The objective of this study is to clarify the degree to which slippery winter road conditions affect saturation flow rates at urban signalized intersections. For that purpose, in addition to the usual traffic study and visual classification of road conditions, skid resistance values between tire and road surface were measured as an indicator of road slipperiness with a measuring device equipped vehicle. Skid resistance indicates friction resistance between a tire and the road surface, and is expressed by Skid Number. A field survey showed the wide variation of road surface conditions in winter. As a result, it was shown that the decrease of winter saturation flow rates was about 20 per cent compared with the observed non-winter saturation flow rates and was at the most 30 per cent compared with the basic saturation flow rate which is 2000 pcplphg. PCE values for a heavy vehicle were estimated and heavy vehicle adjustment factors were computed using them. (A)
Samenvatting