MOT Traffic Control Devices & Placement Standards 4 — Questions and Answers
Question 1: According to MUTCD, what is the correct action when a flagger cannot be seen by an approaching driver due to a curve or hill?
- Post an additional flagger or a high-intensity warning light at the hidden location (Correct answer)
- Increase the flagger's visibility vest brightness
- Place a stop sign at the curve
- Use a pilot car instead
Correct answer: Post an additional flagger or a high-intensity warning light at the hidden location
When sight distance is limited, an additional flagger or automated flagger assistance device must be placed in advance to warn approaching traffic.
Question 2: In a temporary traffic control zone, vertical panels are typically used to:
- Provide overhead height warnings
- Delineate the edge of a travelled way at night or in low-visibility conditions (Correct answer)
- Support portable signs on highways
- Replace Type III barricades on low-speed roads
Correct answer: Delineate the edge of a travelled way at night or in low-visibility conditions
Vertical panels are primarily used to delineate the edge of the travelled way, especially at night or in low visibility, due to their retroreflective strips.
Question 3: What does the 'W' designation in a sign code such as W20-1 indicate?
- Work zone
- Warning (Correct answer)
- Width restriction
- Westbound
Correct answer: Warning
In MUTCD sign codes, 'W' stands for Warning, and W20 series signs are specifically warning signs related to highway work zones.
Question 4: Under what condition is it acceptable to use painted edge lines alone as the only TTC measure in a short-duration work zone?
- Never — at least cones are always required
- When the work activity is fully within the shoulder and no workers are in the roadway (Correct answer)
- When speed limits are under 25 mph
- Only during daylight hours on local roads
Correct answer: When the work activity is fully within the shoulder and no workers are in the roadway
If work is confined entirely within the shoulder with no workers in the travel lane, edge lines alone may be sufficient for very short-duration operations.
Question 5: Which factor most directly determines the required taper length (L) for a merging taper?
- Number of cones available on-site
- Speed limit and the width of the lane being closed (Correct answer)
- Time of day and visibility conditions
- Contractor's schedule and budget
Correct answer: Speed limit and the width of the lane being closed
Taper length L is calculated using the formula L = WS (width × speed) or L = WS²/60 depending on speed, so speed limit and lane width are the primary factors.
Question 6: A truck-mounted attenuator (TMA) is best described as a:
- Sign support system mounted on heavy trucks
- Impact-absorbing device attached to the rear of a shadow vehicle (Correct answer)
- Portable rumble strip system for speed reduction
- Overhead gantry sign structure on interstate highways
Correct answer: Impact-absorbing device attached to the rear of a shadow vehicle
A TMA is an impact-absorbing device mounted on the rear of a shadow vehicle to protect workers by cushioning errant vehicle impacts.
Question 7: When closing a lane on a divided highway, the recommended sequence for placing cones to form a taper is:
- Start from the downstream end and work back toward approaching traffic (Correct answer)
- Start from the upstream end and work toward the downstream end
- Place cones simultaneously from both ends toward the middle
- Place cones in the opposite direction of traffic flow
Correct answer: Start from the downstream end and work back toward approaching traffic
Cones should be placed starting from the downstream (far) end working back toward approaching traffic so workers are always protected by already-placed devices.
MOT Traffic Control Devices & Placement Standards 4
According to MUTCD, what is the correct action when a flagger cannot be seen by an approaching driver due to a curve or hill?