Institutional Repository
Technical University of Crete
Technical University of Crete
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| URI: | http://purl.tuc.gr/dl/dias/A806A93A-88FD-47B9-B87C-8A2B47E01F7F | ||
| Year | 2018 | ||
| Type of Item | Diploma Work | ||
| License |
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| Bibliographic Citation | Evgenia Stylianopoulou, "Local ramp metering: linear quadratic integral regulator for distant downstream bottlenecks", Diploma Work, School of Production Engineering and Management, Technical University of Crete, Chania, Greece, 2018 https://doi.org/10.26233/heallink.tuc.79032 | ||
| Appears in Collections |
Ramp Metering (RM) is one of the most effective control measures applied in freeways. RM, when driven by an opportune control strategy, alleviates significantly the overall traffic congestion and improves freeway conditions in terms of safety, travel time and reliability. Local ramp metering strategies are implemented for a single ramp and compute the metering rates by taking into account traffic conditions in the vicinity of a ramp. Several real-time ramp metering control algorithms have been developed and proposed in the literature, with ALINEA, an I-type feedback regulator, being the most popular and efficient as it has already been implemented in many field applications. However, there exist cases where bottlenecks with smaller capacity, than the merging area’s, exist further downstream due to, for example, a lane drop, a tunnel, an upgrade, a speed limit area or an uncontrolled downstream on-ramp. In such cases, ALINEA fails to respond satisfactorily and, therefore, other control strategies should be employed, which have been designed so as to use measurements from those further downstream areas where the bottleneck is activated. Towards this direction, this work investigates the application of a new control strategy, specifically a Linear Quadratic Regulator augmented with integral action (LQI), for the local ramp metering control problem when bottlenecks are located many kilometres (up to 5 km) downstream of the metered on-ramp. LQI makes use of measurements all along the area extending from the controllable on-ramp to the bottleneck location, being therefore capable to improve the stability and robustness properties of the control loop. This study investigates various downstream bottleneck scenarios and uses the second-order macroscopic traffic flow model METANET as ground truth for the control application. Simulation results revealed that: i) the proposed methodology handles efficiently the local RM task in case of very distant downstream bottlenecks and, ii) LQI is less sensitive compared to previously proposed control strategies.
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