Delineation, signing and lighting

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

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

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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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