LARE Section 3 flashcards

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

Design-bid-build delivery

Owner contracts separately with a designer and a contractor. Design is complete before bidding. Lowest responsive bidder builds. Longest schedule, but clear division of design and construction responsibility.

Design-build delivery

One entity holds both design and construction contracts. Owner states performance criteria. Faster delivery and fewer owner change orders, but the owner has less control over design detail.

CM at risk

Construction manager holds a guaranteed maximum price and subcontracts the trade work. Owner gains early cost and schedule input, and the CM carries risk above the GMP.

Agency CM

Construction manager acts only as the owner's adviser, for a fee, with no construction risk and no GMP. The owner retains all cost-overrun risk.

Retainage

A percentage, commonly 5 to 10 percent, withheld from each progress payment until substantial completion or as the contract states. It reduces contractor cash flow and tends to raise bid prices.

Critical path

The longest continuous path through the schedule network. It has zero total float, so any delay on it delays project completion unless the schedule is compressed.

Total float formula

Total float equals late start minus early start, which also equals late finish minus early finish. Total float is shared along a path; free float is specific to one activity.

Construction change directive

A written order directing the contractor to proceed with work before price and time are agreed. It differs from a change order, which is a signed agreement on scope, price, and time.

Slope percent formula

Slope percent equals rise divided by run, times 100. A 2 percent slope drops 2 feet per 100 feet. A 4:1 ratio equals 25 percent; 3:1 equals 33 percent.

Accessible route running slope

Maximum running slope for an accessible route is 1:20, or 5 percent. Anything steeper is a ramp and must meet ramp requirements, including landings and handrails.

Ramp slope and rise limits

Accessible ramps have a maximum running slope of 1:12, or 8.33 percent, and a maximum rise of 30 inches per run. Landings at top and bottom are at least 60 inches long.

Accessible route cross slope

Maximum cross slope on an accessible route is 1:48, about 2 percent. Steeper cross slopes cause wheelchair drift and are a common compliance failure on site plans.

Accessible passing space

Where a route is narrower than 60 inches, provide a 60 by 60 inch passing space at intervals. Continuous clear width minimum is 36 inches.

Minimum drainage slopes

Paved surfaces drain at a minimum of 1 to 2 percent; turf at about 2 percent. Level spreaders convert concentrated flow into sheet flow to prevent erosion.

Cut and fill balance

Sum cut and fill volumes separately. Apply a shrinkage or swell factor, then the net difference gives haul-off or borrow volume needed to balance the site.

Contour reading rule

Contours run perpendicular to the fall line. Closely spaced contours mean steep grade; widely spaced mean gentle grade. Touching or crossing contours indicate an overhang or drawing error.

Concrete water-cement ratio

The water-cement ratio governs concrete strength and durability. Lower water-cement ratio gives higher strength. A common site mix is 1:2:3 cement to sand to aggregate by volume.

Concrete curing requirements

Keep concrete moist and above about 50 degrees Fahrenheit. Cure 7 days for normal cement, 3 days for high-early-strength. Cold weather slows strength gain.

Asphalt pavement layers

Place base course, then binder course, then surface course. Compact each lift. Apply a prime coat between the base and the asphalt layers.

Segmental retaining wall geogrid

Geogrid reinforcement length is typically 60 to 70 percent of wall height. Use granular drainage fill and a perforated drain at the base of the wall.

Pressure-treated lumber fasteners

Use stainless steel or hot-dip galvanized fasteners with pressure-treated lumber. Preservative salts corrode standard fasteners. Specify ground-contact rated lumber where it touches soil.

MasterFormat divisions

Division 01 general requirements, 02 existing conditions, 03 concrete, 31 earthwork, 32 exterior improvements, 33 utilities. Specifications are organized by these divisions.

Shop drawings vs. submittals

Shop drawings are contractor-prepared fabrication and installation details. Submittals is the broader category and also includes product data, samples, and mockups.

Punch list

A list of incomplete or defective work identified at substantial completion. The contractor corrects these items before final completion and final payment.

Rational method formula

Q equals C times i times A. Q is peak flow in cubic feet per second, C is the runoff coefficient, i is rainfall intensity in inches per hour, A is area in acres.

Runoff coefficients

Lawn 0.15 to 0.35, gravel about 0.35, asphalt 0.90 to 0.95, roofs 0.90 to 0.95. For mixed areas, compute a composite C weighted by area.

Time of concentration

The time for runoff from the most hydraulically remote point to reach the design point. It sets the rainfall intensity used in the rational method.

Detention vs. retention

Detention holds stormwater temporarily and releases it slowly. Retention holds it permanently through infiltration or a permanent pool. Detention is sized to limit peak discharge.

Pre- and post-development flows

Detention must be sized so post-development peak discharge does not exceed pre-development peak discharge for the design storm.

Bioretention components

Engineered soil media, surface ponding depth, an underdrain, and an overflow. Treat the water-quality volume first, then attenuate larger storms.

Grass swale design

Side slopes 3:1 or flatter, longitudinal slope of 1 to 4 percent, and check dams to slow flow and promote infiltration.

Manning's equation

V equals 1.486 over n, times R to the two-thirds power, times S to the one-half power. n is about 0.013 for concrete pipe and 0.03 to 0.04 for grass channels.