The capacity of a freeway segment should be measured only when it is an active bottleneck. The properties of flows at active freeway bottlenecks have a bearing on both the definition of capacity and the procedure of capacity analysis. Past studies have examined the flow features at bottlenecks on several freeways in Toronto, Canada, and San Diego, California. This study examined 27 active bottl...

This study aims to determine whether ramp meters increase the capacity of active freeway bottlenecks. The traffic flow characteristics at twenty-seven active bottlenecks in the Twin Cities have been studied for seven weeks without ramp metering and seven weeks with ramp metering. A methodology for systematically identifying active freeway bottlenecks in a metropolitan area is proposed, which re...

Introduction Congestion bottlenecks are severe traffic chokepoints where demand far exceeds available highway capacity. The Federal Highway Administration (FHWA) of the US Department of Transportation states that recurring bottlenecks account for the largest share of road delay in the United States (40%), far exceeding traffic incidents (25%), inclement weather (15%), construction (10%) or othe...

The capacity of a freeway is traditionally considered as a constant value in traffic engineering. In reality, capacities vary according to external conditions such as dry or wet road surfaces, daylight or darkness, and to the prevailing travel purpose of drivers on the freeway. Even under constant external conditions different capacities can be observed on freeways because of variations in driv...

The objective of this study is to determine whether ramp meters increase the capacity of active freeway bottlenecks, and if they do, how. The traffic flow characteristics at twenty-seven active bottlenecks in the Twin Cities have been studied for seven weeks without ramp metering and seven weeks with ramp metering. A series of hypotheses regarding the relationships between ramp metering and the...