Transportation

Al-Qadi, I; Loulizi, A; Flintsch, G; Roosevelt, D; Decker, R; Wambold, J; Nixon, W; Fujimoto, A; Fukuhara, T; Watanabe, H; Takeshi, T; Miyazaki, N; Horii, M; Kobayashi, T; Kosugi, K; Sato, T; Mochizuki, S; Sato, A; Morstad, B.W.; Adams, Edward; Bristow, J; McKittrick, Ladean R.

doi:10.1201/9780203024034.pt1

Cited by 4 publications

(4 citation statements)

References 1 publication

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“…In Sweden, traffic is affected when road surface friction is less than 0.4 (Al‐Qadi et al, ). Karlsson () pointed out that road surface friction can decrease close to 0.4, 2 hr after the first occurrence of a hoar frost (see figure 3a in the reference).…”

Section: Methodsmentioning

confidence: 99%

Winter hoar frost conditions on Swedish roads in a warming climate

Huang

et al. 2018

Intl Journal of Climatology

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As one of the most common reasons for slippery roads in wintertime, hoar frost can reduce surface friction and affect traffic safety. The risk of winter road hoar frost is subjected to changes in the warming climate. A better understanding of these changes could lead to improved forecasting of hoar frost risk and provide information to policymakers in making climate adaptation strategies. In this work, the decadal variation in winter road hoar frost risk between 2000 and 2016 in Sweden was examined by using in situ observations from 244 stations in the Swedish Road Weather Information System. Results show that hoar frost risks have decreased in the south of Sweden (south of 59°N), whilst increasing in central Sweden (approximately 59°–65°N). Hoar frost risk tends to increase (decrease) in regions where there is a relatively high (low) mean number of hoar frost risk days. Further analysis indicates that the strengthened winter North Atlantic Oscillation (NAO) over the last few decades, which resulted in warmer and wetter winters in Sweden, is the main cause of the changes. During strong positive NAO winters, the frequency of blocking anticyclones centred to the south‐west of Sweden significantly decreased and led to more warm and moist air from south‐west being transported to Sweden. The reduction in hoar frost risk in the southern part of Sweden is mainly due to an increase in road surface temperature, while the increasing hoar frost risk in central Sweden is dominated by the increase in relative humidity, which favours the occurrence of hoar frost.

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Section: Methodsmentioning

confidence: 99%

Winter hoar frost conditions on Swedish roads in a warming climate

Huang

et al. 2018

Intl Journal of Climatology

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“…For this reason, we simplify our friction outputs by classifying them as either risky or non-risky for the purpose of creating a color-coded risk map. Previous studies have suggested several cutoff values for when friction values are considered unsafe, which can range from 0.3 to 0.5 [34][35][36][37][38]. In this study, we consider three cutoffs within this interval: 0.3, 0.4, and 0.5 to categorize respective driving risks.…”

Section: Binary Systemmentioning

confidence: 99%

Winter Road Friction Estimations via Multi-Source Road Weather Data—A Case Study of Alberta, Canada

Ding

Kwon

2022

Future Transportation

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Road friction has long been recognized as one of the most effective winter road maintenance (WRM) performance measures. It allows WRM personnel to make more informed decisions to improve their services and helps road users make trip-related decisions. In this paper, a machine-learning-based methodological framework was developed to model road friction using inputs from mobile road weather information systems (RWIS) that collect spatially continuous road weather data and road grip. This study also attempts to estimate friction using data from stationary RWIS that are installed far from each other, thereby leaving large areas unmonitored. To fill in the spatial gaps, a kriging interpolator was developed to create a continuous friction map. Slippery road risk levels were classified to provide an overview of road conditions via a risk warning map. The proposed method was evaluated with a selected highway segment in Alberta, Canada. Results show that the models developed herein are highly accurate (93.3%) in estimating friction and identifying dangerous road segments via a color-coded risk map. Given its high performance, the developed model has the potential for large-scale implementation to facilitate more efficient WRM services while also improving the safety and mobility of the traveling public.

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“…A substantial amount of frost has to be deposited to create slippery road conditions (Knollhoff et al, 2003). Karlsson (2001) reported that road surface friction can decrease to 0.4 (below which traffic is adversely affected) (Al-Qadi et al, 2002) 2 hr after the first occurrence of a hoar frost. Therefore, in this study, an occurrence of hoar frost is only recorded if RST is less than T d for at least 2 hr in order to cover all the possibly dangerous conditions caused by hoar frost thoroughly, same as the definition used by Hu et al (2018).…”

Section: Introductionmentioning

confidence: 99%

On the relationship between the risk of hoar frost on roads and a changing climate in Sweden

Gustavsson

et al. 2019

Intl Journal of Climatology

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Hoar frost, one of the most common types of road slipperiness, can reduce road surface friction thereby adversely affecting traffic safety. The two main causes of hoar frost are warm air advection and radiative cooling. This paper investigates the impact of a changing climate on the formation of hoar frost in Sweden during the winter months due to warm air advection and radiative cooling. The analysis is based on in situ observations from 244 stations in the Swedish Road Weather Information System. The results show that in northern Sweden, hoar frost was mainly caused by warm air advection, while radiative cooling was the main cause of hoar frost in southern Sweden. Given the increase in the air temperature over land due to climate change during the period 2000–2016, the relative frequency of hoar frost due to warm air advection has significantly decreased, while the relative frequency of hoar frost due to radiative cooling has significantly increased. Further analysis showed that the weakened temperature gradient between land and ocean, which leads to weakened warm air advection, is the main cause of the changes.

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Transportation

Cited by 4 publications

References 1 publication

Winter hoar frost conditions on Swedish roads in a warming climate

Winter hoar frost conditions on Swedish roads in a warming climate

Winter Road Friction Estimations via Multi-Source Road Weather Data—A Case Study of Alberta, Canada

On the relationship between the risk of hoar frost on roads and a changing climate in Sweden

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