Introduction to Transportation Engineering

Introduction to Transportation Planning and Engineering

• Transportation is the efficient movement of people and goods from one location to another to complete tasks.
• Transportation engineering is the application of engineering principles to transportation systems, including vehicles, infrastructure, safety, environmental impact, and energy usage.
• Transportation encompasses everything involved in moving people or goods from origin to destination.

Transportation System

• Transportation systems include land transportation (highways, rural, urban), air transportation (airports, domestic, international), water transportation (ports, harbors, ocean), rail transportation (railways, separated grades), and pipeline transportation (oil, gas, etc.).

Transportation Providers

• Hire systems are classified into:
  • Contract Carriers: provide service under individual contracts.
  • Common Carriers: provide scheduled service to all members of the public willing to pay.
• Mass transportation (or mass transit) refers to the common carriage of passengers (taxis, car rentals).

Urban Transportation Systems

• Urban freight distribution is primarily via highway subsystems (vans, trucks).
• Passenger transport is the main urban movement.
• Water transportation and air transportation are less suitable for urban travel, as opposed to land-based modes (heavy rail, light rail, buses).

Transportation Modes

• Highways are the most dominant transport mode globally, including the Philippines.
• Highway systems are used by private vehicles, truck lines, and bus lines for intercity and urban passenger transport and goods distribution.

Major Characteristics of Highway Systems

• High accessibility to destinations.
• Direct service with low travel times.
• Moderate line haul speeds and capacities.
• Moderate capital costs for physical facilities.
• Relatively cheap vehicles compared to other modes.
• High total investment in physical facilities and vehicles.
• High operating costs.
• High environmental impact, a significant concern for society.

Urban Transportation (Specific Modes)

• Trams (street cars): powered by overhead wires, share roadways with other vehicles, and operate on tracks.
• Light rail: electric-powered vehicles running on steel rails (metro), accessible from road surfaces or low platforms, may have exclusive rights-of-way alongside roads .
• Rapid rail transit (metro): underground tubes with exclusive rights-of-way provide high speeds and capacity.
• Para-transit: small passenger vehicles operating informally on a fare-paying basis, an alternative to regular bus services.

Traffic Flow, Speed and Density

• Traffic flow (q) is the number of vehicles passing a point in a time interval.
• Time headway = the time between successive vehicles at a point.
• Speed and flow are key indicators in traffic analysis.

Average Traffic Speed

• Time mean speed (u): the average speed of vehicles passing through a point.
• Space mean speed (us): the average speed of a group of vehicles over a specific distance or segment.

Traffic Density

• Traffic density (k) is the number of vehicles occupying some length of highway at a specific time.
• Spacing (s) is the distance between two vehicles' front bumpers.

Basic Traffic Stream Models

• Basic relationship: traffic flow equals speed (space mean speed) multiplied by density.
• Flow-density model: flow (q) is a function of density (k).
• Speed-density model: speed (u) is a function of density (k).
• Speed-flow model:: speed (u) is a function of flow (q).

Queuing Theory & Traffic Flow Analysis

• Queuing theory explores how arrivals and departures affect road capacity.
• Queue models describe the characteristics of waiting lines at toll booths (M/D/1, M/M/N Queues).

Analysis of Signalized Intersection

• Intersection types include T-intersections, cross intersections, Y-intersections, roundabouts, and others.
• Understanding signalized vs. unsignalized intersections is crucial for traffic analysis.
• Key signalized intersection elements include approach (lane group entering an intersection), cycle length, phase, signal indication, interval, green time, red time, yellow time, change interval, lost time, effective green time, effective red, saturation flow, major and minor street.
• Various signal timing types (e.g., pretimed, semi-actuated, fully actuated) affect intersection capacity.

Highway Capacity and Level-of-Service Analysis

• The Highway Capacity Manual (HCM) provides standardized methods for traffic operational performance and capacity utilization analysis.
• Level of service (LOS) represents a qualitative ranking of traffic operational conditions.
• Levels of service (A-F) for freeways and multilane highways quantify traffic conditions based on speed, density, freedom of maneuver, comfort, and psychological condition.

Freeway Segments and Base Conditions

• A basic freeway segment is a portion of a multilane divided highway with full access control, not affected by divergences or merges, with 2-or more lanes in each direction.
• Base conditions for freeway segments typically involve 12-ft lane widths, 6-ft right shoulders, 2-ft median lateral clearance, no obstructions or utility poles, no grade of more than 2%, and a driver population of predominantly familiar roadway users.

Service Measure

• Density (pc/mi/ln) is a key service measure for basic freeway segments. This reflects the relative mobility of individual vehicles within a traffic stream.

Peak Hour Factor

• PHF is a factor to determine high volume and peak-hour flow rate.

Heavy Vehicle Adjustment Factors

• Er (trucks & buses), ER (RVs): factors to calculate the impact of heavy vehicles.

Driver Population Adjustment Factor

• fp: driver population adjustment factor accounts for driver population composition, typically ranging from 0.85 to 1.00.

Travel-Demand Forecasting

• Travel demand and traffic forecasting involves predicting travel patterns through accurate regional economic forecasts and forecasting of highway user social/behavioral patterns.
• Models used for prediction include trip generation, mode/destination choice, and highway route choice.

Accident Analysis

• Accident analysis involves defining and measuring road safety, which includes fatal accidents (deaths within 30 days), fatalities (deaths at the scene), serious accidents, slight injuries, and property damage.
• Accident rates per population, per registered vehicles, and rates at intersections, are all calculated metrics in this analysis.

Explore the fundamental concepts of transportation planning and engineering. This quiz covers essential topics such as transportation systems, efficiency, and various transportation providers, enabling you to understand the complex network that facilitates movement in society.