1. GLARE & NIGHT TIME DRIVING

2. GLARE… Harsh uncomfortably bright light. It’s a sensation in response to light that can take a number of forms. Results from bright, steady, dazzling light or from shiny surfaces. Can also caused by very bright foreground.

3. GLARE… Or by light reflected by fog or snow. Glare affects both day & night driving performance. Effects of glare on drivers are classified -Discomfort glare -Disability glare

4. Disability Glare Also known as physiological glare. Created by bright light. Its comes from light scattering in the occular media. Reduce driver’s ability to perform visual task. Glaring light scattered in the eye can be expressed as superposition of uniform luminance onto retinal image.

5. Discomfort Glare Bright light Cause discomfort or annoyance Scale of discomfort glare was used by DeBoer. Influenced by 3 factors -location of glare source -luminance of background -luminance & size of glare source

6. HEADLAMP GLARE Vehicle headlamps illuminate the area ahead of vehicle and overhead signs. Essential part of roadway visibility system. Must provide sufficient lighting in the field of view of a driver. Headlamps need to produce and project high light levels.

8. Causes of Headlight Glare Illumination from the glare source Glare angle Back ground luminance Size of the glare source Glare source luminance Driver age Reflective surfaces Glare from mirrors

9. GLARE ON TWO LANE HIGHWAYS.. Lower Light levels Oncoming traffic closer to driver’s line of sight Complex Roadway geometry Less restricted roadway access Less roadway markings Closer proximity of pedestrians

10. Lower Light Levels Visibility of an object depends on overall light levels Pole mounted roadway lighting help to see on unlighted roads Visibility depends on the contrast of an object against its background Glare reduce visibility Can be controlled by higher light levels on road Glare is much larger on unlighted roads

11. Oncoming traffic closer to driver’s line of sight

12. Complex Roadway Geometry

13. LESS RESTRICTED ROADWAY ACCESS Discomfort from headlamp glare increases when visual task is more difficult Chances for hazard along a two lane highway is greater Vehicles enter from variety of locations and directions Not restricted for bicycle travel or pedestrian use Difficult and less safe driving

14. Fewer roadway markings Multi-lane highways are marked with indications for traffic lanes Two-lane highways may not have median lines or nor markings Roadway markings facilitate efficient & safe driving No direct impact on driver Provide visual guidance to a driver

15. CLOSER PROXIMITY OF PEDESTRIANS On two lane highways pedestrians more closer to vehicle traffic Less common on highways but are not restricted Pedestrians themselves are not always easily seen Dark cloths have less reflectance Do not provide much contrast against the roadway pavement Pedestrians themselves often overestimate how visible they are to oncoming traffic

16. COUNTERMEASURES TO CONTROL GLARE -By reducing the illumination -By increasing glare angle -Indirect measures

17. To reduce illumination reaching driver’s eye GLARE SCREENS Placed in the median of roadway Cost effective way to reduce glare Improve safety in temporary work zone Any type of object with certain width and placed at certain spacings that prevent glare

18. Three types-type1,type2,type3 Type1-continous and block light from all angles Eg: earth mounds and concrete barriers Type2-continous screen of an open material opaque to light coming from angle of 0-20 degrees Transparent for beyond 20 degrees

19. Eg: expanded metal mesh, knit polyester fabric and fencing Type3- made up of individual elements that block light from angles of zero to 20 degrees Provide clear visibility beyond 20 degrees Manufactured by individually supported paddles at intervals

21. ROADSIDE PLANTATION Glare can be controlled by planting trees or bushes in the median Position of trees should be fixed Should be sufficiently away from carriage way Tree guard should be prepared to protect the young sapling

22. Prevent glare from sunlight as well as from vehicle headlamps POLARIZED LIGHTING Ordinary light consists of electromagnetic waves which vibrate in all directions When passes through polarizing filter light waves are absorbed Become linearly polarized

23. Can improve visibility by decreasing the amount of light from oncoming headlights. Both vehicles should be equipped with the proper hardware Should have a polarizer and analyser or polarizing filter

24. NIGHT DRIVING GLASSES Used for glare reduction Similar to sunglasses They filter light prior to reaching driver’s eye Improve night time vision and night driving safety

25. To increase the glare angle INCREASE MEDIAN WIDTH AASHTO refers median as a portion of divided highway separating the travelled way for traffic in opposing directions Provide recovery area for out-of-control vehicles Provide stopping area Allow space for speed changes and storage of left turning and U turning vehicles

26. May be depressed or raised Increasing median width decreases the effects of glare from opposing headlights Increasing lateral separation shifts the beam pattern of the opposing vehicle and results in lower intensities of light Reduce both disability and glare

28. INDEPENDENT ALIGNMENT Those with horizontal and vertical alignment Places each roadway at a different elevation Used where there is large median width Eliminates glare entirely

29. Indirect measures to reduce effects of glare ULTRAVIOLET HEADLIGHTS Reduce glare on highways by reducing the need of visible light Improve night time visibility of pedestrians, lane lines, signs and other objects UV radiations when absorbed get converted to longer wave length visible light-FLUORESCENCE It makes objects more easily seen Improve highway safety

30. FIXED ROADWAY LIGHTING Designed according to 3 methods -illuminance -pavement luminance -visibility Reduce night time accidents Improve pedestrians safety Mitigate the effect of glare

31. CONCLUSION Not possible to recommend one counter measure that would eliminate discomfort glare for everyone in all situations. Glare at night can be mitigated by design changes in roadway, automobiles, and vehicles lighting systems and thus improve night vision on highways. No of counter measures can be implemented with minimal cost for glare reduction

32. REFERENCES Avijit Ghosh, Bagui S.K., & Jha S.K. (2004) “highway design considering glare”, Indian highways, vol.33, no.12.pp. December 2004. Ambarish Ghosh & Swapan Kumar “visual systems and glare”, Indian highways, August 2009. Adrain W, “A method for Design of Tunnel Entrance Lighting”, Journal Roads and Streets, pp.125-133. Duncan,D.D. (1996), “Nighttime glare Reduction and Illumination Enhancement ”, Report No. FS-96-037, Johns Hopkins Applied Physics Laboratory, Fleet systems Department, pp.1-35. Hussan,Y.S., Eassa,M. & Abd,A.O.El Halim, (1997), “Modelling for Sight Distance on Three Dimensional Highway Alignment”, Journal of transportation Research Record No.1579, Washington DC

33. THANK YOU...