IMSA Signs & Markings I flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

MUTCD Standard statement

A mandatory requirement in the MUTCD, identified by the word "shall." Compliance is required, and a deviation needs an approved exception or a formal experiment.

MUTCD Part 6

The part of the MUTCD covering temporary traffic control: work zones, incident management, and the device requirements for construction and maintenance operations on all public roads.

Standard Highway Signs book

FHWA publication containing the official designs, dimensions, and layouts for MUTCD sign and pavement marking designs; sign shops fabricate compliant signs from these drawings rather than from the MUTCD text.

23 CFR 655

Federal regulation adopting the MUTCD; it requires compliance on all highways open to public travel, including private roads open to public travel, not only federally funded routes.

AASHTO Green Book

A Policy on Geometric Design of Highways and Streets; the source of stopping sight distance, lane width, and clear zone values used to justify sign placement and marking decisions.

Engineering study

A documented analysis of traffic, field conditions, and crash data performed by a qualified professional. Many MUTCD option-level decisions, such as speed limits and no-passing zones, require one.

Octagon sign shape

Reserved exclusively for STOP signs. The shape alone identifies the requirement, so drivers can recognize it even when the legend is obscured or the face has faded.

Fluorescent yellow-green signs

Sheeting color reserved for school, pedestrian, and bicycle warning signs; its higher chromaticity improves detection in peripheral vision and in low-light conditions compared with standard yellow.

Sign mounting height

Measured from the bottom of the sign to the top of the curb or edge of traveled way: 5 ft minimum in rural areas, 7 ft in business or residential areas with pedestrians.

ASTM D4956

Standard specification classifying retroreflective sheeting into Types I through XI. Agencies specify a type to control brightness, durability, and cost rather than naming a manufacturer's product.

Breakaway sign supports

Supports designed to yield or separate on impact and crash-tested to NCHRP 350 or MASH; required on high-speed roads and placed outside the clear zone where practical.

Minimum sign lateral offset

The clear distance from the edge of the traveled way to the nearest edge of the sign: 6 ft in rural areas and 2 ft from the curb face in urban areas.

Blue guide signs

Color used for motorist services signs such as gas, food, lodging, and hospitals, and for evacuation routes; never used for regulatory or warning messages.

Broken lane line pattern

A 10-ft stripe with a 30-ft gap, the standard pattern that separates traffic lanes moving in the same direction on a normal tangent section.

Six-inch edge lines

Required on freeways, expressways, and interstates and commonly used where speeds are 45 mph or higher, compared with the standard 4-in longitudinal line width.

Thermoplastic pavement marking

Hot-applied material heated to roughly 400 to 425 degrees F and applied 60 to 120 mils thick; durable, with glass beads dropped on while molten to provide retroreflectivity.

Raised pavement markers

Reflectorized devices that supplement or temporarily replace pavement markings; snowplowable types are required where plows operate, and they must be maintained as part of the marking system.

Double solid yellow line

Marks a no-passing zone in both directions; passing is prohibited for traffic on either side, and the zone limits are set from stopping sight distance analysis.

Dotted lane line pattern

A 3-ft stripe with a 9-ft gap, used to extend lane lines through interchanges, at lane drops, and across exit gore areas where a broken line would mislead drivers.

Yellow pavement markings

Delineate opposing traffic movements and mark the left edge of divided highways, ramps, and one-way roadways; white markings separate same-direction traffic and mark the right edge.

Three sign retro assessment methods

Nighttime visual inspection, retroreflectometer measurement, and expected service life; the MUTCD also accepts blanket replacement and control-sign comparison as management methods.

Thirty-meter geometry

Standard pavement marking retroreflectivity measurement geometry of 88.76 degree entrance angle and 1.05 degree observation angle, required by ASTM E1710 and used by handheld reflectometers.

Sign inventory requirements

A database recording location, MUTCD code, size, sheeting type, installation date, expected service life, and inspection results, used to schedule replacement before retroreflectivity falls below minimums.

MUTCD Table 2A-3

Table of minimum maintained retroreflectivity levels for signs, listed by sign color and sheeting type; agencies must keep in-service signs at or above these values.

Nighttime sign inspection

A trained observer drives the route at night at normal speed and judges each sign as passing or failing against a comparison sign or panel of known retroreflectivity.

Pavement marking retro thresholds

Commonly used agency maintenance levels are 150 mcd per square meter per lux for white and 100 for yellow longitudinal markings; thresholds vary by state and roadway class.

Five parts of a TTC zone

Advance warning area, transition area, activity area containing buffer space, work space and traffic space, and termination area; each is sized from speed and work duration.

Merging taper formula

Taper length L equals W times S where speed is 40 mph or less, and W times S-squared divided by 60 at 45 mph and above, with W in feet and S in mph.

Buffer space

The unused longitudinal area between the end of the transition taper and the work space; it must equal stopping sight distance and contain no workers, equipment, or materials.

Cone height requirements

Minimum 18-in cones where speeds are 40 mph or less and 28-in cones where speeds are 45 mph or higher; larger devices suit freeway and high-speed nighttime use.

ANSI/ISEA 107 Class 3 apparel

High-visibility clothing required for nighttime work zones and where sight distance or site complexity is limited; Class 2 is the minimum for typical daytime operations.

Truck-mounted attenuator

A crash cushion mounted on a shadow vehicle positioned behind mobile or short-duration work to protect workers from errant vehicles approaching from upstream.