1. Abstract Traffic was studied on a thirty kilometer section of freeway north of Frankfurt Am Main, Germany using archived loop detector data. The spatial-temporal characteristics of over eighty bottleneck activations were diagnosed with six days of data. The analysis tools used were curves of cumulative vehicle count and time mean speed versus time. These curves were constructed using data from neighboring freeway loop detectors and were transformed in order to provide the measurement resolution necessary to observe the transitions between freely-flowing and queued conditions and to identify important traffic features.The bottlenecks' locations, pre-queue flows, and mean discharge flows across all lanes and on a lane by lane basis were found to be reproducible from day to day. Further, it is shown that the bottlenecks' mean discharge flow was about 3-5% lower than the mean prevailing flow prior to queue formation when freely flow conditions preceded the activation. Changes in key traffic parameters leading to the formation and dissolution of diverge and merge bottlenecks were investigated and were found to reproducible from day to day. The bottleneck formation triggers for diverge bottleneck activations preceded by freely flowing traffic included high flows across all lanes and high, truck dominated, flows in the right lane just upstream of the bottleneck location. For merge bottleneck activations preceded by freely flowing traffic, reproducible triggers included net lane changing to the left and increases in unmetered on-ramp flow of approximately 25%. Upon bottleneck activation, flow reductions occurring sequentially in time and space marked the passage of backward-moving shocks. Mean shock velocities were in the range of -18 km/h as they traveled upstream from the bottleneck locations. During periods of bottleneck activation, oscillations arose in the upstream congested traffic and propagated upstream at nearly constant speeds. The effects of some bottleneck activations in this study traveled upstream over 20 km, passing through several major interchanges. his research represents an important step towards a greater understanding of how and why freeways bottlenecks arise and some of their characteristics. Together with future empirical studies, this will lead to the development of imprved traffic flow theories and freeway management techniques. Acknowledgements The authors acknowledge the Hessian National Office for Road and Traffic, the Institute for Economics and Traffic at Technical University of Dresden, the ITS Laboratory Team at Portland State University, Department of Civil & Environmental Engineering at PSU and the Department of Civil Engineering & Geomatics at Oregon Institute of Technology. www.its.pdx.edu Analysis of Flow Features in Queued Traffic on a German Freeway Roger V. Lindgren, Oregon Institute of Technology & Dr. Robert Bertini, Portland State University Analysis of Flow Features in Queued Traffic on a German Freeway Roger V. Lindgren, Oregon Institute of Technology & Dr. Robert Bertini, Portland State University Objectives Describe data Identify bottleneck activations Measure of queue discharge features Examine potential bottleneck activation triggers Conclusions and Implications Data: A5 North of Frankfurt Sept. 19, 2001 Inductive loop detectors 1-minute resolution Count and speed in each lane for autos and trucks No fixed auto speed limit Trucks limited to right lane and 80 km/h No ramp metering Good weather 15 bottlenecks analyzed Method Transformed curves of vehicle arrival number vs. time and time-averaged velocity vs. time provide fidelity required to identify key time-dependent traffic features related to active bottlenecks Active bottleneck exists when upstream traffic is queued and downstream traffic unqueued Deactivation occurs with a decrease in flow or when a queue spills back from a downstream bottleneck Time, t @ D22 V(D22,t)-v 0 t' v 0 =5,790 km/h 2 0 20 100 km/h 87 km/h 15:58 15:43 15:46 15:49 15:52 15:55 15:58 16:02 16:05 Shifted Oblique N Curves – A5 Bottleneck Discharge Characteristics Truck Flow and Speed Triggers Conclusions Bottlenecks at predictable locations: Merge and diverge areas Discharge flows: Reproducible across all lanes and lane by lane Nearly constant and should be viewed as the bottlenecks’ capacities “Two capacity” theory was validated: Bottleneck discharge flows lower than pre-activation flows Traffic disturbances: Nearly constant speeds Traveled several km without spreading Diverge bottlenecks triggers: Increased off-ramp flows High pre-queue flows in all lanes with notable truck influence in the right lane Shifted Oblique V Curves – A5