Free RSP Exam Flashcards

Nominal safety concerns compliance with applicable design standards, warrants and guidelines. Substantive safety concerns actual or expected crash frequency and severity. Compliance is useful, but does not guarantee low crash risk: standards-compliant geometry can still encourage unsafe speeds or create conflicts. Conversely, a nonstandard feature is not by itself proof of poor crash performance. Assess the applicable requirements and the observed or predicted safety outcomes together; a compliance check and a crash-risk assessment answer different questions.

Developed by William Haddon Jr., the Haddon Matrix is a 3×3 (or 3×4) epidemiological grid crossing three temporal crash phases (Pre-Crash, Crash, Post-Crash) with contributing factors (Human, Vehicle/Equipment, and Physical/Social Environment). It shifts analysis beyond pre-crash driver blame by identifying opportunities to prevent crashes, manage impact energy during a collision, and improve survivability through post-crash care.

FHWA lists six principles: deaths and serious injuries are unacceptable; humans make mistakes; humans are vulnerable; responsibility is shared; safety is proactive; and redundancy is crucial. These concern the way a system should be designed and managed, rather than five separate infrastructure treatments. Anticipate errors and limits of human tolerance, distribute responsibility across system designers, operators and users, and provide overlapping protections so one failure does not automatically result in fatal or serious injury.

Safe Road Users, Safe Vehicles, Safe Speeds, Safe Roads, and Post-Crash Care. Working together, these five elements create redundant layers of protection that manage kinetic energy so human errors do not result in fatal or serious injuries.

Vision Zero (originating in Sweden in 1997) is the ethical and policy commitment that no loss of life or serious injury is acceptable in the road transport system. Toward Zero Deaths (TZD) is the U.S. national highway safety strategy framework promoting that shared vision and safety culture. The Safe System Approach provides the operational and engineering methodology—managing kinetic energy across redundant system layers—used to achieve Vision Zero and TZD.

Each slice represents a protective layer, such as safe speeds, roadway design, vehicle crashworthiness or post-crash response; holes represent weaknesses or failures. The model illustrates how several weaknesses can combine to let a hazard pass through the system, and why redundancy matters. It is a conceptual model, not a literal rule that every fatal crash requires an identifiable hole in every possible layer. Improving one layer can reduce risk, while maintaining the other layers protects against imperfect performance.

Kinetic energy increases with the square of speed (KE = ½mv²). A modest increase in travel speed simultaneously lengthens braking distance and multiplies the energy that must be dissipated during impact. Once crash forces exceed human biomechanical tolerance—especially for unshielded pedestrians, bicyclists, and motorcyclists—the probability of fatal or serious injury rises sharply.

The traditional 4 E's are Engineering, Enforcement, Education, and Emergency Medical Services (EMS). Many contemporary safety plans expand this multidisciplinary model to include Equity (addressing disproportionate injury burdens across underserved communities) and Evaluation (measuring actual crash and injury outcomes).

NHTSA’s March 2018 summary of the 2005–2007 NMVCCS assigned a driver-related critical reason in an estimated 94% of the qualified light-vehicle crashes studied. A critical reason describes the immediate reason for the critical pre-crash event, often the last failure in an event chain. NHTSA explicitly says this is not the cause of the crash or an assignment of fault. The historical estimate is not a current universal percentage for all crashes; roadway, vehicle and environmental factors can interact with driver errors.

Crash counts measure collision events; injured-person counts measure individual outcomes, so one crash can injure several people. A zero pedestrian-crash count can reflect low pedestrian exposure, chance, incomplete reporting or a genuinely low-risk setting. An intimidating crossing may also discourage walking or force lengthy detours. Check pedestrian demand, speeds, crossing opportunities, accessibility, conflicts and exposure before interpreting the count. Suppressed demand is a possible explanation to investigate, not something proved by every zero-crash record.

Economic crash costs include monetary losses such as medical care, emergency response, property damage, congestion and lost productivity. Comprehensive costs also account for lost quality of life, using an explicitly defined valuation framework. In safety appraisal, use consistent severity categories, price year and valuation conventions. A value of statistical life represents willingness to pay for small risk reductions, not a compensation price for a specific person. Do not automatically add a full VSL estimate to all human-capital components if the chosen method already includes them; that can double count benefits.

KABCO is a police-reported functional injury-severity classification: K fatal injury, A suspected serious injury, B suspected minor injury, C possible injury, and O no apparent injury. A fatal crash reporting rule generally uses death within 30 days; an initial scene assessment can be updated. AIS is a clinical anatomical injury-severity system based on diagnosed injuries, with levels from 1 minor to 6 maximal. Suspected scene categories and diagnosed clinical injury scores are not interchangeable, and no apparent injury at the scene is not proof that no injury is later diagnosed.

FARS (Fatality Analysis Reporting System) is NHTSA's nationwide census of fatal crashes on public trafficways resulting in death within 30 days. CRSS (Crash Report Sampling System) is a nationally representative probability sample of police-reported fatal, injury, and PDO crashes. MMUCC sets uniform crash-report data elements; MIRE sets roadway/traffic inventory elements; and HSIS (Highway Safety Information System) is FHWA's multistate linked crash-and-roadway research database.

Timeliness (how quickly records are available), Accuracy (freedom from coding or location errors), Completeness (coverage of all reportable crashes and required fields, noting that PDO and non-motorized crashes are frequently underreported), Uniformity (adherence to standard definitions like MMUCC), Integration (ability to link crash, roadway, citation, and EMS/hospital databases), and Accessibility (ease of authorized retrieval and analysis).

Divide the period’s crash count by total entering-vehicle exposure and multiply by 1,000,000. If average daily entering volume DEV is treated as constant over N years of 365 days, R = C × 10⁶ / (365 × N × DEV). DEV sums vehicles entering from all approaches, not entering plus exiting vehicles. For variable volumes or a period containing leap days, use the corresponding summed exposure. This is a conceptual worked formula for study; TPCB states that the qualitative RSP1 exam requires no computations.

Divide crash count C by total vehicle-miles of exposure, then multiply by 100,000,000. With constant AADT, segment length L miles and N years of 365 days, R = C × 10⁸ / (365 × N × AADT × L). Use actual period exposure when volumes or day counts differ. A rate describes crashes relative to exposure; comparing rates alone can mislead when the crash–volume relationship is nonlinear or facility types differ. It also does not automatically account for severity, random variation or regression to the mean.

A Poisson model has equal conditional mean and variance. Crash counts across sites often show more variation than that assumption allows, because of differences not fully explained by the model. A negative binomial model includes an overdispersion parameter to represent extra variation and is widely used in Highway Safety Manual predictive modeling. It is a common modeling choice rather than the definition of every safety performance function; suitability depends on the data, facility type, assumptions and model validation.

A safety performance function (SPF) estimates average crash frequency for a defined facility type using explanatory variables such as traffic volume and, for segments, length. Particular HSM models use specified base conditions and adjustment procedures. Before applying a model elsewhere, check its facility, crash-type and exposure scope and its calibration guidance. A local calibration factor can compare aggregate observed crashes with aggregate model predictions for suitable reference sites. Not every SPF uses an identical distribution, list of variables or calibration procedure.

Regression to the mean is the tendency for an unusually extreme observation to be followed by observations closer to the long-term mean when random variation contributed to that extreme. A high-crash period does not guarantee that a particular site’s next count will fall. However, selecting treatment sites solely because of short-term spikes can make a naive before–after comparison overstate the treatment effect when some of the decline would have occurred without treatment. Use an appropriate model or evaluation design to address this selection bias.

Empirical Bayes (EB) combines a suitable reference-group prediction with observed site crashes to estimate the site’s long-term expected crash frequency. A weighted representation is N_expected = w × N_predicted + (1 − w) × N_observed, with 0 ≤ w ≤ 1 and all quantities expressed for compatible periods. The weight depends on model uncertainty and the information in the observations; particular HSM models define it using their own dispersion and period conventions. EB addresses regression-to-the-mean bias when correctly applied, but cannot repair an unsuitable model or poor data automatically.

CMF = 1 - (CRF / 100), or CRF (%) = (1 - CMF) × 100. A CMF of 0.70 corresponds to a CRF of 30% (an expected 30% reduction in target crashes), whereas a CMF > 1.0 indicates an expected crash increase. In the FHWA CMF Clearinghouse, the 1-to-5 star rating measures the statistical quality and rigor of the research study—not the magnitude of crash reduction (unlike NHTSA's Countermeasures That Work, where stars indicate behavioral intervention effectiveness).

In Alexander and Lunenfeld's positive guidance model, the three levels are: (1) Control (micro-performance steering, braking, and speed modulation), (2) Guidance (selecting safe speed, lane position, and following gaps relative to traffic and geometry), and (3) Navigation (macro-performance route planning and direction finding). Under the Primacy Principle, Control and Guidance information must take precedence over Navigation signs when hazards compete for driver attention.

PIEV describes perception of a stimulus, interpretation of the hazard, decision on a response and initiation of the physical action. The familiar AASHTO stopping-sight-distance design perception–reaction time is 2.5 seconds; it is a design assumption, not a measured duration guaranteed for every driver or every situation. Driver expectancy, visibility, complexity, impairment and distraction affect actual responses. Do not conclude that each conceptual stage has a fixed duration or that their sum must equal 2.5 seconds in real driving.

Positive Guidance combines highway design and traffic control devices to give drivers clear, unambiguous information about hazards and the safe speed/path when needed. 'A priori' expectancies are long-term expectations formed from life-long driving experience (e.g., freeway exits are on the right), whereas 'ad hoc' expectancies are short-term expectations built while driving a specific corridor (e.g., a series of gentle curves). Violating an expectancy can increase response time and error risk, depending on the situation.

Central vision supports fine detail and sign reading. Peripheral vision helps detect motion and changes outside the point of fixation. Contrast sensitivity concerns distinguishing an object from its background; low illumination, glare, weather and some age-related changes can impair detection. A driver can have adequate high-contrast visual acuity yet struggle to see a dark pedestrian at night. If the available hazard-detection distance is shorter than the distance needed to stop, the driver can overdrive the headlights. Consider the visibility task and conditions rather than one universal angular or age cutoff.

Very low workload in a monotonous setting can reduce vigilance or contribute to fatigue; very high workload can exceed a driver’s capacity to process competing information and make timely decisions. The inverted-U model is a useful conceptual illustration, not a universal measured curve for every driver and task. Design and traffic control should support timely detection, understandable choices and adequate response time, avoiding both unnecessary complexity and reliance on sustained perfect attention.

Distraction can be visual (eyes away), manual (hands away) or cognitive (attention away). Texting often combines all three. A hands-free phone or voice interaction can still compete for attention and impair hazard detection or response even when hands remain on the wheel and eyes face forward. The size of the effect depends on the task, driver and traffic conditions; hands-free does not by itself establish that an interaction is safe. Separate the source of distraction from its observed effects on driving performance.

Deterrence theory considers certainty of detection, swiftness of consequences and severity of punishment. In traffic-safety programs, credible and sustained enforcement with publicity can increase the perceived likelihood of being caught; simply raising a penalty does not ensure behavior change. Certainty is often especially influential, but effects depend on the behavior and program context. Enforcement should be evaluated alongside safe road design, speeds, access and other protections rather than treated as a substitute for them.

Young/novice drivers face elevated crash rates due to immaturity, risk-taking, peer-passenger distraction, nighttime driving, and underdeveloped hazard anticipation (addressed by Graduated Driver Licensing [GDL] restrictions). Some older drivers self-regulate or avoid difficult conditions. Age-associated changes in vision, processing, gap judgment and physical fragility can increase risk, but vary substantially between individuals; assess functional needs rather than treating age alone as impairment.

Users respond to environmental cues as well as signs and rules. A wider or more forgiving-looking road can sometimes encourage higher operating speeds, partially offsetting an intended safety gain; this is a possible adaptation, not an inevitable result of every improvement. A self-explaining road uses consistent geometry and traffic control to communicate the intended speed and function. Select context-appropriate treatments and assess the resulting operating behavior, including sight distance, roadside safety, accessibility and the needs of every road user.

MUTCD 11th Edition, including Revision 1, Section 4I.06 gives guidance for pedestrian clearance time using 3.5 ft/s from the curb to the far side of the traveled way or applicable median. A lower speed should be considered where slower pedestrians or wheelchair users routinely use the crossing. A separate guidance check uses 3 ft/s for the total WALK plus clearance interval, measured from the detector or specified starting location. These are different intervals and starting points; 3 ft/s is not merely an optional replacement label for the clearance check.

(1) Network Screening (identifying sites or corridors with promise for crash reduction), (2) Diagnosis (investigating crash patterns, site conditions, and contributing mechanisms), (3) Select Countermeasures (matching proven treatments to diagnosed causes), (4) Economic Appraisal (comparing monetized crash benefits to project costs), (5) Prioritize Projects (optimizing project selection within budget constraints), and (6) Safety Effectiveness Evaluation (measuring post-implementation results).

Hot-spot screening is reactive, focusing on individual intersections or segments with high historical crash concentrations. The Systemic Safety Approach is proactive: it analyzes severe crashes across an entire network to identify common physical and operational risk characteristics (e.g., rural curves with narrow shoulders or unsignalized multilane crosswalks) and deploys low-cost, proven countermeasures across many matching sites—even those with zero recent crashes.

This network-screening measure compares the site’s EB-estimated expected average crash frequency with the SPF-predicted average for a comparable facility: excess = expected − predicted, using compatible crash types and periods. A positive value suggests more crashes than the reference prediction and can help identify sites for further diagnosis. It does not by itself prove a specific hazard or identify the best treatment. Model validity, severity, uncertainty, data quality and the screening objective matter; no single measure is universally best for every network.

A Collision Diagram schematically maps the location, direction of travel, maneuver, severity, time of day, and pavement condition of individual crashes at a site to reveal recurring patterns (e.g., left-turn, right-angle, or wet-weather rear-end clusters). A Condition Diagram maps the physical site features—lane geometry, sight obstructions, grades, signs, signals, and roadside hazards—allowing analysts to connect crash patterns to physical or operational causes.

Surrogate measures include traffic conflicts, time to collision, post-encroachment time, speeds, lane departures and yielding behavior. They can reveal mechanisms and provide earlier feedback than rare injury crashes. Their relationship to actual crash or injury risk must be justified for the setting and measurement method. A change in a surrogate is not automatically an equal percentage change in fatal crashes; use validated interpretation and later outcome monitoring when evaluating a countermeasure.

If applicable countermeasures address sufficiently independent effects for the same target crash population, one approach is CMF_combined = CMF₁ × CMF₂. For example, 0.80 × 0.90 = 0.72, representing an estimated 28% reduction from the compatible baseline. Check crash type, severity, facility, study conditions and dependence before using that method. Overlapping effects can cause multiplication to overestimate benefits; use a supported combined-treatment estimate or another justified method where appropriate. Two published CMFs alone do not establish independence.

A modern roundabout reduces vehicle speeds and replaces crossing movements with lower-angle merging and diverging movements. A conventional four-leg, single-lane vehicle-conflict illustration falls from 32 to 8 conflict points, but that is not every layout or a count of all pedestrian and bicycle conflicts. A road diet can separate left turns from through traffic and provide space for other users. Published crash-reduction estimates depend on the conversion, original control, traffic and target severity; they are not universal guarantees or substitutes for feasibility and safety assessment.

An LPI typically gives pedestrians a 3–7-second WALK head start before adjacent parallel traffic receives a green indication, making crossing pedestrians visible in the crosswalk before vehicles turn. RRFBs use pedestrian-actuated irregular LED flash patterns at uncontrolled crosswalks to increase driver yielding. PHBs (HAWKs) remain dark until activated, then cycle through flashing yellow, solid yellow, solid red (requiring drivers to stop), and alternating flashing red on high-speed or wide multilane corridors.

Consider removing, redesigning or relocating a hazard before reducing impact severity with breakaway hardware, shielding with a barrier or crash cushion, or delineating it. Barriers also present collision risk, so compare them with the unshielded hazard. A foreslope of 1V:4H or flatter is generally recoverable; slopes steeper than 1V:4H through 1V:3H are generally traversable but nonrecoverable; steeper than 1V:3H is critical. These categories also depend on surface and shape: a nominal slope ratio alone does not establish a safe recovery area.

A road safety audit (RSA) is a formal safety-performance examination of an existing or future road or intersection by an independent, multidisciplinary team. It considers potential safety issues for all users, beyond compliance with design standards. In FHWA’s RSA process, the owner or design team prepares a formal written response stating the action proposed for each concern and explaining decisions not to act. This is a defined process step; whether a particular audit creates a legal obligation depends on the applicable law, contract or adopted agency policy.

BCR = present value of benefits / present value of costs, and NPV = present value of benefits − present value of costs. With positive costs and consistent scope, BCR > 1 corresponds to NPV > 0; BCR = 1 and NPV = 0 are break-even boundaries. Estimate lifecycle costs and compatible crash-reduction benefits using an explicit discount rate and horizon. For mutually exclusive alternatives, use an appropriate incremental comparison or NPV analysis with comparable scope; selecting the highest standalone BCR need not maximize net benefits under the decision constraints.

A properly specified EB before–after evaluation can address regression to the mean while accounting for traffic and time-related changes. A comparison-group before–after study uses suitable untreated sites to estimate general changes, but does not automatically remove selection-related regression to the mean. Cross-sectional studies compare different sites and must address differences between treated and untreated locations. Each approach depends on data quality and assumptions; a method’s name alone does not establish causation or remove every source of confounding.

A strategic highway safety plan (SHSP) is a statewide, data-driven, multidisciplinary plan developed by the State DOT with safety stakeholders. It addresses fatal and serious-injury risks for all road users on public roads and establishes emphasis areas and strategies that guide other safety plans and programs. Under 23 CFR 924.9(a)(3)(i), an update must be completed no later than five years after the previous approved version. Distinguish that regulatory update boundary from annual program implementation and performance monitoring.

HSIP (23 U.S.C. 148) is a core federal-aid program whose purpose is to achieve a significant reduction in traffic fatalities and serious injuries on ALL public roads—explicitly including county, municipal, and tribal roads not owned by the State DOT. Projects funded with HSIP dollars must address a highway safety problem, be supported by crash/risk data, and be consistent with the state's SHSP (alongside dedicated set-asides such as the Railway-Highway Crossings program).

A local road safety plan translates crash patterns, systemic risk factors and community priorities into actions for a local network. An SS4A comprehensive safety action plan similarly connects leadership commitment, analysis, engagement, strategies and progress monitoring to reducing roadway deaths and serious injuries. A plan can help prepare projects and coordinate funding, but does not itself guarantee a grant award or prove that every listed project is eligible. Apply the current program notice, deadlines and project-specific criteria when seeking funding.

The five HSIP performance measures are the number of fatalities, fatality rate, number of serious injuries, serious-injury rate, and combined number of non-motorized fatalities and non-motorized serious injuries. Each is based on a five-year rolling average. The two rates use fatalities or serious injuries per 100 million vehicle-miles traveled; the fifth measure is a combined count, not a rate. These defined performance measures differ from a particular site’s crash rate and from the separately coordinated target-setting process.

While FHWA's HSIP primarily funds roadway infrastructure and systemic engineering improvements through State DOTs, NHTSA's Section 402 (State and Community Highway Safety Grant Program) and Section 405 (National Priority Safety Programs) are administered through State Highway Safety Offices (SHSOs) via the Highway Safety Plan (HSP) to fund behavioral countermeasures—such as impaired driving enforcement, occupant protection, speed enforcement, motorcycle safety, and state traffic records systems.

Complete Streets policies direct agencies to routinely plan, design, operate, and maintain roadways for safe, accessible travel by all users—pedestrians, bicyclists, transit riders, motorists, older adults, and people with disabilities—during ordinary resurfacing and reconstruction projects rather than treating multimodal safety as an optional add-on. Safe Routes to School (SRTS) combines infrastructure improvements (sidewalks, crosswalks, traffic calming) with education and encouragement around schools.

Traffic Safety Culture is the shared set of values, beliefs, and social norms that determine how an organization or community prioritizes road safety relative to competing goals like travel speed or cost. Internal organizational culture—led by executive champions and multidisciplinary teams—shapes agency policies, design standards, and resource allocation, while external public safety culture shapes road-user norms around seat belt use, sober driving, and speed compliance.