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Metoder för att bedöma synavstånd för vägmarkeringar
Swedish National Road and Transport Research Institute, Traffic and road users, Human Factors in the Transport System.ORCID iD: 0000-0002-2061-5817
2018 (Swedish)Report (Other academic)Alternative title
Methods for estimation of the visibility distance of road markings (English)
Abstract [sv]

Studien syftade till att ta fram en metod för att bedöma längsgående vägmarkeringars synavstånd i fordonsbelysning. Metoden ska användas i en kommande studie för att validera en beräkningsmodell, benämnd Visibility, som nyligen har reviderats. Med modellen beräknas vägmarkeringars synavstånd utifrån olika parametrar, bland annat retroreflexion och area.

Studien omfattade en litteraturgenomgång och en serie metodtester i fält. Utifrån litteraturgenomgången och ett fåtal små inledande fälttester togs en kravspecifikation fram. Två metoder, benämnda reflektormetoden respektive kantstolpsmetoden, bedömdes kunna uppfylla kravspecifikationen och de fortsatta testerna inriktades därför på dessa metoder. Reflektormetoden går ut på att vägbanereflektorer placeras intill vägmarkeringen med ett visst avstånd. Bedömningen av synavstånd görs stillastående, genom att ange hur långt vägmarkeringen syns, uttryckt i antal reflektorer. Med kantstolpsmetoden används istället kantstolparnas reflektorer som referenspunkter och vägmarkeringens synavstånd anges därmed i antal kantstolpsreflektorer. Bedömningen görs i fart och observatören bedömer vägmarkeringens synavstånd kontinuerligt över en längre sträcka. Båda metoderna fungerade bra rent praktiskt och upplevdes ge rimliga resultat när de testades var för sig. En jämförelse av metoderna visade dock att de gav väsentligt olika resultat. Orsaken till detta har inte helt klarlagts. Vid ytterligare tester, på väg med intermittenta kantmarkeringar, bedömdes synavstånden genom att räkna antalet synliga markeringar med hjälp av kikare. Denna metod antas ge det mest ”sanna” värdet och den indikerade att kantstolpsmetoden tenderar att överskatta synavstånden, medan reflektormetoden tenderar att underskatta synavstånden något om reflektorerna är placerade nära vägmarkeringen. Att göra bedömningen i stillastående jämfört med i fart hade inte någon väsentlig inverkan på resultatet (synavstånden blev något kortare i fart), men det upplevdes vara svårare att göra en noggrann bedömning i fart.

Abstract [en]

The study aimed at developing a method for estimation of the visibility distance of longitudinal road markings in headlight illumination. The method will be used in a forthcoming study to validate a mathematical model, denoted Visibility, that was recently revised. With this model, the visibility distance of road markings can be calculated from various parameters, such as retroreflectivity and area.

The study included a literature review and a series of tests on public roads. Based on the literature review and a few minor field tests, a requirement specification was prepared. Two methods, denoted the reflector method and the post delineator method, respectively, were assumed to have the potential to fulfil the requirements and were further tested. In the reflector method, reflective road studs are placed along the road marking at a known distance between them. The estimation of visibility distance is done at standstill, by indicating the distance at which the marking is visible, expressed as the number of reflectors. In the post delineator method, the retroreflectors of post delineators are used as reference points instead of road studs and accordingly, the visibility distance is expressed in number of post delineator reflectors. The estimation is done at speed and the observer is continuously estimating the visibility distance while the vehicle is moving. Both methods worked well from a practical point of view and both also seemed to give reasonable results. However, when compared, it was clear that they gave substantially different results. The reason behind this has not been completely clarified. Further tests on a road with broken edge lines, the visibility distances were estimated by calculating the number of visible road markings by using binoculars, which is assumed to give the most “true” estimation. This method indicated that the post delineator method overestimates the visibility distances, while the reflector method may underestimate the visibility distance, if the road studs are placed close to the road marking. Estimating the visibility distance at standstill compared to at speed, did not have a substantial influence on the result, (the visibility distances were somewhat shorter at speed) however, the participants thought it was more difficult to make accurate estimations at speed.

Place, publisher, year, edition, pages
Linköping: Statens väg- och transportforskningsinstitut, 2018. , p. 46
Series
VTI notat ; 24-2018
Keywords [en]
Carriageway marking, Visibility, Visibility distance, Measurement, Calculation, Method, Field (test), Retroreflection, Eye movement
National Category
Infrastructure Engineering
Research subject
30 Road: Highway design, 34 Road: Safety devices
Identifiers
URN: urn:nbn:se:vti:diva-13448OAI: oai:DiVA.org:vti-13448DiVA, id: diva2:1272427
Available from: 2018-12-19 Created: 2018-12-19 Last updated: 2019-06-10Bibliographically approved

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Fors, Carina

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CiteExportLink to record
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Citation style
  • apa
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