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A data driven approach for automating vehicle activated signs
Högskolan Dalarna, Akademin Industri och samhälle, Mikrodataanalys.ORCID-id: 0000-0001-6526-6537
2016 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Vehicle activated signs (VAS) display a warning message when drivers exceed a particular threshold. VAS are often installed on local roads to display a warning message depending on the speed of the approaching vehicles. VAS are usually powered by electricity; however, battery and solar powered VAS are also commonplace. This thesis investigated devel-opment of an automatic trigger speed of vehicle activated signs in order to influence driver behaviour, the effect of which has been measured in terms of reduced mean speed and low standard deviation. A comprehen-sive understanding of the effectiveness of the trigger speed of the VAS on driver behaviour was established by systematically collecting data. Specif-ically, data on time of day, speed, length and direction of the vehicle have been collected for the purpose, using Doppler radar installed at the road. A data driven calibration method for the radar used in the experiment has also been developed and evaluated.

Results indicate that trigger speed of the VAS had variable effect on driv-ers’ speed at different sites and at different times of the day. It is evident that the optimal trigger speed should be set near the 85th percentile speed, to be able to lower the standard deviation. In the case of battery and solar powered VAS, trigger speeds between the 50th and 85th per-centile offered the best compromise between safety and power consump-tion. Results also indicate that different classes of vehicles report differ-ences in mean speed and standard deviation; on a highway, the mean speed of cars differs slightly from the mean speed of trucks, whereas a significant difference was observed between the classes of vehicles on lo-cal roads. A differential trigger speed was therefore investigated for the sake of completion. A data driven approach using Random forest was found to be appropriate in predicting trigger speeds respective to types of vehicles and traffic conditions. The fact that the predicted trigger speed was found to be consistently around the 85th percentile speed justifies the choice of the automatic model.

Ort, förlag, år, upplaga, sidor
Borlänge: Dalarna University, 2016.
Serie
Dalarna Doctoral Dissertations in Microdata Analysis ; 4
Nyckelord [en]
Optimal trigger speed, vehicle activated sign, mean speed, standard deviation, calibration, driver behaviour, data driven approach, automatic model
Nationell ämneskategori
Data- och informationsvetenskap
Forskningsämne
Komplexa system - mikrodataanalys
Identifikatorer
URN: urn:nbn:se:du-21504ISBN: 978-91-89020-96-2 (tryckt)OAI: oai:DiVA.org:du-21504DiVA, id: diva2:931722
Disputation
2016-06-16, Clas Ohlson, Borlänge, 13:00 (Engelska)
Handledare
Tillgänglig från: 2016-05-30 Skapad: 2016-05-30 Senast uppdaterad: 2019-06-17Bibliografiskt granskad
Delarbeten
1. Review of the effectiveness of vehicle activated signs
Öppna denna publikation i ny flik eller fönster >>Review of the effectiveness of vehicle activated signs
2013 (Engelska)Ingår i: Journal of Transportation Technologies, ISSN 2160-0481, Vol. 3, nr 2, s. 123-130Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

This paper reviews the effectiveness of vehicle activated signs. Vehicle activated signs are being reportedly used in recent years to display dynamic information to road users on an individual basis in order to give a warning or inform about a specific event. Vehicle activated signs are triggered individually by vehicles when a certain criteria is met. An example of such criteria is to trigger a speed limit sign when the driver exceeds a pre-set threshold speed. The preset threshold is usually set to a constant value which is often equal, or relative, to the speed limit on a particular road segment.

This review examines in detail the basis for the configuration of the existing sign types in previous studies and explores the relation between the configuration of the sign and their impact on driver behavior and sign efficiency. Most of previous studies showed that these signs have significant impact on driver behavior, traffic safety and traffic efficiency. In most cases the signs deployed have yielded reductions in mean speeds, in speed variation and in longer headways. However most experiments reported within the area were performed with the signs set to a certain static configuration within applicable conditions. Since some of the aforementioned factors are dynamic in nature, it is felt that the configurations of these signs were thus not carefully considered by previous researchers and there is no clear statement in the previous studies describing the relationship between the trigger value and its consequences under different conditions. Bearing in mind that different designs of vehicle activated signs can give a different impact under certain conditions of road, traffic and weather conditions the current work suggests that variable speed thresholds should be considered instead.

Ort, förlag, år, upplaga, sidor
Irvine, CA: Scientific Research Publishing, 2013
Nyckelord
Vehicle Activated Signs; Variable Message Signs; Threshold Trigger Value; Speed Variation; Traffic Volume; Mean Speed
Nationell ämneskategori
Annan elektroteknik och elektronik
Forskningsämne
Komplexa system - mikrodataanalys, Allmänt Mikrodataaanalys - metod
Identifikatorer
urn:nbn:se:du-11798 (URN)10.4236/jtts.2013.32012 (DOI)
Tillgänglig från: 2013-02-04 Skapad: 2013-02-04 Senast uppdaterad: 2016-05-30Bibliografiskt granskad
2. Data based Calibration System for Radar used by Vehicle Activated Signs
Öppna denna publikation i ny flik eller fönster >>Data based Calibration System for Radar used by Vehicle Activated Signs
2014 (Engelska)Ingår i: Journal of Data Analysis and Information Processing, ISSN 2327-7203, nr 2, s. 11s. 106-116Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

The accurate measurement of a vehicle’s velocity is an essential feature in adaptive vehicle activated sign systems. Since the velocities of the vehicles are acquired from a continuous wave Doppler radar, the data collection becomes challenging. Data accuracy is sensitive to the calibration of the radar on the road. However, clear methodologies for in-field calibration have not been carefully established. The signs are often installed by subjective judgment which results in measurement errors. This paper develops a calibration method based on mining the data collected and matching individual vehicles travelling between two radars. The data was cleaned and prepared in two ways: cleaning and reconstructing. The results showed that the proposed correction factor derived from the cleaned data corresponded well with the experimental factor done on site. In addition, this proposed factor showed superior performance to the one derived from the reconstructed data.

Ort, förlag, år, upplaga, sidor
Scientific Research Publishing, 2014. s. 11
Nyckelord
Vehicle activated signs, Doppler radar, vehicle velocity, experiment, calibration
Nationell ämneskategori
Teknik och teknologier
Forskningsämne
Komplexa system - mikrodataanalys
Identifikatorer
urn:nbn:se:du-16267 (URN)10.4236/jdaip.2014.24013 (DOI)
Projekt
Allmänt Mikrodataaanalys - transporter
Tillgänglig från: 2014-10-27 Skapad: 2014-10-27 Senast uppdaterad: 2016-05-30Bibliografiskt granskad
3. Effectiveness of trigger speed of vehicle-activated signs on mean and standard deviation of speed
Öppna denna publikation i ny flik eller fönster >>Effectiveness of trigger speed of vehicle-activated signs on mean and standard deviation of speed
2016 (Engelska)Ingår i: Journal of Transportation Safety and Security, ISSN 1943-9962, Vol. 8, nr 4, s. 293-309Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Excessive or inappropriate speeds are a key factor in traffic fatalities and crashes. Vehicle-activated signs (VASs) are therefore being extensively used to reduce speeding to increase traffic safety. A VAS is triggered by an individual vehicle when the driver exceeds a speed threshold, otherwise known as trigger speed (TS). The TS is usually set to a constant, normally proportional to the speed limit on the particular segment of road. Decisions concerning the TS largely depend on the local traffic authorities. The primary objective of this article is to help authorities determine the TS that gives an optimal effect on the Mean and Standard Deviation of speed. The data were systematically collected using radar technology whilst varying the TS. The results show that when the applied TS was set near the speed limit, the standard deviation was high. However, the Standard Deviation decreased substantially when the threshold was set to the 85th percentile. This decrease occurred without a significant increase in the mean speed. It is concluded that the optimal threshold speed should approximate the 85th percentile, though VASs should ideally be individually calibrated to the traffic conditions at each site.

Nyckelord
mean speed and standard deviation, trigger speed, vehicle-activated signs
Nationell ämneskategori
Transportteknik och logistik Farkostteknik
Forskningsämne
Komplexa system - mikrodataanalys
Identifikatorer
urn:nbn:se:du-21427 (URN)10.1080/19439962.2014.976690 (DOI)000380365800001 ()2-s2.0-84963593330 (Scopus ID)
Externt samarbete:
Tillgänglig från: 2016-05-09 Skapad: 2016-05-09 Senast uppdaterad: 2016-08-26Bibliografiskt granskad
4. A comparative study between vehicle activated signs and speed indicator devices
Öppna denna publikation i ny flik eller fönster >>A comparative study between vehicle activated signs and speed indicator devices
2017 (Engelska)Ingår i: Transportation Research Procedia, ISSN 2324-9935, E-ISSN 2352-1465, Vol. 22, s. 115-123Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Vehicle activated signs and Speed indicator devices are safety signs used to warn and remind drivers that they are exceeding the speed limit on a particular road segment. This article has analysed and compared such signs with the aim of reporting the most suitable sign for relevant situations. Vehicle speeds were recorded at different test sites and the effects of the signs were studied by analyzing the mean and standard deviation. Preliminary results from the work indicate that both types of signs have variable effects on the mean and standard deviation of speed on a given road segment. Speed indicator devices were relatively more effective than vehicle activated signs on local roads; in contrast their effectivity was only comparable when tested on highways.

Ort, förlag, år, upplaga, sidor
Elsevier, 2017
Nyckelord
vehicle activated signs; speed indicator devices; trigger speed; effect on drivers
Nationell ämneskategori
Data- och informationsvetenskap
Forskningsämne
Komplexa system - mikrodataanalys
Identifikatorer
urn:nbn:se:du-21502 (URN)10.1016/j.trpro.2017.03.017 (DOI)000404633300012 ()2-s2.0-85019409576 (Scopus ID)
Konferens
19th EURO Working Group on Transportation Meeting, EWGT2016, 5-7 September 2016, Istanbul, Turkey
Tillgänglig från: 2016-05-30 Skapad: 2016-05-30 Senast uppdaterad: 2018-01-10Bibliografiskt granskad
5. Triggering Solar-Powered Vehicle Activated Signs using Self Organising Maps with K-means
Öppna denna publikation i ny flik eller fönster >>Triggering Solar-Powered Vehicle Activated Signs using Self Organising Maps with K-means
2014 (Engelska)Konferensbidrag, Publicerat paper (Refereegranskat)
Abstract [en]

Solar-powered vehicle activated signs (VAS) are speed warning signs powered by batteries that are recharged by solar panels. These signs are more desirable than other active warning signs due to the low cost of installation and the minimal maintenance requirements. However, one problem that can affect a solar-powered VAS is the limited power capacity available to keep the sign operational. In order to be able to operate the sign more efficiently, it is proposed that the sign be appropriately triggered by taking into account the prevalent conditions. Triggering the sign depends on many factors such as the prevailing speed limit, road geometry, traffic behaviour, the weather and the number of hours of daylight. The main goal of this paper is therefore to develop an intelligent algorithm that would help optimize the trigger point to achieve the best compromise between speed reduction and power consumption. Data have been systematically collected whereby vehicle speed data were gathered whilst varying the value of the trigger speed threshold. A two stage algorithm is then utilized to extract the trigger speed value. Initially the algorithm employs a Self-Organising Map (SOM), to effectively visualize and explore the properties of the data that is then clustered in the second stage using K-means clustering method. Preliminary results achieved in the study indicate that using a SOM in conjunction with K-means method is found to perform well as opposed to direct clustering of the data by K-means alone. Using a SOM in the current case helped the algorithm determine the number of clusters in the data set, which is a frequent problem in data clustering.

Nyckelord
Solar-powered vehicle activated signs; Self Organising Maps; K-means clustering; Trigger speed
Nationell ämneskategori
Data- och informationsvetenskap
Forskningsämne
Komplexa system - mikrodataanalys
Identifikatorer
urn:nbn:se:du-14133 (URN)
Konferens
The Third International Conference on Intelligent Systems and Applications, INTELLI 2014, June 22 - 26, 2014 - Seville, Spain
Tillgänglig från: 2014-05-25 Skapad: 2014-05-25 Senast uppdaterad: 2018-01-11Bibliografiskt granskad
6. Automatic trigger speed for vehicle activated signs using Adaptive Neuro fuzzy system and Random Forest
Öppna denna publikation i ny flik eller fönster >>Automatic trigger speed for vehicle activated signs using Adaptive Neuro fuzzy system and Random Forest
(Engelska)Ingår i: International Journal on Advances in Intelligent Systems, ISSN 1942-2679, E-ISSN 1942-2679Artikel i tidskrift (Refereegranskat) Submitted
Nationell ämneskategori
Data- och informationsvetenskap
Forskningsämne
Komplexa system - mikrodataanalys
Identifikatorer
urn:nbn:se:du-21503 (URN)
Tillgänglig från: 2016-05-30 Skapad: 2016-05-30 Senast uppdaterad: 2018-01-10Bibliografiskt granskad

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