Deals with the planning, geometric design and traffic operations of roads, streets and highways, their networks, terminals, abutting lands and relationships with other modes of transportation for the achievement of safe, efficient and convenient movement of persons and goods.
Traffic Engineering
Applies engineering principles to help solve transportation problems, and brings into play a knowledge of psychology and habits of users of the transportation systems, aside from technical foundations.
Traffic Engineering
The greatest obstacles a professional traffic engineer faces in applying sound principles of traffic engineering is the fact that “________________________.”
everyone is a traffic expert
provide a list or graphic display of existing information, such as street widths, parking spaces, transit routes, traffic regulations and so forth. (ex: available parking spaces and traffic regulations)
Inventories
These are the existing engineering records,
available in government agencies and departments. This information is used to prepare an inventory of the relevant data. These include the results of surveys, which may involve field measurements and/or aerial photography.
Administrative Studies
These involve the collection of data under operational conditions and include studies of speed, traffic volume, travel time and delay, parking and crashes since these are carried out by the traffic engineer to evaluate current conditions and develop solutions.
Dynamic Traffic Studies
These are conducted to estimate the distribution of speeds of vehicles in a stream of traffic at a particular location on a highway.
Spot Speed Studies
This is carried out by recording the speeds of a sample of vehicles at a specified location.
Spot Speed Study
This is defined as the rate of movement of the vehicle; it is usually expressed in kilometers per hour(kph) or miles per hour(mph).
speed of a vehicle
Speed characteristics identified by such a study will be valid only for the traffic and environmental conditions that exist at the ________________.
time of the study
These collect on speeds and volume at the same time. They are laid across the lane in which data are to be collected.
Pneumatic Road Tubes and Induction Loops
A rectangular wire loop buried under the roadway surface. It operates on the principle that a disturbance in the electrical field is created when a motor vehicle passes across it.
Inductive Loop Detector
significant values that are needed to describe speed characteristics
Average Speed
Median Speed
Modal Speed
ith-Percentile Spot Speed
Pace
Standard Deviation of Speeds
This is the arithmetic mean of all observed vehicle speeds (which is the sum of all spot speeds divided by the number of recorded speeds).
Average Speed
This is the speed at the middle value in a series of spot speeds that are arranged in ascending order.
Median Speed
This is the speed value that occurs most frequently in a sample of spot speeds.
Modal Speeds
This is the spot speed value below which i percent of the vehicles travel.
ith-Percentile Spot Speed
This is the range of speed-usually taken at 10 ,i/hr intervals - that has the greatest number of observations.
Pace
This is a measure of the spread of the
individual speeds.
Standard Deviation of Speeds
These are conducted to collect data on the number of vehicles and/or pedestrians that pass a point on a highway facility during a specified time period.
Traffic volume studies
Traffic volume studies are usually conducted when certain volume
characteristics are needed, some of which follow:
Average Annual Daily Traffic (AADT)
Average Daily Traffic (ADT)
Peak Hour Volume (PHV)
Vehicle Classification (VC)
Vehicle Miles of Travel (VMT)
The average of 24-hour counts collected every day of the year.
Average Annual Daily Traffic (AADT)
The average of 24-hour counts collected over a number of days greater than one but less than a year.
Average Daily Traffic (ADT)
The maximum number of vehicles that pass a point on a highway during a period of 60 consecutive minutes.
Peak Hour Volume (PHV)
