MOT Lane Closure & Detour Planning 5 — Questions and Answers
Question 1: What is the primary function of a buffer space (longitudinal buffer) within a temporary traffic control zone?
- To store construction materials and equipment
- To provide a safety margin between the taper and the active work space (Correct answer)
- To allow workers to park their personal vehicles
- To separate opposing traffic streams
Correct answer: To provide a safety margin between the taper and the active work space
The longitudinal buffer space is an unoccupied area between the end of the taper and the start of the activity area, providing a safety margin if a vehicle fails to merge in time.
Question 2: When closing a lane on a curve, where should the first channelizing device in the taper be placed relative to the curve?
- At the sharpest point of the curve for maximum visibility
- Upstream (in advance) of the curve so drivers can see the lane closure before entering the curve (Correct answer)
- At the midpoint of the curve
- Downstream of the curve where sight lines improve
Correct answer: Upstream (in advance) of the curve so drivers can see the lane closure before entering the curve
Placing the taper start before the curve gives drivers visibility of the closure while they still have a straight sight line, preventing surprise lane changes on the curve itself.
Question 3: What type of device is used at the upstream end of a lane closure to 'shadow' the work zone and absorb the energy of an errant vehicle?
- Arrow board
- Truck-mounted attenuator (TMA) (Correct answer)
- Portable changeable message sign
- Type III barricade
Correct answer: Truck-mounted attenuator (TMA)
A truck-mounted attenuator is a crash cushion mounted on the back of a shadow vehicle positioned upstream of the work space to protect workers from vehicle intrusion.
Question 4: Under MUTCD guidelines, which type of arrow board display mode is PROHIBITED during moving operations (e.g., a slow-moving lane closure)?
- Flashing arrow pointing in the closure direction (Correct answer)
- Caution (diamond or chevron) mode
- Sequential flashing mode across the full board
- Single blinking light mode
Correct answer: Flashing arrow pointing in the closure direction
A flashing arrow mode is inappropriate for moving operations because it implies a stationary diversion; caution/diamond mode is recommended for moving work zones.
Question 5: A lane closure TTC plan requires a tangent (straight-line) taper. The road is 55 mph, lane width is 12 feet, and the formula is L = WS for speeds ≤45 mph or L = WS²/60 for speeds >45 mph. What minimum taper length applies?
- 495 feet
- 550 feet
- 605 feet (Correct answer)
- 660 feet
Correct answer: 605 feet
For speeds above 45 mph, L = WS²/60 = 12 × (55²) / 60 = 12 × 3025 / 60 ≈ 605 feet.
Question 6: When a detour adds significant travel distance and time, which community stakeholder group should be notified FIRST to coordinate emergency response during the closure?
- Local school districts
- Fire, police, and EMS agencies (Correct answer)
- Chamber of commerce
- Transit authorities
Correct answer: Fire, police, and EMS agencies
Emergency services must know about detours to update response routes and ensure they can reach any location within their jurisdiction without delay.
Question 7: At the end of a lane closure operation, in what order should temporary traffic control devices be removed?
- Downstream to upstream (starting at the far end from approaching traffic) (Correct answer)
- Upstream to downstream (starting closest to approaching traffic first)
- All devices simultaneously by multiple crew members
- Randomly, based on worker location
Correct answer: Downstream to upstream (starting at the far end from approaching traffic)
Devices are removed from the downstream (termination) end first and progressed upstream, so workers removing devices are always protected by the remaining upstream setup.
MOT Lane Closure & Detour Planning 5
What is the primary function of a buffer space (longitudinal buffer) within a temporary traffic control zone?