The application of SISTM to dynamic control on the M25

Harbord, B

doi:10.1049/ic:19950246

Cited by 3 publications

(3 citation statements)

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“…These reduced speed limits are only introduced when the traffic flows approach the capacity of the mainline and are kept constant for a predefined section of motorway. In the UK, a variable speed limit scheme was introduced in 1995 on the M25 between junction 10 and 15 (Harbord, 1995). These variable speed limits enable the difference between the average mainline speed and the speed limit to be kept as small as possible.…”

Section: Introduction To Throughput Resultsmentioning

confidence: 99%

“…It was selected for a number of reasons including the fact that it has been extensively calibrated and validated with data from a number of UK motorways, it has been used by TRL Ltd on a number of related motorway projects for the HA such as ramp metering and variable speed limits (e.g. Harbord, 1995) and could provide a wide variety of output including parameters such as flow, speed, lane changes and journey times. The program has recently been upgraded by the company QinetiQ to make it more user-friendly, with the option of running the simulation in 3D with a full graphical display (version 6.0).…”

Section: Validation Of Sistmmentioning

confidence: 99%

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Microscopic modelling of motorway diverges

Wall¹,

Hounsell

2020

European Journal of Transport and Infrastructure Research

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This paper describes research looking at the design and operation of motorway diverges using the microscopic computer program SISTM. A diverge is the area of the motorway or other major road where drivers can leave the main carriageway. Low cost measures including the installation of alternative designs (such as the Ghost Island diverge) are assessed which could improve the operation, capacity and driving behaviour at the diverge. Following on from a recent study reviewing the diverging flow-region diagram (used in the UK as a tool to help traffic engineers select the most suitable diverge layout for a particular site with given downstream mainline and diverging flows), it was thought that microscopic models could offer potential benefits in confirming such a choice (particularly in border line situations) as driving behaviour aspects which affect capacity are not catered for in the diagram. SISTM has been used to evaluate existing and alternative diverge layouts in terms of their throughput as well as several other parameters. Modelled and observed data for the speed-flow relationship and the lane distribution of the mainline was compared and differences noted in order that the results could be interpreted correctly. A theoretical comparison of four layouts was carried out; Taper, Parallel, Taper lane drop and Ghost Island diverge. The link between throughput and lane distribution on the mainline before the diverge was also assessed as well as the importance of lane and exit choice. This research presents a summary of some of the key results from the modelling along with a discussion of their accuracy and application. Conclusions and recommendations are made with regard to design implications for diverges along with a list of modelling requirements (essential and desirable) for motorway diverges.

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Section: Introduction To Throughput Resultsmentioning

confidence: 99%

Section: Validation Of Sistmmentioning

confidence: 99%

Microscopic modelling of motorway diverges

Wall¹,

Hounsell

2020

European Journal of Transport and Infrastructure Research

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“…In addition, the log-normal distribution produced slightly better results. (Harbord, 1995); whereas the second is more focused on avoiding or mitigating traffic flow breakdown by reducing the input flow at bottlenecks using VSL (Lenz et al 1999). For this second type of application, the VSL signs are installed upstream of the bottlenecks, with recurring congestion as a way to reduce the speed of the congestion build-up shockwave produced once congestion starts.…”

Section: Heuristics-based Methodsmentioning

confidence: 99%