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
99
Embed
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN Steven Boice Portland State University M.S. Civil Engineering Candidate A Thesis defense presented.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM ON A GERMAN AUTOBAHN
Steven BoicePortland State University
M.S. Civil Engineering Candidate
A Thesis defense presented in the partial fulfillment of the requirements for the degree of
MASTER OF SCIENCEin
CIVIL ENGINEERING
July 28, 2008
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN2
Presentation Outline
Introduction Study Area Methodology Analysis Results Outlook
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN3
Presentation Outline
Introduction Study Area Methodology Analysis Results Outlook
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN4
IntroductionVariable 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
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN5
IntroductionVariable Speed Limit System Speed limits, advisories, regulatory prohibitions presented to drivers via
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
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN7
Variable Speed Limit: Concept
Maintain constant flow
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN8
IntroductionThesis 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)
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN9
IntroductionThesis 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 BMWo Analysis of A9
Rodger Lindgren– Analysis of A5
“Connections” allowed for access to A99 data Opportunity to compare US and German
freeways
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN10
Outline
Introduction Study Area Methodology Analysis Results Outlook
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN11
Study AreaAutobahn 99 - Munich, Germany
A99Study Area
A99 = ¾ ring around City of Munich, Germany
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN12
Study AreaAutobahn 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
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN13
Study AreaA99 Site Facts
Parameter Autobahn 99
Northbound Southbound
Length 15.6 km 16.3 km
Cross section 2-4 lanes 2-4 lanes
Hard shoulder Yes Yes
ADT ? ?
Speed limit Passenger cars - Only when VSL active
Trucks – 80km/hr (all time)
Passenger cars - Only when VSL active
Trucks – 80km/hr (all time)
Ramps 3 off/4 on 4 off/3 on
Mainline detectors (dual loop) 13 14
Ramp detectors (dual loop) 5 6
Detector spacing 320 m – 2,917 m 505 m – 2,250 m
VSL sign gantries 10 12
VSL sign gantry spacing 1,070 m – 2,030 m 663 m – 2,250 m
Flow – Density Relationship: Detector Station 47/Message Sign AQ 214
1
2 4
3
5
N-V Curve
-19600
-19550
-19500
-19450
-19400
-19350
-19300
-19250
-19200
5:50 6:05 6:20 6:35 6:50 7:05 7:20
Time
N(x
,t)-
qo
(t')
q
o =
3800 v
ph
12700
12900
13100
13300
13500
13700
13900
V(x
,t)-
bo
(t')
b
o =
3900 k
m/h
r2
Det 47 N Det 47 V
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 vph3728 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/hr100 km/hr80 km/hr60 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)
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN76
Sou
thbo
und
9:53
8:029:44
8:18
8:25
9:29
9:28
9:497:56
8:55
10 km/hr
Pre-queue Flow = 4630 Median lane = 1848 Center lane = 1835 Shoulder lane = 948Queue Discharge Flow = 4134
Queue Discharge Flow = 4332
2
1
1 2
WITH VSL
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN77
8:34
9:05
8:13
8:07
8:02
7:56
8:43
8:49 9:008:27
8:54
7:48
7:278:33
9:41
8:26
8:34 8:57 9:16
8:53
8:18 8:21
9:189:078:27 8:378:22
8:41
7:47 8:00
9:168:38 8:50
9:32
7:358:10
15 km/hr 20 km/hr
5 km/hr
Pre-Queue Flow = 4680 Median lane = 1740 Center lane = 1740 Shoulder lane = 1200Queue Discharge Flow = 4560
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
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN79
AnalysisBottleneck Location/Reoccurrence
Southbound
Legend
VSL ON VSL OFF
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN80
AnalysisBottleneck 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?
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN81
Bottleneck Characteristics
Day Pre-Queue Flow (vphpl)
Queue Discharge Flow (vphpl)
Change (%)
VSL On
October 15, 2003
October 16, 2003 1910 1610 -14%
Average x x x
VSL Off
November 2, 2003
November 3, 2003 1833 1580 -0.16
Average x x x
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN82
Consider showing figure to illustrate differences in bottleneck characteristics with and without VSL
Compare to other German, US, Canada freeways
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN83
AnalysisShock 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
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN84
Bottleneck Activation June 27, 2002
15:21
15:24
15:34
15:4115:42
15:47
15:58 630
1
540
29400
29600
29800
15:15 15:20 15:25 15:30 15:35 15:40 15:45
Time
V(5
40,
t)-b
0t′,
b0=
4550
km
/hr2
15:349739
560
36420
36520
36620
15:30 15:35 15:40 15:45 15:50 15:55 16:00
Time
V(5
60,
t)-b
0t′,
b0=
3550
km
/hr2
15:4183 43
580
34180
34280
34380
34480
15:30 15:35 15:40 15:45 15:50 15:55 16:00
Time
V(5
80,
t)-b
0t′,
b0=
3650
km
/hr2
15:4287 43
600
32400
32500
32600
32700
15:30 15:35 15:40 15:45 15:50 15:55 16:00
Time
630
41450
41650
41850
15:45 15:50 15:55 16:00 16:05 16:10 16:15
Time
V(6
00,
t)-b
0t′
, b0=
3450
km
/hr2
15:47
72 38
V(6
30,
t)-b
0t′
, b0=
3100
km
/hr2
15:5893 20
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN85
Analysis
Show corridor oscillation for October 16 to help illustrate what a shock wave is
-200
0
200
400
600
800
1000
1200
1400
7:00 7:14 7:28 7:43 7:57 8:12 8:26 8:40 8:55
det. 60
det. 70
det. 80
det. 90
det. 110
det. 120
det. 130
det. 140
det. 150
det. 170
det. 190
det. 210
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN86
Shock Summary
Day Shock Speed (km/hr)
Shock Distance (km)
VSL On
October 15, 2003
October 16, 2003 1910 1610
Average x x
VSL Off
November 2, 2003
November 3, 2003 1833 1580
Average x x
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN87
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?
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN88
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
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN89
Do same thing with daily standard deviation as with average speed
Station 12010.16 & 11.3
0
10
20
30
40
50
60
70
80
1:00
2:00
3:00
4:00
5:00
6:00
7:00
8:00
9:00
10:0
011
:00
12:0
013
:00
14:0
015
:00
16:0
017
:00
18:0
019
:00
20:0
021
:00
22:0
023
:00
0:00
Time
Sta
nd
ard
Dev
iati
on
Sp
eed
(km
/hr)
No VSL VSL
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN90
Station 12010.16 & 11.3
0
10
20
30
40
50
60
70
80
1:00
2:00
3:00
4:00
5:00
6:00
7:00
8:00
9:00
10:0
011
:00
12:0
013
:00
14:0
015
:00
16:0
017
:00
18:0
019
:00
20:0
021
:00
22:0
023
:00
0:00
Time
Sta
nd
ard
De
via
tio
n S
pe
ed (
km
/hr)
No VSL VSL 60 VSL 80 VSL Off
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN91
Summarize speeds at certain traffic states– Freeflow, dense, queue formation, congestion
Station 12010.16.03 & 11.3.03
8276 76 73
121115
10294
0
20
40
60
80
100
120
140
FreeFlow Dense Queue Formation Congested
Ave
rag
e S
pee
d (
km/h
r)
0
2
4
6
8
10
12
14
16
18
Sta
nd
ard
Dev
iati
on
Sp
eed
(k
m/h
r)
VSL Avg No VSL Avg VSL Std No VSL Std
Station 12010.16.03 & 11.3.03
42
65
8594
26
64
86
97
0
20
40
60
80
100
120
FreeFlow Dense Queue Formation Congested
Ave
rag
e F
low
(vp
m)
0
2
4
6
8
10
12
14
16
18
Sta
nd
ard
Dev
iati
on
Flo
w (
vpm
)
VSL Avg No VSL Avg VSL Std No VSL Std
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN92
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN93
Results
Empirical impacts of VSL system• Alteration of key traffic flow parameters
o Bottleneck location/reoccurrenceo 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
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN94
Show tables/figures summarizing results
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN95
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
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN96
Outline
Introduction Study Area Methodology Analysis Results Outlook
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN97
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)
ANALYSIS OF VARIABLE SPEED LIMIT SYSTEM
ON A GERMAN AUTOBAHN98
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