LE 1 Concepts Flashcards
a field or branch of civil engineering that deals with the application of technology and scientific principles to the movement of people and goods
Transportation Engineering
phase of transportation engineering that deals with the planning, geometric design, and traffic operatios
Traffic Engineering
Flow occurring at long sections of road where vehicles are not required to stop by any cause external to the traffic stream
Uninterrupted Flow
Flow occurring at intersections or driveways where vehicles are required to stop by any cause outside the traffic stream such as traffic signs (‘STOP’ or ‘YIELD’), traffic signal lights, etc.
Interrupted Flow
the number of vehicles passing a point during a specified period of time
Flow rate or volume
rate of motion in distance per unit time
Speed
the number of vehicles in a given length of road at an instant point in time
Density or concentration
TRUE OR FALSE
Time Mean Speed ≥ Space Mean Speed
TRUE
time interval between passage of consecutive vehicles at a
specified point on the road
Headway
distance between 2 vehicles measured from the front
bumper of a vehicle to another
Spacing
as density ________, speed ________
increases; decreases
the maximum hourly rate at which vehicles can reasonably be expected to traverse a point or uniform section of a lane or roadway during a given time period under prevailing roadway, traffic and control conditions
Capacity
a qualitative description of how a certain facility is performing
Level of Service (LOS)
design hour factor = (design or peak hour volume / 24-hr volume)*100%
k factor
D = volume in predominant direction / total volume
directional distribution (directional split)
multiply passenger car equivalent factors (PCEF) to convert different vehicle types into a standard car unit
36
pcu or passenger car unit
It involves
planning, evaluation, and programming
of transportation facilities , including roadways,
transit terminals, parking, pedestrian facilities,
bikeways, and goods movement.
Transportation Planning
CLASSIFICATION
OF URBAN LAND DESCRIBING
THE CONDITION OF
PERFORMED URBAN ACTIVITY
LAND USE
Land Use - Transport Interaction
Land Use - Activity Demand - Travel Demand - Transportation Infrastructure - Accessibility - Land Use
Models establish relationships
between land use and travel demand patterns.
Forecasting Models
Main Functions are to accommodate road traffic
demand and to offer a network on which mass transport network can be established
Road Network
Goal of Travel Demand Forecasting
- Estimate the impact of any transportation
improvement projects on transportation - Estimate the impact of any
policies on the
transportation system on transportation
a multi stage
process , and there are several different techniques
that can be used at each stage
Travel Demand Forecasting
Basic Steps of Travel Demand Forecasting
(0) Database Development
(1) Trip Generation
(2) Trip Distribution
(3) Modal Split
(4) Traffic Assignment
Calculate the number of trips starting in each zone for
a particular trip purpose
Trip Generation
Produce a table of the number of trips starting in each zone and ending up in each other zone
Trip Distribution
Complete the allocation of the various trips among the
available transportation systems (bus, train,
pedestrian, and private vehicles)
Modal Split
Identify the specific routes on each transportation
system that will be selected by the travelers
Traffic Assignment
should be
homogeneous as possible in their land use
and/or population composition
Zoning Criteria
is a one way movement from a point of origin to a point of destination
Trip
future number of trips T’ij is
present trips Tij multiplied by growth factors
Growth rate method
trip rates are established per
household category or land use type; estimated
future trips is size multiplied by trip rate
Category analysis
future number of trips is a
function of socio-economic variables/factors
Regression model
Disadvantages of Present Pattern Method
- Complete OD Matrix is required
- Change of land use is not considered
- Errors are expanded with the same rate
Advantages of Model Method
- Trip resistance is considered
- Structure of model is easy to understand
- Complete OD matrix is not required
Disadvantages of Model Method
- Index of resistance is arbitrary
- Trip distribution within zone is difficult to treat
- Trip distribution for near zone pairs are overestimated
Cost of using a mode for conducting the trip
Generalized Cost
Based on economic
theory that there is an
__________ relationship
between demand and
cost
inverse
Methods of Network Assignment
*All-or-nothing
*Constant assignment ratio
*Incremental assignment
