1. Vehicle Flow

2. Homework Ch 3 # 1,4, 7, 15

3. Vehicle Flow How do vehicles operate in the system –capacity –speed –headway –density

4. Time Space Diagrams Show vehicle location vs. Time –one way or two way –any type of transportation system –used to find siding placement progression minimum headways throughput

5. Example Canal System - Cohoes and Schenectady are on the Erie Canal approximately 10 miles apart. There is a lock 3 miles from Schenectady. On the canal, barges cannot pass each other except in opposite directions ( the mules get tangled otherwise). The canal lock can raise or lower 1 barge in 20 minutes. it takes an additional 20 minutes to return the lock to its original position to handle another barge going in the same direction. Barges move at 5 mph. 3 barges can be accommodated at the lock either upstream or downstream until it is their turn to move through the lock. Barges leave Schenectady every 20 minutes and Cohoes every 30 minutes. Does the system work or should the schedule be revised?

6. Vehicle Following Spacing needed for stopping

7. Deceleration 3 types of deceleration –normal –emergency –instantaneous

8. Example Ch 3 # 2

9. Flow Concepts 4 variables –volume –speed –density –headway

10. Volume # of vehicles passing a given point in a given unit time q = n/T cars per hour does not tell you anything about speed or density

11. Speed 2 types –Space Mean Speed distance divided by time useful in determining vehicle flow characteristics –Time Mean Speed Spot speeds Radar gun not useful except for tickets

12. Example S i = 2 miles, i = 1 - 5 v 1 = 42 mph, v 2 = 39 mph, v 3 = 47 mph, v 4 = 50 mph m 1 = 3.1 min, m 2 = 2.8 min, m 3 = 3.3 min, m 4 = 3.0 min What is the difference, is it significant?

13. Density Concentration –vehicles per unit length –cars/mile

14. Headway Time or distance between two vehicles –h = 1/q gives the time headway –h = 1/k gives distance headway –which is more useful?

15. Relationships

16. q=uk –basic relationship Important points –jam density –jam speed –max volume

17. Relationships Shape of curves –what do they tell us?

18. Example Ch 3 # 8

19. Shock waves Happens when traffic is forced to change speed either slowing down or speeding up Can move either forward or backward

20. Example Ch 3, # 15

21. Pedestrians LOS based on –speed –flow rate –v/c ratio

22. Bike LOS Based on amount of hindrance

23. Examples Ch 4. # 1, 2

24. Homework Ch 4 #3,10, 12, 15, 16, 21,25,31, 36,37,48

25. Control of Vehicle Flows Control vehicles –minimize accidents –maximize effectiveness –transit –airports –roadways Channelization most common control

26. Control of Vehicle Flows Speed limits Control on Links –signage –lane width –number of lanes –headway rules

27. Headway Rules RR - uses block system

28. Headway Rules Aircraft –Airports 1 aircraft on runway at any time separation distances –2.5 miles between aircraft –10 miles horizontal / 2000 ft vertical in air –Control based on aircraft location Ground control for aircraft not on runway

29. Capacity Capacity based on mode # of vehicles per hour # of passengers per hour arrivals, departures per hour

30. Highways Capacity varies by road type –Freeways no controls, –Intersections traffic control –2 lane & 4 lane roads lead vehicle All use Level of Service

31. Level of Service LOS can be based on –delay per vehicle –speed –service flow 6 LOS A - F –A is best –F is worst

32. Determining Capacity Based on Roadway geometrics and traffic conditions For Freeways –can determine ideal conditions and from that a maximum capacity

33. Peak Hour Factor Measures demand peaking

34. Example Ch 4. # 11

35. Freeway Capacity LOS based on –density –speed –v/c For an LOS can find Maximum Service Flow (MSF)

36. MSF MSF = q max *(v/c) - ideal conditions SF = q = q max *N*f w *F HV Table 4.3.3 for heavy vehicle factors Table 4.3.2 for width factors

37. Capacity Restrictions Non recurring Recurring

38. Example Ch 4 # 14

39. Airports Capacity depends on landside and airside LOS is based on delay and total time Why are airports becoming shopping malls?

40. Rail Mass transit –LOS based on pass/seat, space/ pass, both peak and off peak AMTRAK –LOS based on wait time, comfort, pass/seat