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Screening Hydroplaning Risk Area By Hsd Data
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Screening Hydroplaning Risk Area By Hsd Data

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According to road safety reports from various RCAs, about 30%-40% of road crashes occurred in wet conditions and among these wet road crashes, at least 50% of the drivers experienced loss-of-control ...

According to road safety reports from various RCAs, about 30%-40% of road crashes occurred in wet conditions and among these wet road crashes, at least 50% of the drivers experienced loss-of-control of the vehicle in a partial or full degree, an indication of hydroplaning, which often resulted in serious injury or even fatal accidents. Unfortunately, risk of hydroplaning is often only considered in the design stage of roads and highways by providing sufficient drainage and proper selection of surface materials. During the operation and maintenance of roads and highways, there is still no direct and practical method to quantify hydroplaning risk for existing roads and highways.

Although several vehicle, roadway, and environmental factors affect the probability of hydroplaning, a general rule of thumb for highways is that hydroplaning can be expected for speeds above 70kph where water ponds to a depth of 2.5mm or greater over a distance of 10m or greater. In other words, for any set of driver inputs, tyre conditions and surfacing material, hydroplaning is only a function of water depth and vehicle speed. In this paper, a methodology for identifying and screening of hydroplaning risk area through analyzing the pavement transverse and longitudinal profile measurement from HSD survey will be introduced. Examples will be given to demonstrate that it will be a useful tool for road controlling agencies to evaluate the risk of hydroplaning for their road networks and to plan and carry out necessary maintenance actions to provide a safer road network for the public.

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  • Thank you, Mr. Chairman, for your kind introduction. Good morning, ladies and gentlemen! Today, the topic of my presentation is Screening Hydroplaning Risk Area by HSD Data. Without further ado, let’s let at the introduction.
  • According to road safety reports from various road controlling authorities in New Zealand, about 30%-40% of road crashes occurred in wet conditions. To reduce the number of crashes in wet weather, a lot of effort in the last 20 years has been put into studying and improving the skid resistance performance of the road pavement surfacing by the selection of polish resistant surfacing aggregates and the appropriate maintenance methods.
  • However, as another type of wet weather risk, hydroplaning, is often only considered and handled in the design phase of road and highway engineering by providing sufficient drainage and proper selection of surface materials. During the operation and maintenance of roads and highways, there is still no direct and practical method to quantify hydroplaning risk on existing roads and highways. Usually, hydroplaning risk is considered as part of the skid resistance problem. However, hydroplaning is totally different from skidding in its mechanism and pavement with good skid resistance performance does not guarantee that it prevents hydroplaning risk.
  • To understand the mechanism and risk of hydroplaning, let’s look at a short movie first. From this movie, we get that for any set of driver inputs, tyre conditions and surfacing material, hydroplaning is only a function of water depth and vehicle speed. A general rule of thumb for highways is that hydroplaning can be expected for speeds above 70kph where water ponds to a depth of 2.5mm or greater over a distance of 10m or greater.
  • Pavement transverse profile is normally measured by HSD equipment such as laser profiler to calculate rut depth in the wheelpath. On the other side, water depth can be measured perpendicular to the water surface as the largest of the measured depths from a mean transverse profile. In this research, a methodology for identifying and screening of hydroplaning risk area through calculation of water depth from pavement profile measurement will be introduced.
  • Since both hydroplaning and traffic safety are very complex topic. Certain assumptions are necessary to solve the problem. The assumptions made in this study are Rainfall intensity and duration is enough to cause the maximum possible water depth on the road surface; Surface drainage is conducted on transverse direction only through the crossfall of road;The influence of tyre characteristics such as tread pattern and depth is ignored; The risk of hydroplaning exposed to all kinds of vehicles and drivers with the same travel speed by the road is similar.
  • With the assumptions mentioned above, the methodology developed for this problem is as follows: First, Compute the maximum water depth for each transverse profile measurement along the road section. Next, Calculate the minimum water depth that can cause hydroplaning of vehicle at specific travel speed. Finally, Find the hydroplaning risk area of road section for those areas with the actual maximum water depth exceeding the minimum water depth that can cause the hydroplaning of vehicle at specific travel speed with a length more than 10m.
  • The equation adopted in this research for the calculation of minimum water depth that can cause the hydroplaning of vehicle at certain speed is as follows. Where, WDmin is the minimum water depth in mm that can cause the hydroplaning of vehicle and S is the vehicle speed in kph. By using the above equation, the minimum water depth that cause hydroplaning of vehicle was calculated for a series of speeds as shown following table shown in this slide.

Screening Hydroplaning Risk Area By Hsd Data Screening Hydroplaning Risk Area By Hsd Data Presentation Transcript

  • Screening Hydroplaning Risk Area by HSD Data Dr Wei Liu Senior Engineer Fugro PMS Ltd
  • Introduction
    • According to road safety reports from various road controlling authorities in New Zealand, about 30%-40% of road crashes occurred in wet conditions.
    • To reduce the number of crashes in wet weather, a lot of effort in the last 20 years has been put into studying and improving the skid resistance performance of the road pavement surfacing by the selection of polish resistant surfacing aggregates and the appropriate maintenance methods.
  • Introduction
    • However, as another type of wet weather risk, hydroplaning, is often only considered and handled in the design phase of road and highway engineering by providing sufficient drainage and proper selection of surface materials.
    • During the operation and maintenance of roads and highways, there is still no direct and practical method to quantify hydroplaning risk on existing roads and highways.
    • Moreover, w hen hydroplaning occurs (which can be either full or partial hydroplaning), it often results in a serious injury or fatal accident.
  • Introduction
    • For any set of driver inputs, tyre conditions and surfacing material, hydroplaning is only a function of water depth and vehicle speed.
    • A general rule of thumb for highways is that hydroplaning can be expected for speeds above 70kph where water ponds to a depth of 2.5mm or greater over a distance of 10m or greater.
  • Introduction
    • Pavement transverse profile is normally measured by HSD equipment such as laser profiler to calculate rut depth in the wheelpath.
    • On the other side, water depth can be measured perpendicular to the water surface as the largest of the measured depths from a mean transverse profile.
    • In this research, a methodology for identifying and screening of hydroplaning risk area through calculation of water depth from pavement profile measurement will be introduced.
    Transverse Profile Water Depth
  • Methodology
    • Assumptions
      • Rainfall intensity and duration is enough to cause the maximum possible water depth on the road surface.
      • Surface drainage is conducted on transverse direction only through the crossfall of road.
      • The influence of tyre characteristics such as tread pattern and depth is ignored.
      • The risk of hydroplaning exposed to all kinds of vehicles and drivers with the same travel speed by the road is similar.
  • Methodology
    • Methodology
      • Compute the maximum water depth for each transverse profile measurement along the road section.
      • Calculate the minimum water depth that can cause hydroplaning of vehicle at specific travel speed
      • Find the hydroplaning risk area of road section for those areas with the actual maximum water depth exceeding the minimum water depth that can cause the hydroplaning of vehicle at specific travel speed with a length more than 10m.
  • Methodology
    • Minimum water depth that can cause the hydroplaning of vehicle:
    • Where, WDmin is the minimum water depth in mm that can cause the hydroplaning of vehicle and S is the vehicle speed in kph.
    0.44 120 0.61 110 0.89 100 1.33 90 2.10 80 3.51 70 6.36 60 12.87 50 WDmin(mm) Speed (kph)
  • Implementation Example
    • A road section of 5.7km long from SH003/RS0057 was selected to carry out the hydroplaning risk analysis.
    • This section was selected because there were 15 accidents happened in this section of road under wet surface condition during the last 5 years.
  • Implementation Example
    • Maximum water depth calculation results for decreasing lane of SH003/RS057
  • Implementation Example
    • Maximum water depth calculation results for increasing lane of SH003/RS057
  • Implementation Example
    • Hydroplaning risk area identification results for decreasing lane of SH003/RS057
      • Analysis speed: 100 km/h
      • Minimum water depth for hydroplaning: 0.89mm
      • Minimum length of water pond: 10m
    32 5488 5456 D 20 100 27 5380 5353 D 19 100 43 4986 4943 D 18 100 12 4917 4905 D 17 100 10 4868 4858 D 16 100 27 4783 4756 D 14 100 28 4736 4708 D 14 100 42 4508 4466 D 13 100 34 4072 4038 D 12 100 43 3800 3757 D 11 100 68 3499 3431 D 10 100 145 3408 3263 D 9 100 22 3077 3055 D 8 100 36 2911 2875 D 7 100 28 2774 2746 D 6 100 47 2570 2523 D 5 100 38 861 823 D 4 100 41 709 668 D 3 100 31 576 545 D 2 100 18 463 445 D 1 100 Length (m) End (m) Start (m) Direction Risk Area No Analysis Speed
  • Implementation Example
    • Hydroplaning risk area identification results for increasing lane of SH003/RS057
      • Analysis speed: 100 km/h
      • Minimum water depth for hydroplaning: 0.89mm
      • Minimum length of water pond: 10m
    Length (m) End (m) Start (m) Direction Risk Area No Analysis Speed 25 5655 5630 I 19 100 37 5304 5267 I 18 100 28 5238 5210 I 17 100 39 5182 5143 I 16 100 36 5137 5101 I 15 100 17 4416 4399 I 14 100 12 4219 4207 I 13 100 14 3638 3624 I 12 100 12 3126 3114 I 11 100 13 2463 2450 I 10 100 43 2269 2226 I 9 100 35 2035 2000 I 8 100 34 1736 1702 I 7 100 30 1585 1555 I 6 100 18 1544 1526 I 5 100 10 1464 1454 I 4 100 54 897 843 I 3 100 11 832 821 I 2 100 22 728 706 I 1 100
  • Summary and Conclusion
    • A computer based analysis methodology and procedure for screening hydroplaning risk on the network level has been developed.
    • This procedure takes the pavement profile data from HSD survey as input and calculates the maximum water depth occurring on the road.
    • The maximum water depth results were then used to compare the minimum water depth that can cause the hydroplaning of vehicle at a specific speed to identify the potential hydroplaning risk area.
    • An implementation example has demonstrated that the proposed methodology can provide meaningful results by comparing the wet accident records from CAS database.
    • It is recommended that the proposed method should be applied as a supplement to the skid resistance method for the selection of safety improvement project.
  • Thank you! If any question or comment, please feel free to contact us [email_address] [email_address] Phone: 07-8470499