain on locomotives. 3.Curve Radius: Larger radii are required for high-speed rail to minimize centrifugal forces and ensure passenger comfort. Minimum radii depend on train speed and track design. 4.Track Structure: The design of the track bed, including rails, sleepers (ties), and ballast, is critical for supporting train loads and ensuring track stability.  Key Design Criteria for Railways 5. Signaling and Control Systems: Modern railways rely on advanced signaling and control systems to manage train movements, ensure safety, and optimize traffic flow. 6. Environmental Impact: Railway design must consider environmental impacts, including noise pollution, land use, and effects on local ecosystems. 7. Station Design: Stations must be designed for efficient passenger flow, accessibility, and integration with other modes of transport.  References AASHTO. (2018). A Policy on Geometric Design of Highways and Streets. American Association of State Highway and Transportation Officials. Retrieved from AASHTO. FHWA. (2019). Pavement Design Guide. Federal Highway Administration. Retrieved from FHWA. AREMA. (2018). Manual for Railway Engineering. American Railway Engineering and Maintenance-of-Way Association. Retrieved from AREMA. UIC. (2016). Railway Track Design. International Union of Railways. Retrieved from UIC. ERA. (2017). ERTMS: European Rail Traffic Management System. European Railway Agency. Retrieved from ERA.  References EEA. (2019). Railway Environmental Impact Assessment. European Environment Agency. Retrieved from EEA. ITE. (2020). Intersection Design Handbook. Institute of Transportation Engineers. Retrieved from ITE.