Transportation Planning Flashcards
Trip Generation
Number of trips that a site is likely to generate
Origin-Destination Survey
Requires that roadblocks be set up along major routes. The imaginary line that denotes the boundary of the study area is known as the cordon line. Motorists within the cordon area can then be sampled and asked questions on where they are coming from (address or point of origin) and where they are going (destination).
Cross Tabulation Models
Estimates of trip generation rates based on land use type, purpose, or socioeconomic characteristics.
Trip Generation Rate for Office Space
11 daily trip ends for every 1,000 square feet of general office space
Trip Generation Rate for Single Family Residence
9.6 daily trip ends per single family residential dwelling
Trip Generation Rate for Apartments
6.6 daily trip ends per apartment unit
Trip Generation Rate for Shopping Centers
43 daily trip ends per 1,000 square feet of shopping center space
Trip Generation Rate for Industrial
7 daily trip ends per 1,000 square feet of light industrial development
Trip Ends
Origin or destination for a trip
Trip Distribution
A region or area is often divided into traffic zones and provides information on how many trips are made between each zone and every other zone. Provides information on trip distances, time and cost, the nature of the trip, socioeconomic characteristics, and the nature of the transportation system.
Gravity Model
Used to provide trip estimates based on the proportional attractiveness of the zone (the “gravitational pull”) and inversely proportional to the trip length.
Modal Splits
Getting where you want to go using combinations of walking, biking, public transit, car use, etc.
AADT
(Average Annual Daily Traffic) is the amount of traffic on a roadway in a 24 hour period, averaged over a year
Peak Hour Volume
hourly traffic during the peak period
Seasonal Hour Volume
peak hour volume during different seasons
DHV
Design Hour Volume - capacity of the roadway to handle traffic
Traffic Assignment
Use of network models to predict the distribution of traffic for each roadway by the hour. Peak volumes can then be compared with DHV to see which, if any, roadways are going to experience traffic over their design capacity
VMT
Vehicle Miles Traveled - measure of vehicular mobility obtained from travel inventories. High VMT means more vehicles on the road for employment, errands, etc.
Functional Classification
Grouping streets and highways into local or highways, and arterials vs. collectors
Typical Local Street Dimensions
500 feet maximum tangents;
Use of stop signs or speed bumps to reduce vehicle speed;
150 feet between intersections;
Clear sight distances of 75 feet.
Grid
a street pattern common in ancient cities and often advocated by New Urbanist planners for facilitating pedestrian access; variants of the classic grid include the block grid, curved block grid, and curved grid
Loop Streets
May have minimum and maximum depth standards, looping within the grid
Cul-De-Sacs
with maximum length and minimum radius standards of 400-450 feet long and 40-foot turn-around radius
Plaza and hammerhead street style
Usually insufficient for vehicle turn-around
Typical street gradients
Minimum is 0.5%. In areas with cold winters the maximum gradient is 5%; it is 8% for areas with mild winters.
Highway Capacity Manual
Provides concepts, guidelines, and procedures for computing highway capacity and quality of service based on road type
Federal-Aid Highway Act of 1944
Designating 65,000 km of interstate highways. These highways, to be selected by state highway departments, authorized the highway system but did not provide funding
Public Roads Administration
- Designated 60,640 km of interstate highways and implemented highway system.
Federal-Aid Highway Act of 1952
authorized $25 million for the construction of interstate highways and another $175 million two years later