Free PE Transportation Exam Flashcards

Scheduling technique that identifies the longest sequence of dependent activities (the critical path) determining minimum project duration. Activities on the critical path have zero total float, so any delay on them delays the whole project.

The amount of time an activity can be delayed without delaying the project's overall completion date. Critical-path activities have zero total float.

Break-even months = (Purchase price minus Salvage value) divided by Monthly rental rate. Below the break-even period, renting is cheaper; beyond it, purchasing is more economical (ignoring time value of money and operating cost).

Estimates cut/fill volume between two cross sections: V = L x (A1 + A2) / 2, where L is the distance between stations and A1, A2 are the end-section areas. The result is commonly divided by 27 to convert cubic feet to cubic yards.

HCM qualitative measure of traffic-flow operating conditions, graded A (best, free flow) through F (worst, breakdown/forced flow), based on measures like density, speed, or delay depending on the facility type.

PHF = V / (4 x V15), where V is the total hourly volume and V15 is the volume during the peak 15-minute period. PHF ranges from 0.25 to 1.0; values closer to 1.0 indicate flatter (less peaked) demand within the hour.

The ratio of actual or projected traffic demand (v) to the roadway's capacity (c) under prevailing conditions. A v/c ratio approaching or exceeding 1.0 indicates the facility is operating at or beyond capacity (LOS F).

Estimates the number of trips produced by and attracted to a land use, typically using rates or equations from the ITE Trip Generation Manual based on land-use type and independent variables such as square footage or dwelling units.

R (crashes/MEV) = (A x 1,000,000) / (ADT x 365 x N), where A is the number of crashes, ADT is average daily entering volume, and N is the number of years of data. Normalizes crash frequency for comparison across sites.

A multiplier from the AASHTO Highway Safety Manual representing the expected change in crash frequency from a specific roadway treatment. CMF less than 1.0 indicates a crash reduction; CMF greater than 1.0 indicates an expected increase.

TRB reference (6th edition, 2016) supplied electronically on the PE Transportation exam. Provides methods for analyzing capacity and LOS for freeways, signalized and unsignalized intersections, roundabouts, and multimodal facilities.

The total roadside border area, starting at the edge of the traveled way, available for safe use by errant vehicles. Width depends on design speed, traffic volume, and roadside slope per AASHTO's Roadside Design Guide.

Recoverable slopes (1V:4H or flatter) let most errant drivers regain control. Non-recoverable slopes (steeper than 1V:4H but 1V:3H or flatter) are traversable but drivers usually can't stop or steer back. Critical slopes (steeper than 1V:3H) risk vehicle rollover.

A traffic barrier is considered when the consequence of leaving the roadway (e.g., steep slope, fixed object, water) is judged more severe than the consequence of impacting the barrier itself. Barriers redirect vehicles rather than eliminate risk.

A roadside device placed in front of a fixed object or gore area that absorbs impact energy through gradual, controlled deceleration, reducing the severity of head-on and side impacts for errant vehicles.

Per ADA/PROWAG accessibility guidance referenced in AASHTO's Guide for the Planning, Design, and Operation of Pedestrian Facilities, sidewalk cross slope is limited to a maximum of 2% (1:48) to keep surfaces usable for wheelchair users.

Defines curve sharpness for highway design: D = 5,729.58 / R, where R is the radius in feet. A smaller radius produces a sharper, higher-degree curve.

The distance from the midpoint of a circular curve's chord to the midpoint of the curve arc: M = R x [1 - cos(Delta/2)], where R is the radius and Delta is the curve's central (deflection) angle.

e + f = V^2 / (15R), U.S. customary units, where e is the superelevation rate (ft/ft), f is the side-friction factor, V is design speed (mph), and R is curve radius (ft). Balances centripetal force on a curve.

R(min) = V^2 / [15 x (e(max) + f(max))]. Derived from the superelevation formula using the maximum allowable superelevation rate and side-friction factor for the design speed.

On a horizontal curve, the middle-ordinate offset (m) between the centerline and a sight obstruction is: m = R x [1 - cos(28.65 x S / R)], where S is the required sight distance and R is the curve radius (ft).

Extra pavement width added on sharp horizontal curves so the design vehicle's swept path (off-tracking) stays within the travel lane. Widening increases as radius decreases and design-vehicle wheelbase increases.

SSD = 1.47Vt + V^2 / [30 x (a/32.2 +/- G)], where V is design speed (mph), t is brake reaction time (AASHTO uses 2.5 s), a is deceleration rate (AASHTO uses 11.2 ft/s^2), and G is grade (+ uphill, - downhill).

L = AS^2 / 2158, where A is the algebraic difference in grades (%), S is stopping sight distance (ft), and L is curve length (ft). The constant 2158 comes from AASHTO's 3.5-ft driver eye height and 2.0-ft object height.

K = L / A, the horizontal distance (ft) needed to achieve a 1% change in grade. Larger K means a flatter, longer curve. Design tables give minimum K by design speed for both crest (SSD) and sag curves.

L = AS^2 / (400 + 3.5S), based on a 2.0-ft headlight height and a 1-degree upward divergence angle. This headlight sight-distance criterion generally governs sag curve length for nighttime driving.

The minimum sight distance on a two-lane road needed for a driver to safely complete a passing maneuver against opposing traffic. PSD values are substantially longer than SSD values at the same design speed.

The sight distance an entering or turning driver at a stop-controlled or uncontrolled intersection needs to see approaching major-road traffic: ISD = 1.47 x V(major) x t(g), where t(g) is the design time gap for the maneuver, which varies by vehicle type and turning movement.

Core geometric elements include the inscribed circle diameter, central island, circulatory roadway width, and entry/exit widths and curvature. Design deflects vehicle paths to slow speeds and requires yield-on-entry to circulating traffic.

The most common freeway-to-arterial interchange type: ramps connect directly to signalized or stop-controlled at-grade intersections on the crossroad, minimizing structure cost but requiring intersection capacity analysis.

Use of pavement markings, islands, or medians to separate and direct conflicting traffic movements into defined paths through an intersection, reducing the number and severity of potential conflict points.

Right- or left-turn lanes are typically warranted when turning volume, through volume, and operating speed combine to create unacceptable delay or crash risk for through traffic. Volume-based warrant charts guide the decision.

Y = t + V / [2(a + 32.2G)], where t is perception-reaction time (about 1.0 s), V is approach speed (ft/s), a is deceleration rate, and G is grade. Gives drivers time to stop or clear the intersection before conflicting movements start.

AR = (w + L) / V, where w is the intersection crossing (curb-to-curb) width, L is vehicle length, and V is approach speed (ft/s). Allows a vehicle that enters on yellow to clear the conflict area before the next phase starts.

The MUTCD lists numbered signal warrants (e.g., eight-hour and four-hour vehicular volume, peak hour, pedestrian volume, school crossing, coordinated signal system, crash experience, roadway network). Meeting at least one warrant justifies, but does not require, signal installation.

The MUTCD uses a default pedestrian walking speed of 3.5 ft/s to calculate the flashing-don't-walk (clearance) interval. A slower speed should be used where pedestrians with mobility limitations routinely cross.

Manual on Uniform Traffic Control Devices (2009 edition with Revisions 1 and 2, the version listed in the current NCEES Transportation standards). The FHWA standard governing the design, application, and placement of signs, markings, and signals on public roads.

Signs fall into three main functional classes: Regulatory (R-series, state laws and rules), Warning (W-series, advance notice of conditions), and Guide (informational/wayfinding, e.g., route markers and destination signs).

MUTCD merging taper: L = WS^2/60 for posted speeds of 40 mph or less; L = WS for posted speeds of 45 mph or greater (L in ft, W = lateral offset width in ft, S = speed in mph).

A TTC zone is divided into four areas in sequence: advance warning area, transition area (tapers), activity area (work space plus buffer), and termination area, which returns traffic to its normal path.

A penetration-test index comparing a subgrade or base material's strength to that of a standard crushed-stone material (CBR = 100). Used to characterize subgrade support for flexible pavement design.

The key subgrade stiffness parameter in AASHTO and mechanistic-empirical pavement design methods, representing the elastic response of soil under repeated traffic loading. Higher Mr means stronger subgrade support.

Flexible (asphalt) pavement distributes load through layered materials in a cone-shaped stress pattern down to the subgrade. Rigid (concrete) pavement acts as a beam, spreading load over a wide area through slab bending, relying less on subgrade support.

A flexible pavement design index combining layer thickness, layer coefficients, and drainage coefficients: SN = a1D1 + a2D2m2 + a3D3m3. A higher required SN means a thicker or stronger pavement structure is needed for the design traffic and subgrade.

Q = CiA, where Q is peak runoff (cfs), C is the runoff coefficient (dimensionless, land-use dependent), i is rainfall intensity (in/hr) at the time of concentration, and A is drainage area (acres). Best suited to small drainage areas.

The time for runoff to travel from the hydraulically most distant point in a watershed to the point of interest (outlet). Used to select the design rainfall intensity in the Rational Method and other hydrology models.

V = (1.49/n) x R^(2/3) x S^(1/2), U.S. customary units, where V is flow velocity (ft/s), n is Manning's roughness coefficient, R is hydraulic radius (ft), and S is the channel or pipe slope (ft/ft). Used for open-channel and culvert flow.

Inlet control: capacity is limited by the inlet opening's ability to admit flow (headwater and inlet geometry govern). Outlet control: capacity is limited by the full culvert barrel plus tailwater and friction losses. Either mode can govern depending on flow conditions.

A stormwater facility that temporarily stores runoff and releases it at a controlled, reduced rate, mitigating peak-flow increases caused by development so downstream conveyance systems aren't overwhelmed.

Structural measures (e.g., bioretention, swales, sand filters) and non-structural measures (e.g., street sweeping, erosion control) used to mitigate runoff volume, rate, and pollutant load for water-quality protection.