ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Steven Boice Portland State University M.S. Civil Engineering Candidate A Thesis defense presented in the partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in CIVIL ENGINEERING July 28, 2008

2 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Presentation Outline  Introduction  Study Area  Methodology  Analysis  Results  Outlook

3 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Presentation Outline  Introduction  Study Area  Methodology  Analysis  Results  Outlook

4 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Introduction Variable Speed Limit System  Speed limits that change based on real time road, traffic, and weather conditions –Road Slippery pavement, visibility –Traffic Density, speed, truck percentages –Weather Rain, snow, ice, fog  Speed limits, advisories, regulatory prohibitions presented to drivers via overhead gantries –Sign centered over each lane –Enforced via radar/camera  Speed limit changes based on series of algorithms  Speed limits change in order to: –Postpone or prevent freeway breakdown –Reduce shock speeds –Increase lane homogeneity (speed/flow) –Increase safety –Increase capacity

5 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Introduction Variable Speed Limit System  Speed limits, advisories, regulatory prohibitions presented to drivers via overhead gantries –Sign centered over each lane

6 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Introduction Thesis Objective  Address VSL impacts on key traffic flow parameters –Bottleneck location/reoccurrence –Bottleneck properties (shock speed, pre-queue flow, queue discharge flow) –Lane harmonization (flow/speed)  Address by conducting empirical before/after analysis on a German Autobahn –Use real data collected from roadway sensors along Autobahn 99 with VSL in and out of operation

7 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Variable Speed Limit: Concept Maintain constant flow

8 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Introduction Thesis Motivation  VSL - Germany, United Kingdom, Netherlands, Australia –Large emphasis on safety –Large decrease in rear end crashes –Large decrease in speed differential –20-30% reduction in crash rates (Germany) –30% reduction in injury crashes (M25 U.K.) –Little emphasis on impacts of traffic flow parameters –15% increase in shoulder lane (M25 U.K.) –Increase in weekday traffic volumes (M25 U.K.) –No improvement in freeway performance (A2 Netherlands)

9 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Introduction Thesis Background  Graduate Research Assistant –Intelligent Transportation Systems Laboratory Empirical Analysis of German and U.S. traffic sensor data and impact on Driver Assistance Systems o Funded by BMW o Analysis of A9  Rodger Lindgren –Analysis of A5  “Connections” allowed for access to A99 data  Opportunity to compare US and German freeways

10 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Outline  Introduction  Study Area  Methodology  Analysis  Results  Outlook

11 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Study Area Autobahn 99 - Munich, Germany A99 Study Area A99 = ¾ ring around City of Munich, Germany

12 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Study Area Autobahn 99  Constructed in 1930’s  Total 41 kilometers (A995 to A96)  ¾ ring around city of Munich  Considered one of busiest roadways in Europe –ADT = ?  No ramp metering  Connects roadways to City of Munich –A96 –A8 –A92 –A9 –A94 –A995

13 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Study Area A99 Site Facts ParameterAutobahn 99 NorthboundSouthbound Length15.6 km16.3 km Cross section2-4 lanes Hard shoulderYes ADT?? Speed limitPassenger cars - Only when VSL active Trucks – 80km/hr (all time) Passenger cars - Only when VSL active Trucks – 80km/hr (all time) Ramps3 off/4 on4 off/3 on Mainline detectors (dual loop)1314 Ramp detectors (dual loop)56 Detector spacing320 m – 2,917 m505 m – 2,250 m VSL sign gantries1012 VSL sign gantry spacing1,070 m – 2,030 m663 m – 2,250 m

14 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Study Area Autobahn 99 (hard shoulder) Lane opened in dense traffic

15 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Study Area Autobahn 99

16 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Outline  Introduction  Study Area  Methodology  Analysis  Results  Outlook

17 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology A99 Data Summary Detector data Data Flow (cumulative over 1 minute) (lane and vehicle specific) Velocity (averaged over 1 minute) (lane and vehicle specific) Data availability October 10, 2003-October 25, 2003 November 1-November 30, 2003 (57 days) Variable Message Sign Data DataSpeed Limit Driver Information Warnings/Prohibitions Data AvailabilityOctober 10, 2003-October 24, 2003 November 11, 2003-November 30, 2003 System offOctober 25, 2003-November 10, 2003 (17 days)

18 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology A99 Data Summary Detector Data Availability Days with VSLDays without VSL WeekdayWeekendWeekdayWeekend

19 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology Transformed cumulative curves  Transformed cumulative curves (e.g. Newell, Cassidy & Windover) –Vehicle count –Time-averaged speed Transformations to heighten visual resolution: o Oblique axis o Horizontal shift with vehicle conservation o Retain highest level of resolution (one-minute) o Identify bottleneck activations and deactivations.

20 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck: Definition  An “active” bottleneck is a restriction that separates upstream queued traffic from downstream un-queued traffic  An “active” bottleneck is de-activated when there is either a decrease in demand or when a queue spills back from a downstream bottleneck

21 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology Transformed Cumulative Curves N(x,t)

22 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology Transformed Cumulative Curves N(x,t)-q 0 t´ N(x,t) q 0 =5180 vph

23 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology Transformed Cumulative Curves 14:0014:1514:3014:4515:0015:1515:3015:4516:00 Time N(x,t) Cumulative Count 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000 N(x,t)-q 0 t´

24 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology Transformed Cumulative Curves 14:0014:1514:3014:4515:0015:1515:3015:4516:00 Time N(x,t) Cumulative Count N(x,t)-q 0 t´

25 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology Queuing Diagram x 1 x 2 Ref. Veh. Trip Time Number Trip Time j Time, t j t1t1 Travel Direction N(x j,t) N(x 1,t) N(x 2,t)

26 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology Queuing Diagram Excess Accumulation x 1 x 2 Time, t Travel Direction N(x j,t) Excess Travel Time=Delay N(x 1,t) N(x 2,t) t2t2 k

27 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Southbound (MQ) (AQ) (m) Methodology Time Space Diagram Speed (km/hr)

28 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology Time Space Diagram Warning/Prohibition (km/hr) 1 = Speed 60 km/hr 2 = No passing Trucks 3 = 4=

29 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology Flow - Occupancy

30 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Outline  Introduction  Study Area  Methodology  Analysis  Results  Outlook

31 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Analysis –bottleneck location/reoccurrence –Bottleneck characteristics Shock speed, prequeue, queue discharge –Lane harmonization (flow/speed)

32 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN  Go through 1 Bottleneck Diagnosis –Show audience how it is done Walk them through October 16, 2003 southbound –Include slides similar to A9 slides (included for June 27, 2002) –Show how shock speed, pre-queue, and queue discharge flows are calculated (see A9 slides) –Diagnosis Walk audience through 1 diagnosis –Walk audience through what VSL system was doing

33 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Speeds Northbound A9 June 27,

34 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Speeds Northbound A9 June 27,

35 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 Station 380 N(x,t)-q 0 t′, q 0 =5170 veh/hr Station Off Ramp :4514:5014:5515:0015:0515:1015:1515:2015:2515:3015:3515:4015:4515:50 Time off 630

36 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 Stations 380–390–420 N(x,t)-q 0 t′, q 0 =5170 veh/hr Station On Ramp Station 390 Station Off Ramp Time 630

37 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN N(x,t)-q 0 t′, q 0 =5170 veh/hr Station 390 Station 380 Flow Bottleneck Activation June 27, 2002 Stations 380–390–420 Time 630

38 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN :1515:2015:2515:30 Time 15:21 89 km/h 70 km/h V(380,t)-b 0 t′, b 0 =3300 km/hr 2 Bottleneck Activation June 27, 2002 Station 380 Speed 630

39 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN N(x,t)-q 0 t′, q 0 =5170 veh/hr Station 420 Station 390 Station 380 Flow :1515:2015:2515:30 Time 15: V(380,t)-b 0 t′, b 0 =3300 km/hr 2 V(390,t)-b 0 t′, b 0 =4335 km/hr :1515:2015:2515:30 Time 15: :1515:2015:2515:30 Time V(420,t)-b 0 t′, b 0 =4850 km/hr 2 15: Bottleneck Activation June 27, 2002 Stations 380–390–420 Time 630

40 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27,

41 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, :21 15:24 15:34 15:41 15:42 15:47 15:

42 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN N(x,t)-q 0 t′, q 0 =5170 veh/hr Station 350 Station Off-Ramp Station 340 Station On-Ramp station 380 Bottleneck Activation June 27, 2002 Stations 320–340–350–380 Time 630

43 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN N(x,t)-q 0 t′, q 0 =5170 veh/hr Station 380 Flow station 380 Bottleneck Activation June 27, 2002 Stations 320–340–350–380 Time 630

44 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN N(x,t)-q 0 t′, q 0 =5170 veh/hr Station 350 Station 320 Station 340 Station 380 Flow station :1515:2015:2515:30 Time 15:23 84 V(350,t)-b 0 t′, b 0 =4200 km/hr :1515:2015:2515:3015:3515:4015:45 Time 15: V(340,t)-b 0 t′, b 0 =5600 km/hr :1515:2015:2515:3015:3515:4015:45 Time 15: V(320,t)-b 0 t′, b 0 =6000 km/hr 2 Bottleneck Activation June 27, 2002 Stations 320–340–350–380 Time 630

45 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN  Active bottleneck located between detectors 380 and 390.  Activated at 15:21.  Queue propagated as far as detector 630.  Unrestricted traffic downstream. Bottleneck Activation June 27,

46 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 Direction of Travel 15:21 19:40 17:40 18:44 17:28 17:35 17:38 15:24 15:34 15:41 15:42 15:47 15:58 19:

47 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 Direction of Travel 15:21 19:40 17:40 18:44 17:28 17:35 17:38 15:24 15:34 15:41 15:42 15:47 15:58 19:

48 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Direction of Travel 15:21 19:40 17:40 18:44 17:28 17:35 17:38 15:24 15:34 15:41 15:42 15:47 15:58 19:18 Bottleneck Activation June 27,

49 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Direction of Travel 15:21 19:40 17:40 18:44 17:28 17:35 17:38 15:24 15:34 15:41 15:42 15:47 15:58 19:18 Bottleneck Activation June 27,

50 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 Stations 380–390–420 N(420,t) N(390,t) N(380,t) :0016:0017:0018:0019:00 Time N(x,t)-q 0 t, q 0 =5178 veh/hr 630

51 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 N(420,t) N(390,t) N(380,t) :0016:0017:0018:0019:00 Time N(x,t)-q 0 t, q 0 =5178 veh/hr 15:21 17:35 17:40 18:45 19:

52 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 N(380,t) :0016:0017:0018:0019:00 Time N(x,t)-q 0 t, q 0 =5178 veh/hr 15:21 17:35 17:40 18:45 19:

53 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 N(380,t) :0016:0017:0018:0019:00 Time N(x,t)-q 0 t, q 0 =5178 veh/hr 15:21 17:35 17:40 18:45 19: vph 5370 vph 1 630

54 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 N(380,t) :0016:0017:0018:0019:00 Time N(x,t)-q 0 t, q 0 =5178 veh/hr 15:21 17:35 17:40 18:45 19: vph 5370 vph 5410 vph

55 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation Northbound A9 Outflow Summary at

56 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation – October 16, 2003

57 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Southbound 9:53 8:02 9:44 8:18 8:25 9:29 9:28 9:49 7:56 8:55 10 km/hr Pre-queue Flow = 4630 Median lane = 1848 Center lane = 1835 Shoulder lane = 948 Queue Discharge Flow = 4134 Queue Discharge Flow =

58 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Diagnosis Station 130 Station 120 Station 110 Station Off Ramp – On Ramp

59 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Diagnosis Flow Station 130 Uninterrupted flow between Stations 130 and 140 Station

60 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Diagnosis  Continue diagnosis details for October 16 here –Similar to A9 as shown in previous slides

61 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Diagnosis

62 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Diagnosis

63 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN VSL Dynamics

64 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN VSL Dynamics posted speed

65 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN VSL Dynamics Warnings/prohibitions

66 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN VSL Dynamics text information

67 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN VSL Dynamics Posted speed vs Measured speed  VSL

68 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Measured speed vs warnings prohibitions  Warnings/prohibitions

69 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Sign AQ 215a = -1 km/hr Sign AQ 214 = -6 km/hr Bottleneck activation between Bottleneck shift upstream between Bottleneck deactivated Detector speed minus posted speed

70 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Average trucks speeds km/hr above mandatory 80 km/hr Speed Variance: Trucks Detector speed (actual) – Mandatory truck speed (80 km/hr)

71 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Speed Variance: Trucks Detector speed (actual) – Variable speed (posted) Sign AQ 215a = -5 km/hr Sign AQ 214 = -13 km/hr

72 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Speed compliance

73 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN

74 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN

75 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Flow – Density Relationship: Detector Station 47/Message Sign AQ :14 – Speed reduced to 80 km/hr. 6:00 – Speed limit activated with posted speed of 120 km/hr. 7:05 - Speed limit de-activated. No passing restriction changes to “Congestion” indication on sign vph 3497 vph 4197 vph 4002 vph 3728 vph 3155 vph 5:55 – No passing for trucks prohibition activated 6:09 – Speed reduced to 100 km/hr 6:36 Speed reduced to 60 km/hr 92 km/hr 83 km/hr 77 km/hr 62 km/hr 76 km/hr 53 km/hr Bottleneck activation between km/hr 100 km/hr 80 km/hr 60 km/hr No Passing “TRUCKS ONLY”Congestion Flow-Density points were plotted for each state at which the variable speed changed and also for constant states for detector station 47. As can be seen, the speed decreases for each point (1-5)

76 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Southbound 9:53 8:02 9:44 8:18 8:25 9:29 9:28 9:49 7:56 8:55 10 km/hr Pre-queue Flow = 4630 Median lane = 1848 Center lane = 1835 Shoulder lane = 948 Queue Discharge Flow = 4134 Queue Discharge Flow = WITH VSL

77 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN 8:34 9:05 8:13 8:07 8:02 7:56 8:43 8:49 9:00 8:27 8:54 7:48 7:27 8:33 9:41 8:26 8:34 8:57 9:16 8:53 8:18 8:21 9:18 9:078:278:37 8:22 8:41 7:478:00 9:16 8:38 8:50 9:32 7:35 8:10 15 km/hr 20 km/hr 5 km/hr Pre-Queue Flow = 4680 Median lane = 1740 Center lane = 1740 Shoulder lane = 1200 Queue Discharge Flow = : Pre-Queue Flow = 5340 Queue Discharge Flow = 5100 WITHOUT VSL

78 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Analysis Bottleneck Location/Reoccurrence  Include map showing all BN locations for NB and SB (next slide)  Include whether VSL was on/off  Include aerial for popular locations  Need to show no reoccurring and that VSL had no impact on location  Cant compare reoccurring, but still can compare with and without VSL

79 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Analysis Bottleneck Location/Reoccurrence Southbound Legend VSL ON VSL OFF

80 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Analysis Bottleneck Location/Reoccurrence  11 days of detector data with VSL system out of operation (Before Comparison) –October 25, November 1-10 –6 total weekdays of detector data with VSL system off Statistical validness?  Southbound –Isolated bottlenecks on 3 of the days with VSL system off –Isolated bottlenecks on 11 of the days with VSL system on All Non-re-occurring Correlated with median and shoulder lane closures and speed zone o Construction? Maintenance of the system?

81 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Characteristics DayPre-Queue Flow (vphpl) Queue Discharge Flow (vphpl) Change (%) VSL On October 15, 2003 October 16, % Averagexxx VSL Off November 2, 2003 November 3, Averagexxx

82 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN  Consider showing figure to illustrate differences in bottleneck characteristics with and without VSL  Compare to other German, US, Canada freeways

83 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Analysis Shock speed  Show 1 example with and without VSL  Include table listing shock speeds of BN’s –With and without VSL  Are they different? –Speed –Length –Number per day  Oscillation map?  Did VSL dampen shocks –Advise drivers upstream

84 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, :21 15:24 15:34 15:41 15:42 15:47 15:

85 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Analysis  Show corridor oscillation for October 16 to help illustrate what a shock wave is

86 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Shock Summary DayShock Speed (km/hr) Shock Distance (km) VSL On October 15, 2003 October 16, Averagexx VSL Off November 2, 2003 November 3, Averagexx

87 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Analysis – lane harmonization  Show 1 example with and without VSL  Concentrate on pre-queue, during queue  What are trucks doing?  Speeds –Compliance? –What is difference in speeds across all lanes? –Total flow for lanes  What are the differences with and without VSL?

88 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN  Average daily speeds on 5 days before VSL went down, 5 days with VSL down, then 5 after VSL came back on  Measure speeds at 4 stations ( )  Need to label when and what VSL speed limits are

89 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN  Do same thing with daily standard deviation as with average speed

90 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN

91 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN  Summarize speeds at certain traffic states –Freeflow, dense, queue formation, congestion

92 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN

93 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Results  Empirical impacts of VSL system Alteration of key traffic flow parameters o Bottleneck location/reoccurrence o Bottleneck properties (shock speed, pre-queue flow, queue discharge flow) o Lane harmonization (flow/speed) –Contribute to the minimal literature –Potential applications on U.S. freeways Current use in work zones

94 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN  Show tables/figures summarizing results

95 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Complications  Median and shoulder lane closures –Typical on weekdays  60 km/hr speed limit –Construction?  System unstable  Limited ramp data, particularly at A9 and A94 interchanges  High rates of detector failure/drift –Vehicle conservation difficult  Hardshoulder –Difference in capacities

96 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Outline  Introduction  Study Area  Methodology  Analysis  Results  Outlook

97 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Outlook  Continued empirical analysis and comparison with measurements on freeways in the U.S., Canada, and United Kingdom  Improved travel time estimation and forecasting: –Traffic management –Traveler information –Driver assistance systems  Contribute to improved traffic flow models and freeway operational strategies  Opportunity to compare with previous findings using data from German freeways (bottleneck capacity)

98 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Acknowledgements  Dr. Robert Bertini  Dr. Soyoung Ahn  Dr. Klaus Bogenberger, Dr. Georg Lerner, Dr. Hartmut Keller, and the BMW Group  Christian Mayr and Frank Frischeisen of Autobahndirektion Südbayern

99 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Thank you for your attention