AbstractLoop detector data for northbound Autobahn 9 (A9) from Munich to Nurnberg, Germany is analyzed using the cumulative curves methodology. The analysis reveals important traffic flow features including bottleneck location and queue discharge rates.

ObjectivesThe objectives of this project are to conduct an empirical analysis of features of traffic dynamics and driver behavior on German and U.S. Highways. An innovative comparison will be made between the behavior of German and U.S. drivers as they approach and pass through freeway bottlenecks. This will provide, for the first time, a direct comparative analysis of German and U.S. freeway data, and will contribute toward a greater understanding of differences in driver behavior in the two countries. In turn, this understanding will allow for improved travel time estimation and forecasting which will lead toward improved traffic management, traveler information and driver assistance systems.

AnalysisA speed contour plot (Figure 2) shows the average speed across all loop detectors on A9 for July 4, 2002. A second speed contour plot (Figure 3) focuses on the time period of 13:00 - 20:00. The detailed contour plot shows a decrease in speed near kilometer marker 520 shortly after 14:00.

The cumulative curves methodology is used to determine the location of the bottleneck. Figure 5 shows the cumulative number of vehicles (N-curve) passing through station 390. In order to observe traffic characteristics this N-curve is re-scaled by a background flow. (Figure 6) This re-scaled cumulative vehicle count curve (N-curve) is the basis for analysis of bottlenecks. Figure 7 shows re-scaled N-curves for stations 390 and 420. The curves are nearly superimposed until 14:16, when a queue reaches station 390, causing a decrease in flow.

The next step is to determine the location of the bottleneck. Re-scaled speed curves (V-curves) are combined with N-curves for each station. Figure 8 shoes that both a drop in speed and flow occurs at station 390 at 14:16. Figure 9 shows a drop in both speed and flow occurs at loop detector station 380 at 14:12. These data indicate that a backward moving queue reaches station 380 at 14:12 and 390 at 14:16. Analyzing the downstream loop detector 350 shows a decrease in flow and an increase in speed at 14:16.(Figure 10) The speed increase and flow decrease indicates that a bottleneck formed upstream of station 350. The bottleneck causes a decrease in downstream flow. As vehicles pass the bottleneck their speed increases, creating the characteristics observed at station 350. The data show that a bottleneck forms between stations 350 and 380.

Next StepsBlah blah blah

AcknowledgementsDr. Klaus Bogenberger and Kristina Laffkas at BMW provided data and assistance throughout the project. November 2006.

Study Area - Northbound Autobahn 9 (A9) from Munich to Nurnberg, Germany

Speed Contour Plot for July 4, 2002

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00

Cu

mu

lati

ve V

eh

icle

Co

un

t (N

-Cu

rve)

390

0

500

1000

1500

2000

2500

3000

3500

13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00

N -

q(o

)t

(q

o =

47

50

)

390

0

500

1000

1500

2000

2500

3000

3500

13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00

N -

q(o

)t

(q

o =

47

50

)

420

390

14:16

19:55

245

14:12 14:13 14:14 14:15 14:16 14:17 14:18 14:19

N(3

90

, t)

- q

(o)t

2605

V(3

90

, t)

- b

(o)t

N(390,t) - q(o)t

V(390,t)-b(o)t

14:16

265

14:08 14:09 14:10 14:11 14:12 14:13 14:14 14:15 14:16

N(3

80,t

)-q

(o)t

2850

V(3

80,t

)-b

(o)t

N(380,t) - q(o)t

V(380,t)-b(o)t

14:12

350

14:14 14:15 14:16 14:17 14:18

N(3

50

,t)

- q

(o)t

3010

V(3

50

,t)

- b

(o)t

N(350,t)-q(o)t

V(350,t)-b(o)t

14:16

14:16

Speed Contour Plot focused on congestion

The circle indicates the first sign of afternoon congestion, shortly after 14:00.

Schematic of Autobahn 9 study area

Cumulative Vehicle Count Curve(N-Curve) at loop detector station 390

Re-scaled N-curves at loop detector station 390

Re-scaled N-curves at loop detector stations 390 and 420

Note: this is a template—please choosedifferent light background colors for your poster

Re-scaled N and V-curves at loop detector station 390

Re-scaled N and V-curves at loop detector station 380

Re-scaled N and V-curves at loop detector station 350

Graphing re-scaled N-curves of loop detector stations 390 and 420 help to identify the precise time and location of the bottleneck. The N-curves are nearly superimposed until 14:16, indicating freely flowing traffic until this point. Congestion reaches station 390 at 14:16, as indicated by a drop in flow and separation of the N-curves.

This graph shows a drop in flow and a corresponding increase in speed at 14:16. This indicates that loop detector station 350 is downstream of the bottleneck.

This graph shows a drop in both speed and flow at loop detector station 380 at 14:12, indicating the time that a backward moving queue reached the station.

This graph shows a drop in both speed and flow at loop detector station 390 at 14:16, indicating the time that a backward moving queue reached the station.

www.its.pdx.edu