CSS-Transit flashcards

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

Headway-frequency relationship

Headway in minutes equals 60 divided by departures per hour. A 10-minute headway means six vehicles per hour in each direction on the route.

Fleet size formula

Vehicles needed equals cycle time divided by headway, rounded up, plus a spare ratio. Cycle time includes round-trip running time and terminal recovery time.

Recovery time

Scheduled slack at terminals, typically 10 to 20 percent of one-way running time, that lets operators recover from delay and use restrooms without disrupting the next trip.

On-time performance

Percentage of trips departing or arriving within the agency's defined window, often zero to five minutes late at timepoints. Early departures usually count as failures.

Load factor

Passenger boardings divided by seats offered, or passengers divided by capacity. Planners size vehicles to the peak load point rather than the route average.

Revenue versus vehicle hours

Revenue hours are hours in passenger service; vehicle hours include deadheading and pull-in. Cost per revenue hour is the common efficiency benchmark.

Dwell time

Time a vehicle stands at a stop for boarding and alighting. It grows with passenger volume and slows with on-board fare payment, affecting schedule reliability.

Stop spacing tradeoff

Closer stops improve access but reduce average speed and increase travel time. Local service uses roughly 400 meters; express and BRT use 800 to 1,600 meters.

SMS four pillars

Safety Management Systems rest on Safety Policy, Safety Risk Management, Safety Assurance, and Safety Promotion. Federal transit rules require an Agency Safety Plan built on these pillars.

Hazard versus risk

A hazard is a condition with potential to cause harm. Risk combines severity and likelihood, ranked on a matrix before selecting controls.

Hierarchy of controls

From most to least effective: elimination, substitution, engineering controls, administrative controls and procedures, then personal protective equipment. Use the highest feasible level.

Leading and lagging indicators

Leading indicators predict harm, such as hazard reports and near misses. Lagging indicators measure outcomes, such as collisions and injuries per million vehicle miles.

Agency Safety Plan

A federally required document describing safety objectives, risk management, and assurance processes, reviewed annually and supported by a safety committee or equivalent.

Safety versus security

Safety addresses unintentional harm from operations and conditions. Security addresses intentional acts such as assault, theft, and terrorism, using design and surveillance countermeasures.

Emergency management phases

Mitigation, preparedness, response, and recovery. Exercises progress from tabletop discussions to functional drills to full-scale simulations with partner agencies.

Sealed bid procurement

A formal advertised method awarding to the lowest responsive, responsible bidder when specifications are clearly defined. Price drives selection and bids are opened publicly.

Competitive proposal procurement

A method used when technical approach matters, such as technology or design services. Proposals are scored on stated criteria and price, then negotiations may follow.

Buy America

Federal requirement that transit rolling stock have final assembly in the United States, meet domestic content thresholds, and use domestic steel and iron.

DBE program

Disadvantaged Business Enterprise rules require recipients to set an overall participation goal, use race-neutral and race-conscious measures, and monitor prompt payment to subcontractors.

ADA complementary paratransit

Shared-ride service for people unable to use fixed-route transit, required within three-quarters of a mile of routes, on the same days and hours, with comparable response time.

NEPA environmental classes

Projects fall into a Categorical Exclusion, an Environmental Assessment leading to a Finding of No Significant Impact, or an Environmental Impact Statement for significant effects.

Bus model testing

New bus models must complete standardized testing at a federally designated facility before an agency may buy them with federal funds, covering safety and durability.

CAD/AVL

Computer-aided dispatch with automatic vehicle location tracks vehicles in real time, supports service control, and feeds arrival predictions to passenger information systems.

Automatic passenger counter

Sensors that count boardings and alightings by stop. Data supports ridership reporting, load analysis, and schedule adjustments, and should be reconciled with farebox data.

Transit signal priority

Roadside and vehicle systems request extended or early green for buses at intersections. Conditional priority limits requests to late vehicles to protect cross-street traffic.

Open-loop fare payment

Riders tap contactless bank cards or mobile wallets instead of agency-issued media. Account-based systems apply fare rules and caps centrally and reduce agency payment scope.

GTFS and GTFS-Realtime

GTFS is the static schedule specification of stops, routes, trips, and times. GTFS-Realtime streams trip updates, vehicle positions, and service alerts for apps.

OT and IT segmentation

Separating operational technology such as vehicle and signal systems from business networks limits cyberattack spread. Pair with patching, monitoring, and multi-factor authentication.

Predictive maintenance

Using telematics, fault codes, and sensor trends to schedule repairs before failures occur, reducing road calls and unscheduled vehicle downtime.

Operator staffing formula

Operators required equals annual vehicle service hours divided by average paid hours per operator, then increased for absenteeism, training, and vacation coverage.

Extra board

A pool of operators or mechanics covering absences, vacations, and open work. Its size reflects absenteeism rates and the agency's service reliability targets.

Run cutting and picks

Run cutting divides vehicle work into operator assignments respecting labor rules. Seniority-based picks let operators choose assignments in order of seniority.