ECGD 4121 – Transportation Engineering I Lecture 7 Faculty of Applied Engineering and Urban Planning Civil Engineering Department 1 st Semester 2009/2010 1

Studies of Traffic Engineering 2

3 Content Speed Studies Speed Studies Volume Studies Volume Studies Travel Time & Delay Studies Travel Time & Delay Studies Parking Studies Parking Studies

Speed Studies Basic Methods: Pneumatic road tube Pneumatic road tube Inductive loop detectors Inductive loop detectors Video detectors Video detectors Others Others 4

Speed Studies Speed characteristics expressed using: Average speed (arithmetic mean) Average speed (arithmetic mean) Median speed Median speed Modal speed Modal speed i th percentile spot speed (85 th, 95 th ) i th percentile spot speed (85 th, 95 th ) Standard deviation Standard deviation Basic statistic analyses Basic statistic analyses 5

6 Data Sources

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9 Data Analyses

10 Data Analyses

11 Data Analyses

12 Data Analyses

Volume characteristics expressed using: Average Annual Daily Traffic (AADT)Average Annual Daily Traffic (AADT) Average Daily Traffic (ADT)Average Daily Traffic (ADT) Peak Hour Volume (PHV)Peak Hour Volume (PHV) Vehicle Miles of Travel (VMT)Vehicle Miles of Travel (VMT) Vehicle Classification (VC)Vehicle Classification (VC) 13 Data Analyses

14 Data Analyses Average Annual Daily Traffic (AADT) Vehicles per day (VPD) in both directionsVehicles per day (VPD) in both directions Expressed as average of 24 hours counts for 365 days (1 year)Expressed as average of 24 hours counts for 365 days (1 year) Used for determining and assigning traffic trends, feasibility studies, etcUsed for determining and assigning traffic trends, feasibility studies, etc

Average Daily Traffic (ADT) Vehicles per day (VPD) in both directionsVehicles per day (VPD) in both directions Expressed as average of 24 hours counts for a number of days less than 1 yearExpressed as average of 24 hours counts for a number of days less than 1 year Used for planning, measurement of current demand, evaluate traffic flowUsed for planning, measurement of current demand, evaluate traffic flow 15 Data Analyses

16 Data Analyses

Example: The afternoon peak hour traffic flow data for westbound traffic on a major road are: 4:45pm-5:00pm400 vehicles 5:00pm-5:15pm700 vehicles 5:15pm-5:30pm600 vehicles 5:30pm-5:45pm400 vehicles 17 Data Analyses

Data Analyses: PHV = = 2100 vehicles PHV = = 2100 vehicles PV 15 = 700 vehicles PV 15 = 700 vehicles PHF = 2100/(4)(700) = 0.75 PHF = 2100/(4)(700) = 0.75 DHV = 2100/0.75 = 2800 vehicles DHV = 2100/0.75 = 2800 vehicles 18 Data Analyses

Methods of Counting: Manual methodsManual methods Automatic methodsAutomatic methods Surface detectors such as pneumatic road tubes Surface detectors such as pneumatic road tubes Subsurface detectors such as magnetic or electric contact devices Subsurface detectors such as magnetic or electric contact devices 19 Traffic Volume Counting

Types of Counts: Cordon countsCordon counts Screen line countsScreen line counts Intersection countsIntersection counts Pedestrian volume countsPedestrian volume counts Periodic volume countsPeriodic volume counts 20 Traffic Volume Counting

Adjustment of periodic counts: Using data from continuous counting stations we can obtain the Hourly Expansion FactorsUsing data from continuous counting stations we can obtain the Hourly Expansion Factors HEF = total volume for 24-hr period/volume for a particular hourHEF = total volume for 24-hr period/volume for a particular hour HEF is used to expand counts of durations shorter than 24 hr to 24-hr volumes (must use HEF obtained from similar class of roads)HEF is used to expand counts of durations shorter than 24 hr to 24-hr volumes (must use HEF obtained from similar class of roads) 21 Traffic Volume Counting

Adjustment of periodic counts: Daily Expansion Factors (DEF) = Average total volume for week/average volume for particular dayDaily Expansion Factors (DEF) = Average total volume for week/average volume for particular day DEF is used to determine weekly volumes from counts of 24-hr duration (must use DEF obtained from similar class of roads)DEF is used to determine weekly volumes from counts of 24-hr duration (must use DEF obtained from similar class of roads) 22 Traffic Volume Counting

Adjustment of periodic counts: Monthly Expansion Factors (MEF) =AADT/ADT for particular monthsMonthly Expansion Factors (MEF) =AADT/ADT for particular months MEF is used to determine AADT from ADT for a given month (must use DEF obtained from similar class of roads)MEF is used to determine AADT from ADT for a given month (must use DEF obtained from similar class of roads) 23 Traffic Volume Counting

Travel Time & Delay Studies Studying the route from “A” to “B” to: Determine travel timeDetermine travel time Determine route efficiencyDetermine route efficiency Identify delay locationsIdentify delay locations Evaluate “before & after” performanceEvaluate “before & after” performance Feasibility studiesFeasibility studies 24

Travel-time estimation: The moving car method 25 Travel Time & Delay Studies

Requires one testing vehicle, one driver, and three observers on board.Requires one testing vehicle, one driver, and three observers on board. Observer #1: counts mean time the testing car takes to travel eastward and westward.Observer #1: counts mean time the testing car takes to travel eastward and westward. Observer #2: counts the number of vehicles traveling in opposite directionObserver #2: counts the number of vehicles traveling in opposite direction Observer #3: counts the number of vehicles that overtook and are overtaken by the testing vehicleObserver #3: counts the number of vehicles that overtook and are overtaken by the testing vehicle Driver: if possible try to balance the number of vehicles (overtaking vs. overtook)Driver: if possible try to balance the number of vehicles (overtaking vs. overtook) 26 Travel Time & Delay Studies

The characteristics of the parking facility and parking behaviorThe characteristics of the parking facility and parking behavior Parking facility: full time and part timeParking facility: full time and part time Parking behavior: short time and long time – rate of use of a parking spaceParking behavior: short time and long time – rate of use of a parking space 27 Parking Studies

Definition of Parking Terms: Space-hour: the use of a single parking space during a period of time.Space-hour: the use of a single parking space during a period of time. e.g., one space-hour can be either one vehicle parked one hour at one parking lot, or two vehicles parked 30 minutes each at one parking lot.e.g., one space-hour can be either one vehicle parked one hour at one parking lot, or two vehicles parked 30 minutes each at one parking lot. e.g., the maximum capacity of a full time (8:00 AM – 6:00 PM) garage with 200 parking lots is: (200 vehicles)(10 hours) = 2000 veh.hr.e.g., the maximum capacity of a full time (8:00 AM – 6:00 PM) garage with 200 parking lots is: (200 vehicles)(10 hours) = 2000 veh.hr. 28 Parking Studies