Module 5-7 Flashcards
the study of interactions between travelers (including pedestrians, cyclists, drivers and their vehicles) and infrastructure ( including highways, signage, and traffic control devices).
Traffic Flow
It’s aim is to understand and develop an optimal transport network with efficient movement of traffic and minimal traffic congestion problems.
Traffic Flow
is the arithmetic mean of speed of all vehicles passing a point during a specified interval of time.
Time Mean Speed
Time Mean speed will always be greater than space mean speed since?
Standard Deviation cannot be negative
What happens if all the speed of the vehicles are the same?
Spot speed, time mean speed and space mean speed will also be the same
is the harmonic mean of speed of vehicles occupying a relatively long section of street or highway at a given instant.
Space Mean Speed
the number of vehicles per unit time passing a point in space and is gradually expressed in vehicles per hour.
Flow
the number of vehicles counted in a specified time interval.
Volume
Period of time (vehicles/hr)
Flow
is the ratio of the total hourly volume to the maximum rate of flow within the hour.
Peak Hour Factor ( PHF)
the number of vehicles per unit distance occupying a section of roadway at given instant time and is usually measured in vehicles per mile or per km.
Density (K)
ratio of the sum of the lengths of the vehicles to the length of the road section in which those vehicles are present.
Occupancy (O)
The rate of change of distance with respect to time and is usually measured in either miles per hour (mil/hr) or feet per second( ft/s)
Speed
The reciprocal of speed and is usually measured in mins/mile
Rate of Travel
The time elapsed between common points on successive vehicle.
Headway
The time elapsed between a rear of one vehicle to the front of the next.
Gap
The distance between a rear of one vehicle to the front of the next.
Clearance
Distance between the common points on successive vehicle.
Space
Is the term used to describe the average speed that a motorist would have if there were no congestion or other adverse conditions ( such as bad weather).
Free- flow speed
In traffic flow, the two most important densities are the:
Critical density (kc or Do)
Jam density ( kj or Dj)
The maximum density achievable under free flow
kc ( critical density)
The maximum density achieved under congestion
Kj ( jam density)
In general, ______ density is seven times the critical density.
Jam density
Is the maximum number of vehicles that can pass a given point on a lane or roadway for one hour, under the prevailing roadway and traffic conditions.
Maximum Capacity
The average of 24- hour traffic counts collected every day in the year. These counts are used to estimate highway user revenues, compute accident rates, and establish traffic volume trends.
Average Annual Daily Traffic ( AADT)
The the average of 24- hour traffic counts collected over a number of days greater than one day but less than a year. These counts are used for planning of highway activities, measuring current traffic demand, and evaluating existing traffic flow.
Average Daily Traffic ( ADT)
Is a measure used extensively in transportation planning for a variety of purposes.
Vehicle Miles of Travel ( VMT)
It measures the amount of travel for all vehicles in a geographic region over a given period of time, typically one year period.
VMT ( Vehicle miles of Travel)
It is formed when arrivals wait for a service or an opportunity such as the arrival of an accepted gap in a main traffic stream, the collection of tolls at a tollbooth or a parking fees at parking garage.
Queue
This queuing is the simplest having the deterministic arrivals, deterministic departure and one departure channel.
D/D/1 Queuing
Queuing that has exponentially distributed arrivals, deterministic departures and one departure channel.
M/D/1 Queuing
Queuing that has exponentially distributed arrivals, exponentially distributed departures and one departure channel.
M/M/1 Queuing
