Evaluating Sight Distancespublicaties.minienm.nl/download-bijlage/113427/264786-fulltext-eng… ·...
Transcript of Evaluating Sight Distancespublicaties.minienm.nl/download-bijlage/113427/264786-fulltext-eng… ·...
Civil Engineering DivisionRoad Design Department
Patrick Broeren
Evaluating Sight DistancesA Practical Tool for Highway Design
Dutch Ministry of Transport, Public Works and Water Management
TRB 2
Contents presentation
1. Introduction
2. Sight Distances
3. Application Zicht
4. Case Study
5. Further Developments
6. Conclusion
TRB 3
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
TRB 4
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)
TRB 5
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)
TRB 6
Sight distances
• Stopping sight distance, design speed = 120 km/h
0
50
100
150
200
250
300
Switzerland
Japan
Italy
Canada
Australia
US
Germany
Netherlands
UK
TRB 7
Sight distances
• Check visibility object in 3D road design
TRB 8
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
TRB 9
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
TRB 10
Ray-trace calculations
TRB 11
Design speed
Minimum sight distances
Eye Height
CalculationAccuracy
TRB 12
Table
TRB 13
Graphstation
Presentsight distance
Minimumsight distance
TRB 14
Perspective views
TRB 15
Case study
• Crossing of Highway A4 and High Speed Rail Link Amsterdam – Paris
• Alignement A4 checked on sight distances and drivers view with Zicht
TRB 16
First design:
• Present maneuver sight distances not sufficient
• Section of 100 m, sight distance deficit max. 45 m
Second design:
• Alignment changed => design meets guidelines
TRB 17
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
TRB 18
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 ????