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Areas of Practice
Lesson 7 Transportation
Term | Definition |
---|---|
Origin-Destination Survey | Review of travel information used to determine future traffic patterns |
Cross Tabulation Models | Groups variables to understand the correlation between different variables Allows for estimates of trip generation rates based on land use type, purpose or socioeconomic characteristics |
Trip End | Refers to the origin or destination point of a journey |
Trip Distribution | Examines where people are going |
Gravity Model | Provides trip estimates based directly on the proportional attractiveness of the zone and inversely proportional to the trip length |
Model Split | Deals with how people get to where they want to go, and the form of transportation that they use |
Average Annual Daily Traffic (AADT) | Amount of traffic on a roadway in a 24 hour period, average over a year |
Peak Hour Volume | Equals the hourly traffic during the peak period |
Seasonal Hour Volume | Peak hour volumes during different seasons |
Design Hour Volume (DHV) | The capacity of the roadway to handle traffic |
Traffic Assignment | Also known as trip assignment Allows us to use network models to predict the distribution of traffic for each roadway by the hour |
Vehicles Miles Traveled (VMT) | Measures the amount of travel for all vehicles in a geographic region over a period of time |
Road Design | Focuses on everything from the nature of street hierarchy to actual design guidelines for local streets |
Cross Section | An "ideal" road would have 10 foot travel lanes, 8 foot parking lanes, and a curb and planting strip Standards can be traced to Federal Highways Administration studies following WWII |
Typical Local Street Standards | 500 ft maximum tangents (curve) Use of Stop signs or speed humps 150 ft between intersections Clear sight distance of 75 ft |
Where do typical street designs come from? | Ancient Greeks |
What are the advantages of typical street design? | Ease of laying out streets Lots of lanes East of navigation (way finding) |
What are the disadvantages of typical street design? | Maximum of 4-way intersections - creates conflicts Tangent standards cannot always be met Grids result in the maximum pavement and utility line cost Streets can be used as parallel short-cuts during rush hour Grids can be very monotonous and boring |
Highway Capacity Manual | Published by the Transportation Research Board Provides concepts, guidelines, and procedures for computing highway capacity and quality of service based on road type |
Level of Service (LOS) | Range from A to F A LOS of a means there is free flowing traffic and F means heavy traffic congestion with severely reduced traffic speeds |
Federal-Aid Highway Act (1994) | Legislation established a National System of Interstate Highways, and required the Public Roads Administration to establish construction and operation standards for the Interstate Highway System |
Public Roads Administration (PRA) | Responsible for implementing the highway system |
Federal-Aid Highway Act of 1962 | Created federal mandate for urban transportation planning in the US It was passed at a time when urban areas were beginning to plan interstate highway routes Act call for continuing, comprehensive, and cooperative (3 c's) planning process |
What did the Federal-Aid Highway Act of 1962 also do? | Focused on providing funding for not just highways but also transit, pedestrian, and bicycle facilities |
Metropolitan Planning Organization (MPO) | Create to meet federal requirements for urban transportation planning |
How were MPO's established? | 1965, Bureau of Public Roads required the creation of planning agencies that would be responsible for carrying out the required transportation planning process As a result, MPO's were established |
Transportation Improvement Program (TIP) | List of upcoming transportation projects - covering a period of at least four years Prepared by the MPO's |
Transportation Demand Management | Used to describe strategies for the efficient use of transportation |
Car Sharing | Allows individuals to purchase a membership to a car service |
Flextime | Allows employees to work at different times beyond the regular 8 to 5 workday Reduces congestion on roadways during the peak commute times |
Guaranteed Ride Home | Provides commuters who regularly carpool or use transit with a reliable ride home if an emergency arises |
Commute Trip Reduction (CTR) | Is one of the tools of a total transportation demand management CTR programs provide commutes with resources and incentives to reduce their vehicle trips, particularly during peak commute hours |
Traffic Calming | Involves changes in street alignment, installation of barriers, and other physical measures to reduce traffic speeds and/or cut-through volumes, in the interest of street safety, and other public purposes |
Chicane | Series of staggered curb extensions on altering sides of the roadway |
Choker | Curb extension in the middle of a block |
Fuller or Partial Closure | Does not allow traffic beyond a certain point in the roadway |
Roundabouts | Require vehicles to circulate around a center island |
Speed Humps | Are raised areas placed across a road and are 3 to 4 inches tall |
Speed Table | Larger than a speed hump Flat-top and may have brick or another textured material on the flat surface |
Traffic Circles | Are raised landscapes islands located at the center of an intersection and can vary in size |
Parking Requiremetns | Standard parking stall in 9 ft by 18 ft |
Federal Aviation Administration (FAA) | National authority with powers to regulate all aspects of civil aviation. States are responsible for developing aviation plans that address air transportation across the state. |