1. 1 Delineation, signing and lighting Hossein Naraghi CE 590 Special Topics Safety March 2003 Time Spent: 8 hrs

2. 2 Delineation Roadway delineation is used to Control placement and movement of vehicles providing information to the driver that identifies the safe and legal limits of the roadway Regulate direction of travel, lane changing and overtaking

3. 3 Delineation (continued) Mark lanes or zones to show turns or parking are permitted, required or restricted Improve lane discipline Particularly during night time driving Aid in identifying potential hazardous situations e.g. obstacles and pedestrian crossing Delineation is of critical importance to the safe and efficient operation of the road system

4. 4 Delineation (continued) Delineation is vital in enabling the driver to locate the vehicle on the roadway and to make navigation and control decision Short range delineation Enables the driver to keep the vehicle within the traffic lane Long range delineation Plan the immediate forward route driving task Needs to be consistent and continuous Not restricted to locations where forward visibility is confusing or critical

5. 5 Delineation (continued) The curve characteristics of direction may need to be assessed up to 9 seconds ahead Detailed tracking data for actual curve negotiation may be required 3 seconds ahead of the curve Delineation is much more critical for older drivers Due to the reduced visual capability, rely to a greater extent on correct delineation of the road ahead

6. 6 Delineation (continued) Delineation devices fall into two groups Pavement markings Roadside device Pavement markings Usually applied using Paint Thermoplastic material Should be highly reflective e.g. use of glass beads mixed into the paint

7. 7 Delineation (continued) Need to be skid-resistant Should be durable Massage they convey must be clear and not led to confusion Massage must be simple and clearly understood There are three categories of pavement markings Longitudinal lines Centerlines, lane lines, edge lines, barrier lines

8. 8 Delineation (continued) Transverse lines Stop lines at intersections Pedestrian crossing lines Word and symbol markings Pavement arrows Painted channelization It is common in UK to use pavement marking to indicate which lane the driver should be in for a particular exit from an intersection

9. 9 Delineation (continued) Zig-zag lines to indicate the approach to pedestrian crossing Yellow box markings to indicate extremities of signalized intersection Speed limit painted on the road surface Limited usefulness of word and symbol marking Adverse condition At night, in the wet, and under heavy traffic Such marking may lead to skidding

10. 10 Delineation (continued) Lane lines and edge lines are particularly helpful in condition of poor visibility At night, in fog or rain Edge lines sometimes provided at the outside edge of the roadway Give marginal advantage in driving performance Main advantage is in short term lane positioning Are as effective on straight alignments as on curves

11. 11 Delineation (continued) Delineation of the outside age of roadway is highly desirable Especially for roads wider than 6 m Evidence shows delineation provides important guidance to motorist When visibility decreases due to adverse weather or night time condition Various studies show safety benefits of edge lines Jackson (1981)reported reduction in total crashes between 13 to 30% and reduction of 37- 42% at night following installation of edge lines

12. 12 Delineation (continued) Tignor (1993) reported a 2% reduction in total crashes and 25% run-of-road crashes in US Another Study in US by Russell indicated that edge line can be justified on two-lane rural roads if there is an average of one non- intersection crash annually per 15.5 miles Other studies questioned the usefulness of edge lines UK county Surveyors’ Society 1989 found that edge line was effective only when it was used at site with specific problem involving loss of control

13. 13 Delineation (continued) Edge lines are usually 4 inch or 6 inches Studies show 6 inches edge lines are more effective especially on curves A study in US by Lum and Hughes (1990) found that Using 8 inches edge lines can be cost-effective where Pavement width exceeds 24 ft Shoulders are unpaved Traffic volumes exceed 2000 vpd

14. 14 Delineation (continued) Raised reflective pavement markers Present a reflective face to oncoming traffic Provide better night time delineation than painted center lines and edge lines especially under adverse weather condition Moses (1985) reported the effect of installation of RRPM’s on sections of rural road in Australia Reduction from 33 to 10 head-on crashes Reduction from 29 to 4 sideswipes crashes

15. 15 Delineation (continued) Rumble devices Grooves or raised ridges placed on roadway to provide a sudden audible and tactile warning to the driver Two types Longitudinal installation to counter driver fatigue or inattention Use on shoulder, edge line, center line Transverse installation to alert drivers to an impending feature Approach to an intersection

16. 16 Delineation (continued) Approach to toll plaza A speed limit change A horizontal curve A lane drop Approach to work zone A number of designs have been used for longitudinal installations Markings are highly reflective Thicker than paints Lines are easily visible above road water on wet days

17. 17 Delineation (continued) Have a longer life than painted lines Raised reflective pavement markers give a tactile sensation when a wheel runs over them which may contribute toward their safety effectiveness Profile edge lines include thermoplastic material applied As continuous extrusion with raised transverse bars As separate transverse bars laid directly on the pavement As a series of parallel grooves passed into the shoulder

18. 18 Delineation (continued) Harwood (1993) cautioned against over- use of rumble devices They may loose their ability to gain the motorist attention One study on effectiveness of rumble strips on the approach to 52 narrow bridges on two highway in Oklahoma shows Over a four year period, the number of run-of- road crashes per million crossing vehicles at the test site fell by 35% on one and 47% on the other Fatal and injury crashes fell by 52% and 56%

19. 19 Delineation (continued) Roadside devices include Continuous devices Guide posts Devices used only at discrete sites Bends Chevrons Bridges Guardrails

20. 20 Delineation (continued) Guideposts and post mounted delineators Guide posts are light weight 3-4 ft high Located 2-10 ft from the edge of the outside lane Should be Low cost Easy to transport Cheap to install and replace Resistant to extreme weather condition Present no safety hazard to road users Present no psychological obstacle to road users

21. 21 Delineation (continued) Guide posts usually have a reflective device attached referred to as a post-mounted delineator Assist long range delineation at night Made from reflective sheeting or from moulded plastic using corner cube principle Should be designed to ensure visibility at long distances, especially at night Be high enough to avoid being soiled by mud

22. 22 Delineation (continued) Some studies reflect the effectiveness of guide posts with reflective delineators 30% reduction in crashes when installed on curves on two lane roads in US 67% reduction in crashes when installed on undivided roads in UK A study on a two-lane rural roads with a 50 mph speed limit found that the reflector posts led to an increase night time average speed of 3 mph and an increase of 20% in crashes

23. 23 Delineation (continued) Chevrons Delineation is critical on curves with radius less than 2000 ft Chevrons commonly used to warn drivers of Sharp bends Medians islands

24. 24 Delineation (continued) Curve alignment markers (CAM) A single post mounted chevron Highly contrasting colors Black on yellow Red on yellow Bhatnagar (1994) developed a relationship between approach speed and curve advisory which indicate that CAMs are suited where there is a difference between these two speeds of about 20 km/h, with CAM’s spaced at:

25. 25 Delineation (continued) 0.12R + 4 meters (for V<80 km/h) 0.08R + 2 meters (for V>80 km/h) Where V is the approach speed (km/h) R is the curve radius (m) Bhatnagar importantly recommends that the use of CAMs should be reserved exclusively for curve delineation and NOT use for Roundabouts Pedestrian refuges Bull nose of guardrails and etc Since such practices will reduce the effectiveness in more critical curve delineation

26. 26 Delineation (continued) Object markers Are applied to hazards such as Bridge abutments Underpass piers Handrails Culverts Trees Poles Bridge piers No known studies have been conducted to determine the effectiveness of specific object markers

27. 27 Delineation (continued) Variable message signs Speed-activated ‘too fast’ signs reduced crashes at sharp curves in Canada A range of dynamic aids which were tested at bridge sites included Flashing beacons Actuated flashing strobes Actuated narrow bridge Oncoming

28. 28 Road signs Road signs are of three types Regulatory signs Speed limits Parking restrictions Direction of traffic flow Turn controls Stop or yield Warning signs Alert the driver to potential hazards ahead Intersections, curves, crests, pedestrian crossings

29. 29 Road signs (continued) Information signs Give drivers information about route direction Destinations Tourist facilities Services Sign maintenance Signs will remain functional and achieve their safety objectives if adequately maintained They fade under sunlight, are subject to accidental and vandal damage

30. 30 Road signs (continued) All signs should be subject to regular maintenance and inspection to ensure They have not become obscured by foliage or other roadside installations Each sign is in good physical condition Each sign is performing its function and conveying its message in day and night Sign’s function is still relevant and necessary, and there is no need to update or replace it All signs and markings are cleaned sufficiently Supporting structures are in sound condition

31. 31 Street lighting Street lighting of appropriate standard contributes to road safety in urban areas It is particularly important where there are pedestrians and cyclists In rural areas, lighting of isolated grade intersections can be a worthwhile safety benefits It should be also noted that the safety benefits of improved lighting can be offset to an extent if lighting posts are poorly located A high proportion of urban single vehicle crashes involve utility poles