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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
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2 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Presentation Outline Introduction Study Area Methodology Analysis Results Outlook
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3 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Presentation Outline Introduction Study Area Methodology Analysis Results Outlook
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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
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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
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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
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7 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Variable Speed Limit: Concept Maintain constant flow
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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)
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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
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10 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Outline Introduction Study Area Methodology Analysis Results Outlook
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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
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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
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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
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14 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Study Area Autobahn 99 (hard shoulder) Lane opened in dense traffic
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15 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Study Area Autobahn 99
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16 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Outline Introduction Study Area Methodology Analysis Results Outlook
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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)
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18 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology A99 Data Summary Detector Data Availability Days with VSLDays without VSL WeekdayWeekendWeekdayWeekend 241075
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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.
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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
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21 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology Transformed Cumulative Curves N(x,t)
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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
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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´
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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 -300 -250 -200 -150 -100 -50 0 N(x,t)-q 0 t´
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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)
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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
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27 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Southbound 945 1250 1357 626 1280 1460 1540 1075 60 70 80 90 110 120 130 140 150 170 190 210 220 232 60 70 80 90 110 120 130 140 150 170 190 210 (MQ) (AQ) 468 930 2250 1650 1110 (m) 290 37 Methodology Time Space Diagram Speed (km/hr)
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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=
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29 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Methodology Flow - Occupancy
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30 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Outline Introduction Study Area Methodology Analysis Results Outlook
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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)
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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
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33 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Speeds Northbound A9 June 27, 2002 630
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34 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Speeds Northbound A9 June 27, 2002 1
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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 380 + Off Ramp -50 50 150 250 350 450 14:4514:5014:5515:0015:0515:1015:1515:2015:2515:3015:3515:4015:4515:50 Time 420 390 380off 630
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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 420 + On Ramp Station 390 Station 380 + Off Ramp Time 630
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37 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN N(x,t)-q 0 t′, q 0 =5170 veh/hr 15:21@ Station 390 15:21@ Station 380 Flow Reduction @380 Bottleneck Activation June 27, 2002 Stations 380–390–420 Time 630
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38 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN 380 15:1515:2015:2515:30 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
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39 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN N(x,t)-q 0 t′, q 0 =5170 veh/hr 15:24@ Station 420 15:21@ Station 390 15:21@ Station 380 Flow Reduction @380 380 55200 55400 55600 15:1515:2015:2515:30 Time 15:21 89 70 V(380,t)-b 0 t′, b 0 =3300 km/hr 2 V(390,t)-b 0 t′, b 0 =4335 km/hr 2 390 98120 98170 98220 15:1515:2015:2515:30 Time 15:21 80 41 420 95010 95060 95110 15:1515:2015:2515:30 Time V(420,t)-b 0 t′, b 0 =4850 km/hr 2 15:24 92 65 Bottleneck Activation June 27, 2002 Stations 380–390–420 Time 630
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40 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 630
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41 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 15:21 15:24 15:34 15:41 15:42 15:47 15:58 630 1
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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 320 + Off-Ramp Station 340 Station 380 + On-Ramp Time @ station 380 Bottleneck Activation June 27, 2002 Stations 320–340–350–380 Time 630
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43 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN N(x,t)-q 0 t′, q 0 =5170 veh/hr 15:21@ Station 380 Flow Reduction @380 Time @ station 380 Bottleneck Activation June 27, 2002 Stations 320–340–350–380 Time 630
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44 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN N(x,t)-q 0 t′, q 0 =5170 veh/hr 15:23@ Station 350 15:27@ Station 320 15:26@ Station 340 15:21@ Station 380 Flow Reduction @380 Time @ station 380 350 40500 40600 40700 15:1515:2015:2515:30 Time 15:23 84 V(350,t)-b 0 t′, b 0 =4200 km/hr 2 340 22320 22370 22420 15:1515:2015:2515:3015:3515:4015:45 Time 15:26 99 97 V(340,t)-b 0 t′, b 0 =5600 km/hr 2 320 19690 19740 19790 15:1515:2015:2515:3015:3515:4015:45 Time 15:27 105 104 V(320,t)-b 0 t′, b 0 =6000 km/hr 2 Bottleneck Activation June 27, 2002 Stations 320–340–350–380 Time 630
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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, 2002 630
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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 19:18 1 630
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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 19:18 1 2 630
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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, 2002 1 2 3 630
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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, 2002 1 2 3 4 630
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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) 0 100 15:0016:0017:0018:0019:00 Time N(x,t)-q 0 t, q 0 =5178 veh/hr 630
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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) 0 100 15:0016:0017:0018:0019:00 Time N(x,t)-q 0 t, q 0 =5178 veh/hr 15:21 17:35 17:40 18:45 19:18 1 630
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52 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 N(380,t) 0 100 15:0016:0017:0018:0019:00 Time N(x,t)-q 0 t, q 0 =5178 veh/hr 15:21 17:35 17:40 18:45 19:18 1 630
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53 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 N(380,t) 0 100 15:0016:0017:0018:0019:00 Time N(x,t)-q 0 t, q 0 =5178 veh/hr 15:21 17:35 17:40 18:45 19:18 5510 vph 5370 vph 1 630
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54 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 N(380,t) 0 100 15:0016:0017:0018:0019:00 Time N(x,t)-q 0 t, q 0 =5178 veh/hr 15:21 17:35 17:40 18:45 19:18 5510 vph 5370 vph 5410 vph 1 4 630
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55 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation Northbound A9 Outflow Summary at 380 630
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56 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation – October 16, 2003
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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 = 4332 2 1 1 2
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58 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Diagnosis 70 60 90 80 110 120 130 140 150 170 190 210 220 232 Station 130 Station 120 Station 110 Station 140 + Off Ramp – On Ramp
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59 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Diagnosis Flow Reduction @ Station 130 Uninterrupted flow between Stations 130 and 140 7:49 @ Station 130 70 60 90 80 110 120 130 140 150 170 190 210 220 232
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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
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61 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Diagnosis
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62 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Diagnosis
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63 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN VSL Dynamics
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64 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN VSL Dynamics posted speed
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65 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN VSL Dynamics Warnings/prohibitions
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66 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN VSL Dynamics text information
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67 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN VSL Dynamics Posted speed vs Measured speed VSL
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68 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Measured speed vs warnings prohibitions Warnings/prohibitions
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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 57-53 Bottleneck shift upstream between 53-47 Bottleneck deactivated Detector speed minus posted speed
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70 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Average trucks speeds +10-20 km/hr above mandatory 80 km/hr Speed Variance: Trucks Detector speed (actual) – Mandatory truck speed (80 km/hr)
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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
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72 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Speed compliance
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73 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN
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74 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN
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75 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Flow – Density Relationship: Detector Station 47/Message Sign AQ 214 1 2 4 3 5 6:14 – 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. 2448 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 57-53 120 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)
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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 = 4332 2 1 1 2 WITH VSL
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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 = 4560 8:53 1 2 3 4 1 2 Pre-Queue Flow = 5340 Queue Discharge Flow = 5100 WITHOUT VSL
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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
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79 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Analysis Bottleneck Location/Reoccurrence Southbound Legend VSL ON VSL OFF
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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?
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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, 200319101610-14% Averagexxx VSL Off November 2, 2003 November 3, 200318331580-0.16 Averagexxx
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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
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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
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84 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Bottleneck Activation June 27, 2002 15:21 15:24 15:34 15:41 15:42 15:47 15:58 630 1
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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
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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, 200319101610 Averagexx VSL Off November 2, 2003 November 3, 200318331580 Averagexx
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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?
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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 (110-140) Need to label when and what VSL speed limits are
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89 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Do same thing with daily standard deviation as with average speed
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90 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN
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91 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Summarize speeds at certain traffic states –Freeflow, dense, queue formation, congestion
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92 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN
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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
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94 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Show tables/figures summarizing results
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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
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96 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Outline Introduction Study Area Methodology Analysis Results Outlook
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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)
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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
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99 ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Thank you for your attention http://www.its.pdx.edu/
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