Question 1

Cone color, material, and minimum height

Accepted Answer

Cones shall be predominantly orange and made of a material that can be struck without causing damage to the impacting vehicle. For daytime and low-speed roadways, cones shall be not less than 18 inches in height. On freeways and other high-speed highways, at night on all highways, or when more conspicuous guidance is needed, cones shall be a minimum of 28 inches in height.

Question 2

Nighttime retroreflectorization of 28- to 36-inch cones

Accepted Answer

For nighttime use cones shall be retroreflectorized or equipped with lighting devices. For cones 28 to 36 inches in height, retroreflectorization shall be a 6-inch wide white band located 3 to 4 inches from the top of the cone plus an additional 4-inch wide white band located approximately 2 inches below the 6-inch band.

Question 3

Retroreflectorization of cones taller than 36 inches

Accepted Answer

Cones more than 36 inches in height shall have horizontal, circumferential, alternating orange and white retroreflective stripes 4 to 6 inches wide, with a minimum of two orange and two white stripes, the top stripe being orange, and any non-retroreflective spaces between stripes not exceeding 3 inches in width.

Question 4

Permitted uses of traffic cones

Accepted Answer

Traffic cones may be used to channelize road users, divide opposing vehicular traffic lanes, divide lanes when two or more lanes are kept open in the same direction, and delineate short-duration maintenance and utility work.

Question 5

Preventing cone displacement by wind or traffic

Accepted Answer

Steps should be taken to minimize the possibility of cones being blown over or displaced by wind or moving vehicular traffic. Cones may be doubled up to increase their weight, and ballast should be kept to the minimum amount needed.

Question 6

Channelizing devices must be crashworthy

Accepted Answer

Designs of various channelizing devices shall be as shown in Figure 6K-1. All channelizing devices shall be crashworthy.

Question 7

Channelizing device spacing for tapers and tangents

Accepted Answer

The spacing between cones, tubular markers, vertical panels, drums, and barricades should not exceed a distance in feet equal to 1 times the speed limit in mph when used for taper channelization, and should not exceed a distance in feet equal to 2 times the speed limit in mph when used for tangent channelization.

Question 8

Extending channelizing devices beyond transition area

Accepted Answer

When channelizing devices have the potential of leading vehicular traffic out of the intended vehicular traffic space, the channelizing devices should be extended a distance in feet of 2 times the speed limit in mph beyond the downstream end of the transition area.

Question 9

Channelizing device retroreflective color day and night

Accepted Answer

The retroreflective material used on channelizing devices shall display a similar color day or night.

Question 10

Restriction on owner/manufacturer identification on channelizing devices

Accepted Answer

Information identifying the owner or manufacturer shall not be displayed on any portion of the device visible to approaching road users; where the highway agency, contractor, or supplier name and telephone number are displayed on the non-retroreflective surface, that area shall be non-retroreflective and not over 2 inches in height.

Question 11

Replacement of non-serviceable channelizing devices

Accepted Answer

Channelizing devices that are no longer serviceable shall be replaced.

Question 12

Redirection of road users in transition area

Accepted Answer

Except for mobile operations, when redirection of the road users' normal path is required, road users shall be directed from the normal path to a new path with appropriate channelizing devices, traffic control devices, and/or TTC methods.

Question 13

Taper length criteria by taper type

Accepted Answer

Merging taper: at least L; Shifting taper: at least 0.5 L; Shoulder taper: at least 0.33 L; One-Lane, Two-Way Traffic taper: 50 feet minimum, 100 feet maximum; Downstream taper: 50 feet minimum, 100 feet maximum.

Question 14

Taper length calculation formulas

Accepted Answer

For speeds 40 mph or less: L = (W x S^2) / 60. For speeds 45 mph or more: L = W x S. Where L = taper length in feet, W = width of offset in feet, and S = posted speed limit, off-peak 85th-percentile speed prior to work starting, or the anticipated operating speed in mph.

Question 15

Downstream taper length and device spacing

Accepted Answer

If used, a downstream taper should have a minimum length of 50 feet and a maximum length of 100 feet with devices placed at a spacing of approximately 20 feet.

Question 16

One-lane, two-way traffic taper length and spacing

Accepted Answer

A taper having a minimum length of 50 feet and a maximum length of 100 feet with channelizing devices at approximately 20-foot spacing should be used to guide traffic into the one-lane section, and a downstream taper should be used to guide traffic back into their original lane.

Question 17

Shifting taper length

Accepted Answer

A shifting taper should have a length of approximately ½ L.

Question 18

Shoulder taper length

Accepted Answer

If used, shoulder tapers should have a length of approximately 1/3 L. If a shoulder is used as a travel lane, a normal merging or shifting taper should be used.

Question 19

Recommended advance warning sign minimum spacing

Accepted Answer

Recommended minimum spacing between advance warning signs (dimensions A/B/C): Urban low speed 100/100/100 feet; Urban high speed 350/350/350 feet; Rural 500/500/500 feet; Expressway/Freeway 1,000/1,500/2,640 feet.

Question 20

Advance warning sign placement on urban streets

Accepted Answer

On urban streets, the effective placement of the nearest warning sign to the TTC zone, in feet, should range from 4 to 8 times the speed limit in mph, with the high end used when speeds are relatively high.

Question 21

Advance warning sign placement on rural highways

Accepted Answer

On rural highways the effective placement of the first warning sign in feet should be from 8 to 12 times the speed limit in mph, and the advance warning area should extend 1,500 feet or more for open highway conditions.

Question 22

Advance warning sign placement on freeways and expressways

Accepted Answer

On freeways and expressways, advance warning sign placement should extend as far as ½ mile or more.

Question 23

Stopping sight distance as a function of speed

Accepted Answer

Stopping sight distance values (posted/off-peak 85th-percentile/anticipated operating speed): 20 mph=115 ft; 25 mph=155 ft; 30 mph=200 ft; 35 mph=250 ft; 40 mph=305 ft; 45 mph=360 ft; 50 mph=425 ft; 55 mph=495 ft; 60 mph=570 ft; 65 mph=645 ft; 70 mph=730 ft; 75 mph=820 ft.

Question 24

No work or storage within buffer space

Accepted Answer

Neither work activity nor storage of equipment, vehicles, or material should occur within a buffer space.

Question 25

High-visibility safety apparel for workers in TTC zone

Accepted Answer

For daytime and nighttime activity, all workers, including emergency responders, within the right-of-way who are within the TTC zone shall wear high-visibility safety apparel that meets the Performance Class 2 or 3 requirements of ANSI/ISEA 107-2015, or equivalent revisions.

Question 26

High-visibility apparel color requirements

Accepted Answer

The apparel background (outer) material color shall be fluorescent orange-red, fluorescent yellow-green, or a combination of the two as defined in the ANSI standard. The retroreflective material shall be orange, yellow, white, silver, yellow-green, or a fluorescent version of these colors.

Question 27

High-visibility apparel for law enforcement handling lane closures

Accepted Answer

When uniformed law enforcement personnel are used to direct traffic, investigate crashes, or handle lane closures, obstructed roadways, and disasters, high-visibility safety apparel as described in Section 6C.05 shall be worn by the law enforcement personnel.

Question 28

Flagger high-visibility apparel for nighttime activity

Accepted Answer

For flagger wear during nighttime activity, high-visibility safety apparel that meets the Performance Class 3 requirements of ANSI/ISEA 107-2015, labeled as meeting the ANSI 107-2015 standard performance for Class 3 risk exposure, should be worn.

Question 29

Speed limit reduction limited to 10 mph

Accepted Answer

A TTC plan should be designed so that vehicles can travel through the TTC zone with a speed limit reduction of no more than 10 mph; a reduction of more than 10 mph should be used only when required by restrictive features.

Question 30

MUTCD is the national standard for traffic control devices

Accepted Answer

The MUTCD approved by the Federal Highway Administrator is the national standard for all traffic control devices installed on any street, highway, or bicycle trail open to public travel.

Question 31

State MUTCD substantial conformance requirement

Accepted Answer

Where State MUTCDs or Supplements are required, they shall be in substantial conformance with the national MUTCD, conforming as a minimum to the Standard statements in the national MUTCD, and shall not contain statements that contravene or negate Standard or Guidance statements in the national MUTCD.

Question 32

Two-year adoption of MUTCD changes by States

Accepted Answer

States and other Federal agencies shall adopt changes issued by the FHWA to the National MUTCD within two years from the effective date of the final rule.

Question 33

Traffic control devices in construction areas must conform to MUTCD

Accepted Answer

All traffic control devices installed in construction areas using Federal-aid funds shall conform to the MUTCD, and traffic control plans for handling traffic and pedestrians and protecting workers shall conform to 23 CFR part 630, subpart J.

Close a lane (work zone) in Federal baseline