1. Chapter 3: Traffic Control Devices

2. Overview Regulations Principles Signs Regulatory Warning Guide
Pavement Markings
Traffic signals covered under INTERSECTIONS in Chapter 6

3. Manual on Uniform Traffic Control Devices (MUTCD)
National standard for all traffic control devices on public roads
Jurisdictions with own MUTCDs or supplements shall be in substantial conformance with those endorsed by FHWA
Responsibility of design, placement, operation, maintenance, and uniformity of traffic control devices rests with public agency
MUTCD describes application of traffic control devices – it is not a legal requirement for installation
Purpose of traffic control devices is to promote highway safety and efficiency by providing for orderly movement of all road users. MUTCD provides uniformity in size, shape, color, composition, lighting or retroreflection, and contrast to command attention to devices. Legibility and size combine with placement to permit adequate time for response by road users. Sign size, shape, color, and simplicity combine to produce a clear meaning. Uniformity, size, legibility, and reasonableness of the message combine to command respect by road users.

4. Traffic Control Device Principles
Fulfill a need
Command attention
Command respect
Have a simple, clear meaning
Allow adequate time for response
The principles of traffic control devices are listed. To be effective, all of the five basic requirements should be met. It is important that the five principles be given primary consideration in the selection and application of each device.
Design, placement, operation, maintenance, and uniformity are aspects that should be carefully considered in order to maximize the ability of a traffic control device to meet the five principles listed. Vehicle speed should also be considered in the design, operation, placement, and location of traffic control devices. Proper use (and uniformity) provides reasonable and prudent drivers with the information necessary to operate safety and lawfully on public roads.

5. Sign Types Regulatory Warning Guide
Regulatory signs tell road users about traffic regulations and laws. Road departments use them to control vehicle and pedestrian movements. Examples include STOP signs, NO PARKING signs, and speed limit signs.
Warning signs tell road users to be cautious because of a condition on or near the roadway. Warning signs are especially helpful to drivers who are not familiar with the road. Use warning signs only where needed because overuse can lead to disrespect for all warning signs, which reduces their effectiveness.
Guide and information signs provide navigation and service information to drivers. These signs include route markers, destination signs, and information signs. They have green, blue, or brown backgrounds and white letters. Guide signs in work zones should be orange with black lettering.
By giving information to drivers when they need it, we can reduce the unpredictable behavior of drivers who suddenly realize they are going the wrong way or just missed a turn.

6. Regulatory Signs Used to control actions of road users
Require law, ordinance, or regulation
Authority varies with municipality
Many regulations are unenforceable unless the proper signs are posted. Regulatory signs remind drivers of statutory rules, but statutory rules do not need signs to be enforceable. For example, we know it is illegal to park a vehicle in front of a fire hydrant, whether or not a sign prohibits it. To prohibit parking where it would otherwise be legal requires no parking regulations and signs.
The Uniform Vehicle Code covers use of traffic regulations. Appropriate enabling ordinances or legislation must be in place before a regulatory sign is installed. To learn more about the extent of your agency’s authority, refer to your jurisdiction’s vehicle code.
Most regulatory signs are rectangular and taller than they are wide. Exceptions include STOP and YIELD signs. White, black, and red are used for regulatory signs.
Regulatory signs can promote smooth, orderly traffic flow, but only when they are properly used and enforced. When used incorrectly, they can cause more problems than they solve. For example, unnecessary STOP signs cause needless air and noise pollution. Drivers often disobey regulations they think are unnecessary. These road users may intentionally disregard what they believe are irrelevant or unrealistic traffic regulations. Other roadway users may expect them to obey the regulation, and act accordingly, with potentially fatal results. For example, a pedestrian may assume an approaching driver will stop at the STOP sign. A serious injury could occur if the driver does not stop.

7. Warning Signs Warn of conditions on or near road
Overuse reduces effectiveness
As you decide whether a warning sign is needed, consider whether the hazard can be removed. If removing the hazard is impossible or not cost-effective, install the warning sign. If you plan to remove the hazard eventually, install a sign to warn traffic of the condition until you can remove the hazard.
Warning signs are usually diamond-shaped, with black text or symbols on a yellow background. Road work warning signs should have orange backgrounds. An exception is the railroad crossing sign. It is always round and always has a yellow background, even when used in a work zone.
The fluorescent yellow-green background is optional on certain warning signs, including pedestrian, bicyclist, playground, school bus, and school signs. Fluorescent yellow-green signs are gaining popularity because they are more easily seen in bad weather.

8. Warning Sign Conditions
Condition A
Speed reduction or lane change
Condition B
Deceleration to advisory speed
The MUTCD publishes guidelines for advance placement of warning signs. The guidelines are based on two conditions. Condition A is for a speed reduction or lane changing in heavy traffic. Typical conditions are locations where road users must use extra time to adjust speed and change lanes in heavy traffic because of a complex situation. Examples are Merge or Right Lane Ends (typical driver perception-reaction time is 14.0 to 14.5 seconds.
Condition B is for deceleration to the listed advisory speed for the condition. Typical conditions are where a driver must reduce speed to maneuver through a warned condition such as Turn, Curve, Reverse Turn, or Reverse Curve signs. Typical perception-reaction time in this condition is 2.5 seconds.

9. Category A Warning Signs
Speed reduction and lane changing
Table 2C-4 in MUTCD
Common examples of Category A signs are Merge or Right Lane Ends

10. Advance Placement of Category A Signs
Posted or 85th Percentile Speed (mph) 20 25 30 35 40 45
Advance Placement Distance (ft)
225
325
450
550
650
750 50 55 60 65 70 75
850
950
1100
1200
1250
1350
Consider the following example:
A driver traveling in the rightmost lane of a freeway with heavy traffic volumes needs to merge left because the rightmost freeway lane ends. The posted or 85th-percentile speed on the freeway is 60 miles per hour. In order to accomplish the merge maneuver, a sign must be located at least 1,100 feet prior to the lane merge location for the driver to have enough perception-reaction time to safety complete the task.

11. Condition B Warning Signs
Deceleration to listed advisory speed
Table 2C-4 in MUTCD
Common examples of Condition B signs are Turn, Curve, Reverse Turn, Reverse Curve, Winding Road (see example)

12. Advance Placement of Category B Signs
Posted or 85 th
percentile speed
Deceleration to listed advisory speed (mph)
for the condition a
(mph) b 10 20 30 40 50 60 70
125 45
175
250
200
150
100 50
250
200
150
100 55
325
275
225
175 60
400
350
300 65
475
425 55
325
275
225
175
100 60
400
350
300
250 65
475
425 70
550
525
500
150 75
650
625
600
450
This slide has some animation to illustrate an example. For instance, the posted or 85th-percentile speed on a two-lane rural highway is 55 miles per hour. The roadway alignment has a reverse curve that requires a driver to decrease their speed to 30 miles per hour. The required advance posting distance for the warning sign should be 175-feet. 70
550
525
500
425
350
250
150 75
650
625
600
525
450
350
250
100 a
Typical conditions are when road users must reduce speed to perform a maneuver. b
Typical co
ndition is to warn of a potential stop.

13. Guide signs Guide and inform drivers Minimize confusion
By giving information to drivers when they need it, we can reduce the unpredictable behavior of drivers who suddenly realize they are going the wrong way or just missed a turn.
Columbia County 27 is a route sign.
The green sign is a destination and distance sign.
Other examples include: street name signs, rest area signs, weight station signing, general service signs, and reference location signs.

14. Placement Longitudinal Lateral offset Mounting height
Place each sign for maximum visibility and effectiveness. The sign location must fit in with the layout of the highway. You must justify any variation from MUTCD practices or applications with an engineering study or engineering judgment. If a sign is placed in a location other than that shown in the MUTCD, document and file the reasons for this placement for future reference. The MUTCD describes sign placement information.
Take the time to check all sign locations; make sure that nothing blocks a motorist’s view of the sign and that it is visible at night. Avoid placing signs in dips, beyond hillcrests, or at other places where motorists cannot see them in enough time to react safely. Make sure that a new sign does not block a motorist’s view of an existing sign. Always consider the possibility that a sign could be hidden by parked trucks or summer foliage or be a hazard to pedestrians.
Locate ground-mounted signs on the right side of the roadway facing approaching traffic, unless another location is required or permitted. Consider signs in any other position to be less important to those in the usual location.

15. Longitudinal Placement
Distance along road from sign to condition to which it refers
Depends on sign type, nature of message, and prevailing traffic speed
Place sign where it can be seen
Examples of longitudinal placement guidelines:
Speed limit signs must be placed at points where the speed limit changes. They must also be placed be installed beyond major intersections and at other locations where it is necessary to remind users of the applicable speed limit. Lastly, they must be installed at jurisdictional boundaries.
Truck escape ramp signs should be located 1-mile and 0.5 miles in advance of the downgrade, and of the ramp.
Destination guide signs should be located 200-feet or more in advance of an intersection in high-speed areas. Destination signs should follow any Junction or Advance Route Turn assemblies that are required.

16. Longitudinal Placement Example
The School Bus Stop Ahead (warning) sign should be installed in advance of locations where a school bus, when stopped to pick up or discharge passengers, is not visible to road users for a distance of 500-feet in advance and where there is no opportunity to relocate the bus stop to provide 500-feet of visibility. The graphic appears to be a good installation...(see next slide)

17. Longitudinal Placement Example 2
School Bus Stop Ahead sign is blocking a county route marker. The county route marker sign and turn assembly should be located at least 300-feet prior the intersecting roadway.

18. Longitudinal Placement Example 3
Sign is after the point of curvature (PC) or beginning of horizontal curve. The advance warning turn sign should be placed in advance of the horizontal alignment change.

19. Lateral Placement Overhead sign supports Ground-mounted signs
6 ft from edge of pavement
Barrier or crash cushion
Ground-mounted signs
12 ft from edge of traveled way
6 ft from edge of shoulder if shoulder > 6 ft wide
Minimum 1 ft from face of curb
Where conditions permit, place signs on roads without curbs so that there is a lateral or side clearance of at least 12 ft (3.6 m) from the edge of the travel lane to the near edge of the sign, or 6 ft (1.8 m) from the edge of the shoulder, where the shoulder is more than 6 ft (1.8 m) wide. When there is something in the way, or the sign will not be visible, the best course is to locate the sign as far from the edge of shoulder as possible.
In areas where space is limited, use a minimum lateral offset of 2 ft (0.6 m). On curbed roads where sidewalk width is limited or where poles are close to the curb, locate the edge of the sign 1 ft (0.3 m) or more from the face of the curb. Place the sign farther from the curb, if possible, to reduce the chance of a vehicle hitting it. This is especially true on corners where trucks turn frequently. Always ensure that the sign and signpost will not block the sidewalk.

20. Lateral Placement Example
New (1 month old) sign that has been clipped by a truck (look at left edge of sign). The sign is too close to the travel lane.

21. Mounting Height
The MUTCD specifies the minimum height of signs so that road users can see them. In urban areas or other locations where other vehicles may block a driver’s view, install signs 7 ft (2.1 m) above the edge of the roadway. In rural areas, 5 ft (1.5 m) is the minimum. Install directional, regulatory, and warning signs on freeways and expressways at least 7 ft (2.1 m) above the pavement edge. If a secondary sign is mounted below a major sign, install the major sign at least 8 ft (2.4 m) and the secondary sign at least 5 ft (1.5 m) above the pavement edge.
The MUTCD does not specify the maximum height of signs, but sometimes it is useful to place the sign higher than normal, for example, so it can be seen over a crest in the road.

22. Mounting Height
On sidewalks or other pedestrian areas, position the sign high enough so pedestrians are not likely to hit their heads on the bottom of the sign panel. At such locations, the clearance to the bottom of the sign must be at least 7 ft (2.1 m).
Overhead mounted signs shall provide a vertical clearance of 17-feet to the sign, light fixture, or sign bridge, over the entire width of the pavement and shoulders. If the vertical clearance of other structures is less than 16-feet, the vertical clearance to the overhead sign should be 1-foot higher than the vertical clearance of the other structures.

23. Retroreflectivity
Regulatory, warning, and guide signs are important and drivers need to see them. That is why the MUTCD mandates these signs shall be retroreflective or lighted so they have essentially the same appearance day and night. Materials used for signs should provide nighttime visibility equal to daytime visibility. Black portions of a sign face need not be reflectorized.

24. Video
Night Lights

25. Retroreflectivity Example
The graphic shows a route sign with turning panel. The figure demonstrates how sign retroreflectivity levels can fade over time. It can be difficult to notice this degradation during the daytime, so plan periodic nighttime inspections. Portable retroreflectometers are a good way to measure retroreflectivity levels of traffic signs. Brightness can also be reduced because of mud or debris splatter. In this case, washing a sign with a soft sponge and mild soap will remove dirt and restore retroreflectivity.

26. Retroreflectivity Example 2
The graphic shows a set of route guide signs. Two signs are clearly visible at night while one is not. The figure demonstrates how sign retroreflectivity levels can fade over time.

27. Sign Tips Use correct sign for situation
Make sure sign is installed correctly
Look at sign and its surroundings
Signs must meet the principles of a traffic control device outlined earlier in this section.
Be sure that the sign is installed correctly, including longitudinal placement, lateral offset, and mounting height.
Be sure that the sign is visible to road users!

28. Sign Installation Example
The Keep Right regulatory sign is used to inform travelers that it is necessary to pass only on the right side of a roadway feature or obstruction. Warning sign on other side is an "end median" sign. Signs are reversed on post!

29. Sign Installation Example 2
Wasn't there something about "clear, simple meaning?” The sign in the graphic indicates that no motor vehicles are permitted to use the road. The No Motor Vehicles sign should be removed or relocated to the position where it is intended.

30. Sign Installation Example 3
Wrong curve sign (Winding Road warning sign with speed advisory is shown in graphic). Should consider a Turn or Curve warning sign. The sign should also be located farther in advance of the curve. Proper posting distance would place it before the previous curve. This is in a series of curves, so this isn't the first sign.

31. Pavement Markings Can be very cost-effective
Hard to see on wet nights or in snow
Must be reapplied regularly
Pavement markings guide and regulate traffic. They improve the safety of a roadway by informing the driver without taking attention from the roadway. We use pavement markings to guide traffic through sharp or multiple curves, delineate road width reductions, and mark no-passing zones. They are especially useful in reducing run-off-road and crossover crash problems.

32. Pavement Markings 2 Centerline markings on two-lane roads:
Required on urban roads that are > 20 ft wide with 6,000 veh/day.
Edgeline markings:
Required on freeways, expressways, and rural arterials > 20 ft wide with 6,000 veh/day
Required on roads with ³ 3 lanes
Centerline markings are recommended on: Two-way paved urban arterials and collectors 20 ft (6.1 m) wide or more with an ADT of 4,000 vehicles per day or greater.
-- Two-way paved rural arterials and collectors 18 ft (5.5 m) wide or more with an ADT of 3,000 vehicles per day or greater.
Centerline pavement markings are required on urban roads that carry more than 6,000 vehicles per day with traveled ways 20 ft (6.1 m) or wider. Edgelines are required on freeways, expressways, and rural arterials with a traveled way width of 20 ft (6.1 m) or more and an ADT of 6,000 vehicles per day or greater. Edgelines are recommended on rural arterials with a 20 ft (6.1 m) or wider traveled way and an ADT of 3,000 vehicles per day or greater.
The three categories of pavement markings are long lines (center and edge lines), transverse lines (stop lines and crosswalks), and special markings (words and symbols).

33. Center Lines Required for: No passing zones Multilane highways
Also used to:
Reduce head-on collisions
Guide traffic through curves
Other centerline applications include: (1) no passing zones on two-way roadways at lane reduction transitions, (2) approaches to highway rail-grade crossings, (3) horizontal and vertical curves where passing is prohibited, (4) reversible lanes and (5) delineation of median island formed by pavement markings.
Use of centerlines in no passing zones can reduce all crashes by 36 percent.

34. Edge Lines Used with center lines Road shifts or narrows
Guide past obstacles
Mark paved shoulders
Used to separate traffic that have the same direction of travel. For instance, solid white edgelines may be used to separate through traffic lanes from auxiliary lanes, such as truck climbing lanes, left- or right-turn lanes, and other special use lanes. Lane lines are required on all freeways and Interstate highways.

35. Transverse Lines Stop lines Railroad clearance lines Crosswalks
Stop lines indicate the point on an approach at which vehicle are intended to or required to stop. They must be 12- to 24-inches wide.
Crosswalk markings provide guidance for pedestrians who are crossing roadways by delineating the intended path. They should be between 6- and 24-inches wide and be separate by at least 6-feet.
Railroad clearance lines should be 8-ft from the gate, but no closer than 15-ft to the nearest rail.

36. Traffic Control Device Maintenance
Use inventory to plan maintenance
Inspect at least yearly
Conduct study before removal
Best safety device in the world is no good if you can't maintain it
Inventory can help track, plan and prioritize maintenance
Problem is: is the device unneeded because there is no safety problem, or is the device you want to remove preventing a safety problem?
Pavement markings become less effective as the markings wear. New markings provide much better guidance than worn ones, especially at night. Much the same way that reduced retroreflectivity makes signs difficult to see at night, pavement marking reflectivity is often lost before wear is apparent during daylight.
Several States supplement pavement markings with milled or other types of rumble strips. The case for using rumble strips is that the abrupt change in sound and pavement texture alerts drivers that they are leaving the roadway, crossing the centerline, or approaching a STOP sign. Rumble strips are commonly used on Interstates, and are increasingly being used on two-lane rural roads.

37. Inspection Items Bad retroreflectivity Bent signs or posts
Proper placement
Fading, weathering
Vegetation
A complete inventory is one of the most useful tools for effectively maintaining your traffic control devices. An inventory helps you plan and budget your maintenance efforts and it makes replacing missing signs easier. The initial inventory can be labor-intensive, but once completed, it is easy to maintain and well worth the effort.
There are several ways to keep your inventory. It can be as basic as a paper system such as index cards or in a binder. It can be more high-tech and take advantage of computer software. Regardless of the method you use, it should be flexible enough so that you can add new signs and delete removed signs. It is also a good place to document repairs. Computer inventory systems also allow you to add information on sign condition, and based on the condition and the primacy of the sign, prioritize repairs. Figure 13 is an example of a sign in poor condition. Be sure to include the sign location in an inventory of signs requiring replacement.

38. Inspection Example
Example of night-time reflectivity loss well before wear is visible in daylight.

39. Exercise: Sign layout

40. Sign Problem 1 Each tick mark in the example is 100-feet.
The posted speed on both roads is 55 miles per hour.
Where should the Stop Ahead sign be placed?
Answer: Based on Table 2C-4, the Stop Ahead sign should be placed 325-feet in advance of the stop sign.
Note that the Stop Ahead sign is animated.

41. Sign Problem 2 Point of curvature SL = 55 mph Curve speed = 45 mph
Sign exercise 2
Determine posting distance for Stop Ahead sign – the posted speed limit is 55 miles per hour. Per the last example, the sign should be located 325-ft prior to intersection. What about the Curve warning sign? It may be used in advance of alignment changes.
What problem does this pose? The Stop Ahead sign may block a driver’s view of the Curve warning sign. The Stop Ahead sign should be relocated to a position near the end of the curve (closer to stop sign that is easily viewed by a motorist). Also, the Curve sign does not have a speed advisory plaque because the reduction is less than 15 miles per hour. As such, the Curve sign is properly placed at the point of horizontal curvature.

42. Traffic Control Devices Summary
MUTCD
Principles
Signs
Pavement Markings
The MUTCD provides standards and other guidelines for using traffic control devices, which are the way highway departments communicate with drivers. They should fulfill a need, command attention, convey a clear meaning, command respect, and give adequate time for drivers to respond. Regulatory, warning, and guide signs have standard colors, size, and placement guidelines―all are outlined in the MUTCD. Agencies should routinely check signs to monitor their retroreflective properties, especially at night. Pavement markings and delineators guide drivers by highlighting edgelines and lane lines, especially at night and in poor weather. Agencies should routinely monitor and evaluate their effectiveness. Developing an inventory of signs, pavement markings, and delineators is a useful way for agencies to effectively manage traffic control devices. Although labor intensive at first, an inventory can help improve traffic control device maintenance.