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ECGD 4121 – Transportation Engineering I Lecture 7

Faculty of Applied Engineering and Urban Planning. Civil Engineering Department. 2 nd Semester 2008/2009. ECGD 4121 – Transportation Engineering I Lecture 7. Studies of Traffic Engineering. Content. Speed Studies Volume Studies Travel Time & Delay Studies Parking Studies.

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ECGD 4121 – Transportation Engineering I Lecture 7

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  1. Faculty of Applied Engineering and Urban Planning Civil Engineering Department 2nd Semester 2008/2009 ECGD 4121 – Transportation Engineering I Lecture 7

  2. Studies of Traffic Engineering

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

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

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

  6. Data Sources

  7. Data Sources

  8. Data Sources

  9. Data Analyses

  10. Data Analyses

  11. Data Analyses

  12. Data Analyses

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

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

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

  16. Data Analyses

  17. Data Analyses Example: The afternoon peak hour traffic flow data for westbound traffic on a major road are: 4:45pm-5:00pm 400 vehicles 5:00pm-5:15pm 700 vehicles 5:15pm-5:30pm 600 vehicles 5:30pm-5:45pm 400 vehicles

  18. Data Analyses Data Analyses: • PHV = 400 + 700 + 600 + 400 = 2100 vehicles • PV15 = 700 vehicles • PHF = 2100/(4)(700) = 0.75 • DHV = 2100/0.75 = 2800 vehicles

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

  20. Traffic Volume Counting Types of Counts: • Cordon counts • Screen line counts • Intersection counts • Pedestrian volume counts • Periodic volume counts

  21. Traffic Volume Counting Adjustment of periodic counts: • Using data from continuous counting stations we can obtain the Hourly Expansion Factors • HEF = 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)

  22. Traffic Volume Counting Adjustment of periodic counts: • Daily 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)

  23. Traffic Volume Counting Adjustment of periodic counts: • Monthly 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)

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

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

  26. Travel Time & Delay Studies • 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 #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 vehicle • Driver: if possible try to balance the number of vehicles (overtaking vs. overtook)

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

  28. Parking Studies Definition of Parking Terms: • 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., 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.

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