Sight TRB presentation

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Dutch Ministry of Transport, Public Works and
Water Management
Civil Engineering Division Road Design
Department Patrick
Broeren Evaluating Sight Distances A
Practical Tool for Highway Design
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Contents presentation

• Introduction
• Sight Distances
• Application Zicht
• Case Study
• Further Developments
• Conclusion

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Introduction

• Driving behavior based on visual perception of a
  road
• For traffic flow and safety reasons, drivers need
  to see a minimum length of the road ahead
• Sight distance on a road should be sufficient to
  carry out a necessary maneuver before reaching a
  stionary object

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Sight distances

• Dutch design guidelines (ROA)
• Stopping sight distance (queues)
• Maneuver sight distance (small object)
• Road view sight distance (edge line marking)
• Passing sight distance (overtaking)
• Local sight distances (intersections, traffic
  signs)

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Sight distances

• International variation in sight distance
  calculations
• Important sight distance parameters
• (design) speed
• eye height
• perception reaction time
• action time (braking, overtaking)
• deceleration rate (stopping sight)

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Sight distances

• Stopping sight distance, design speed 120 km/h

7
Sight distances

• Check visibility object in 3D road design

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Application Zicht

• Dutch Ministry of Transport and NedGraphics have
  developed a new software application for
  calculating sight distances
• Zicht (Dutch for sight) is suitable for
• Practical use in complex road design
• Research on the effects of sight distance
  parameter variations

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Application Zicht

• Calculations based on visualization techniques
• Visibility object is checked with ray-trace
  module
• Module projects rays from observation point
  driver onto sight distance object (obstacle,
  taillight, marking)
• What do you need ?
• AutoCAD 2000 (Map, LDD, 2000i)
• 3D road and terrain model consisting of 3D-faces
  and polylines

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• Ray-trace calculations

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Design speed
Minimum sight distances
Eye Height
Calculation Accuracy
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Table
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Minimum sight distance
Present sight distance
Graph
station
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Perspective views
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Case study

• Crossing of Highway A4 and High Speed Rail Link
  Amsterdam Paris
• Alignement A4 checked on sight distances and
  drivers view with Zicht

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• First design
• Present maneuver sight distances not sufficient
• Section of 100 m, sight distance deficit max. 45
  m
• Second design
• Alignment changed gt design meets guidelines

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Further developments

• International, AASHTO-version of Zicht
• Extending the calculation model with passing
  sight distances
• More options for preparation of the road and
  terrain model
• Animation tool

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Conclusion

• With modern CAD-tools, road designers can check
  sight distances in 3D
• Higher quality of design
• Research purposes
• Information Zicht www.sightlines.nl
• Demo meet me after this session !
• Questions, remarks, suggestions ????