Traffic Engineering Studies

Question 1

What are the purposes of traffic engineering studies?

Answer 1

• to determine the characteristics of highway system users and their vehicles
• to monitor system operation
• to identify problem areas
• to assist in developing appropriate remedial action

Question 2

Mean

Answer 2

average

Question 3

Median

Answer 3

50th percentile value - half of values are more, half are less

Question 4

Mode

Answer 4

the most frequent value of x

Question 5

Standard deviation

Answer 5

measure of dispersion

Question 6

Regression-to-the-mean

Answer 6

After a period of comparatively high crash frequency, it is statistically probable that the following period will have a comparatively low crash frequency

Question 7

Delay

Answer 7

additional travel time experienced

Question 8

Spot Speed

Answer 8

instantaneous speed of a vehicle passing a point on the roadway

Question 9

Journey Speed

Answer 9

distance divided by the total journey time

Question 10

Running Speed

Answer 10

distance divided by the running time

Question 11

Time Mean Speed

Answer 11

arithmetic mean of spot speeds

Question 12

Space Mean Speed

Answer 12

mean travel speed of vehicles traveling a roadway segment of a known distance

Question 13

Capacity

Answer 13

maximum traffic flow that can be accommodated in a facility during a given time period under prevailing roadway, traffic, and control conditions

Question 14

Purpose of travel time studies

Answer 14

Evaluate the quality of traffic movement along a route and determine the locations, types, and extent of traffic delays

Question 15

Travel Time

Answer 15

elapsed time of travel

Question 16

Running Time

Answer 16

time that the vehicle is actually in motion

Question 17

Travel speed

Answer 17

overall average speed

Question 18

Running speed

Answer 18

distance divided by running time

Question 19

Fixed Delay

Answer 19

regardless of the amount of traffic

Question 20

Operational Delay

Answer 20

interference from other components of the traffic stream

Question 21

Control Delay

Answer 21

delay attributable to the intersection traffic control device

Question 22

Purpose of No Passing Zone study

Answer 22

to establish limits on the roadway which permit the passing driver the necessary sight distance to allow a safe completion of the passing maneuver

Question 23

Spot speed study

Answer 23

measures individual speeds of a sample of vehicles passing a point on the roadway

Question 24

When should speed studies be conducted?

Answer 24

during off peak hours, when traffic is free flowing

Question 25

What sample size is needed for spot speed studies?

Answer 25

100 vehicles per lane

Question 26

Speed Zoning

Answer 26

establishment of safe, reasonable speed limits for certain sections of highway where the statutory speed limits do not fit the roadway and traffic conditions

Question 27

A posted speed limit must be within ___ mph of the ___ percentile speed of free-flowing traffic

Answer 27

5 mph 85th

Question 28

What factors may be considered when establishing speed limits?

Answer 28

1) Road characteristics, shoulder condition, grade, alignment, sight distance 2) Pace 3) Roadside development and environment 4) Parking practices and pedestrian activity 5) Reported crash experiencer at least a 12-month period

Question 29

Pedestrian walking speed

Answer 29

3.5 feet per second

Question 30

AADT

Answer 30

average annual daily traffic average 24-hour volume at a given location over a full 365-day year

Question 31

ADT

Answer 31

average daily traffic average 24-hour volume recorded for some period less than a year

Question 32

AWT

Answer 32

average weekday traffic average daily traffic, M-F

Question 33

DHV

Answer 33

design hourly volume one-hour volume used as the basis of design or traffic operational decisions

Question 34

Collision studies

Answer 34

Traffic safety studies that use crash reports to assess safety by evaluating number, type, and severity of crashes along a roadway segment or intersection

Question 35

Gap study

Answer 35

determines the number of gaps in vehicle traffic that are of adequate length to permit pedestrians to cross the street

Question 36

Site Impact Studies

Answer 36

determine the needs for any improvements to the adjacent and nearby transportation system to maintain a satisfactory level of service, safety, and access to a proposed land development

Question 37

Site Impact Analysis steps

Answer 37

- site traffic generation - site traffic distribution and assignment - non-site traffic forecast - analysis of LOS at intersections - site access improvements - internal site circulation and parking analysis

Question 38

By federal law, every urbanized area over ________ population must have a transportation planning process

Answer 38

50,000

Question 39

Areas with populations greater than __________ are designated transportation management areas (TMAs)

Answer 39

200,000