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The continuous line continued.... A research to the effect of a continuous line at a highway access

Leferink, Bart (2013) The continuous line continued.... A research to the effect of a continuous line at a highway access.

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Abstract:Congestion is a daily phenomenon at Dutch highways. One of the main causes are merges of onramps and highways. Only little research has been conducted to increase the highway performance at a merge. This research aims to evaluate to what extent a continuous line in the pre-merging section of the highway could increase the highway performance. This is done by performing a single case study at Hengelo-Zuid in combination with using a traffic simulation model. A literature review shows the relation between traffic characteristics around a merge. At a macroscopic scale, these are capacity distributions, congestion, traffic flows and shock waves. At a microscopic scale, also headways, lane distributions and lane changing play an important role. Ramp metering is usually used to control on-ramp flows and to prevent highway congestion. The study area at Hengelo-Zuid consists of a two-lane main carriageway. This area is analysed with data gathered from detection loops and road side video measurements. Data from the adjacent road network and traffic flow predictions for 2020 are used to determine effects at the wider network for now and the near future. In the study area, a capacity drop of 19% is observed. Congestion takes on average 30 minutes, with highway and on-ramp delays up to respectively three and six minutes. Non-congested and congested traffic patterns are analysed. Cooperative lane changing is observed, which influences the lane distribution significantly. The highway access at Hengelo-Zuid is modelled with the simulation software Fosim. Here, the capacity value is used as main performance indicator. The model is calibrated and validated with the observed microscopic and macroscopic traffic flow characteristics to improve the correctness of capacity calculations. The effect of the continuous line is evaluated for three different on-ramp flows: 1) a signalised onramp flow; 2) a random on-ramp flow; and 3) a metered on-ramp flow (with Rijkswaterstaatalgorithm). All these on-ramp flows are theoretically and practically relevant. The conclusion is that a continuous line can increase the capacity slightly but significantly. Though, for high signalised and metered on-ramp flows, this increase is constrained by negative effects at lane one, which is the left lane from the highway. For these situations, a shorter version of the line is preferable. The capacity increase is due to an increased share of vehicles at lane one. Aim of the line is to reach an optimal lane distribution. The amount of lane changes does not increase with a line, neither before the merge, nor after the merge. With a line, the ramp meter release rate could be increased significantly without increasing the congestion probability. In Hengelo-Zuid, the continuous line can reduce the congestion probability. The reduction of highway congestion duration is estimated to be ten minutes; reduction in on-ramp delay is 1.5 minutes. The results imply that a continuous line could reduce congestion on several places in The Netherlands.
Item Type:Essay (Master)
USE System Engineering BV
Arcadis Nederland BV
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
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