1 / 22

Geometric Design: General Concept

Geometric Design: General Concept. CE331 Transportation Engineering. Objectives. Maximize Comfort Safety Economy Minimize Environmental impacts … Design a safe and efficient system that addresses community and environmental needs. Location Rural Urban Functional class

lapple
Download Presentation

Geometric Design: General Concept

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Geometric Design:General Concept CE331 Transportation Engineering

  2. Objectives • Maximize • Comfort • Safety • Economy • Minimize • Environmental impacts … Design a safe and efficient system that addresses community and environmental needs

  3. Location Rural Urban Functional class Arterial (Principal and Minor Collector (Major and Minor) Local Designation Interstate Federal State County Local Highway Classification

  4. Functional Class - example Minor Arterial Prin. Arterial Collector

  5. Some Characteristics • Major Arterial • Minor Arterial • Collectors • Local roads Accessibility Lane-miles Mobility Veh-miles Think of it like this: as you move from local roads upwards in functional classification towards major arterials, what happens to each of these 4 measures?  Answer: vehicle miles  and mobility go up.  Lane miles and accessibility go down. 

  6. Mobility Land Access Mobility vs. Accessibility Arterial Collectors Locals

  7. What?

  8. What Affects Highway Design? • Human, vehicle characteristics • Expected volume and its composition • Topography of the area • Functional classification • Level-of-service to be provided • Land use and environmental factors • Community concerns • Funding

  9. Basic Terms • Design Hourly Volume (DHV) • Expected number of vehicles in one hour in both directions • Directional Design Hourly Volume (DDHV) • Expected number of vehicles in one hour in one direction • Average Daily Traffic (ADT) • Number of vehicles in 24 hours in both directions • Average Annual Daily Traffic (AADT) • Number of vehicles in 24 hours in both directions

  10. Basic Terms (cont’d) • Design Speed • Choice speed to design for while balancing safety, mobility, community issues, and environmental concerns • Operating Speed • Average speed people drive with comfort • Speed limit • Maximum legal speed

  11. Basic Terms (cont’d) • Design Vehicle • Group of vehicles selected for establishing design control on highways with typical physical and operational characteristics • General classes: • Passenger car • Bus • Truck • Recreational vehicle

  12. Design Vehicles Which one? Largest with reasonable frequency?

  13. ?

  14. Roadway Median Roadway Shoulder Traveled way Traveled way Shoulder Clear Zone Clear Zone Right of Way Roadway Cross Section

  15. Cross Section Components

  16. Cross Section Components

  17. 1-2% 1-2% Travel Lanes • Purpose • Width • 10-12 feet • Arterials and freeway 12 feet • Cross slope Always?

  18. Shoulders • Purpose • Refuge area • Recovery area • Pavement support • Width • 2-12 feet • Slope • 2-4%

  19. Median • Purpose • Divide traffic • Recovery area • Storage area • Refuge area • Aesthetics • Width • Varied • Types • Raised • Flush • Depressed

  20. Right-Of-Way • Total land required for the construction of the highway • Needs to be wide enough to accommodate all the elements of highway cross section and planned widening of the highway, and all public utility facilities to be installed along the highway • Example: • 2-lane urban collector streets: 40-60ft • 2-lane urban arterials: 84ft

  21. Highway Alignment • Not all roads are straight and level • Vertical components • Grades • Curves • Horizontal components • Tangents • Curves

More Related