HIGHWAY DESIGN REVIEWER

Transportation

“Circulatory System” & Backbone of the society

Transportation Engineering

provides safe and efficient movement of people and goods

Types of Transportation Engineering

• Port and Harbor Engineering

• Highway and Traffic Engineering

• Railway Engineering

• Airport and Engineering

Scopes of Highway Engineering

1. Planning

2. Geometric Design

3. Pavement Engineering

4. Traffic Engineering

5. Construction, Maintenance ang Management

Goals of Transportation Engineering

1. Provide a high Level of Service (LOS) by minimizing travel time and delays

2. Provide a high Level of Safety (LOS) by minimizing accident and harmful effects to environment

Economic Growth

• provide connectivity between regions

• leads to increased trade, commerce and economic activity

Regional Development

improve access to remote and undeveloped areas

Improved Transportation

• enables faster and more efficient transportation of goods and people

• reduce travel time and cost

Safety

signage, signals, and safety measures reduce accidents and fatalities

Environment

helps minimize air and noise pollution

Highway Fragmentation

negative impact roads have on ecosystem

Classification of Roads

1. Expressways

2. Freeway

3. Arterial Road

4. Collector Road

5. Local Raod

Expressways

generally with grade separation at major intersections

• Full control of access

• Partial control of access

Freeway

• highspeed, fully-controlled-access highway with no at-grade crossing or intersections

• have multiple lanes in each intersections

Arterial Road

• with intersections and signal lights

• connection of other roads to expressways

Collector Road

• collects/connect local road to arterial or freeway

• provides access to residential and commercial areas

Local Road

• connects residential and other local roads to main road(collector road)

• provides access to properties along the road

Road Patterns

1. Rectangular (or block) pattern

2. Radial (or star) & block pattern

3. Radial (or star) & circular pattern

4. Radial (or star) & grid pattern

5. Hexagonal

Rectangular (or Block) Pattern

Radial (or Star) & Block Pattern

Radial (or Star) & Circular Pattern

Radial (or Star) & Grid Pattern

Hexagonal

Types of Planning Studies

1. Engineering Studies

2. Economic Studies

3. Financial Studies

4. Traffic Road Use Studies

Engineering Studies

assess technical feasibility of proposed project/infrastructure

• site investigations

• geotechnical surveys

• structural design and parameters

• cost estimate based on design specifications

Economic Studies

overall viability of a project & focus on how the project affects society at large

• economic internal rate of return (EIIR)

• cost-benefit analysis

• socioeconomic impact

• environmental & social considerations

Financial Studies

monetary aspects of a project

• financial internal rate of return (FIRR)

• project funding sources & structures

• revenue forecasting & affordability

• financial risk analysis

Traffic Road & Studies

how roads are currently used and predict future traffic patterns

• traffic counts & vehicle classifications

• peak hour studies

• origin-destination surveys

• road safety & capacity analysis

Alignment

laying out of the centerline of a proposed highway on the ground

Requirements of Highway Alignment

1. Directness

2. Ease of Construction, Maintenance & Operation

3. Safety

4. Economy

5. Special Considerations

Horizontal Alignment

alignment of highway/roadway in horizontal plane

Vertical Alignment

change in gradient calls for curves in vertical plane

Horizontal Curve

for smoothening change of direction

Vertical Curve

for smoothening change of longitudinal gradients

Stages of Engineering Surveys for Highway Location

1. Map Study

2. Preliminary Survey

3. Final Location & Detailed Survey

Map Study

• to conduct initial evaluation using topographic & thematic maps

• to identify possible corridors for highway

• helps ruling out unsuitable areas

Preliminary Survey

• to inspect shortlisted routes on the ground

• involves reconnaissance survey & basic field investigation

Final Location & Detailed Survey

• to finalize the highway alignment

• detailed survey is conducted along chosen route

Highway Economics

• involves evaluating cost & benefits associated with highway projects

• to maximize the economic benefits to society while minimizing cost

PPPs (Public - Private Partnerships)

helps mobilize additional resources & improve efficiency

Cost Components in Highway Projects

1. Capital Cost

2. Maintenance & Operating Cost

3. User Cost

4. External Cost

Capital Cost

one-time expenditures

Maintenance & Operating Costs

keep the highway in good condition & endure safety

User Costs

incurred by road users

• vehicle operating costs

• travel time costs

• accident costs

External Costs

unintended consequences

• environmental degradation

• social impacts

Economic Evaluation Methods

1. Cost - Benefit Analysis (CBA)

2. Life Cycle Cost Analysis (LCCA)

3. Shadow Pricing & Economic Costs

4. Sensitivity & Risks Analysis

Costs - Benefit Analysis (CBA)

a systematic approach to comparing the benefits & costs of a project

Components of Cost-Benefit Analysis (CBA)

• Net Present Value (NPV)

• Benefit-Costs Ratio (BCR)

• Internal Rate of Return (IRR)

• Financial Benefit (FB)

• Non-Financial Benefit (NFB)

Life Cycle Costs Analysis (LCCA)

economic evaluation method that evaluates total costs of ownership over a highway’s lifespan

Components of Life Cycle Cost Analysis (LCCA)

• initial construction costs

• routine & periodic maintenance

• rehab or replacement costs

• salvage value

Shadow Pricing & Economic Costs

economic evaluation method that converts financial costs to economic values using conversion factors to adjust for market distortions such as taxes or subsidies

Sensitivity & Risks Analysis

economic evaluation method that tests how results change with variations in key assumptions

Components of Highway Project Financing

1. Public Sector

2. Private Sector

Public Sector

highway project financing sector that financing ensures social equity by funding roads that may not be financially viable but have high economic & social benefits

Private Sector

highway project financing sector that is mobilized through PPPs

Common PPP Project Model

1. Build - Operate - Transfer (BOT)

2. Build - Own - Operate - Transfer (BOOT)

3. Build - Own - Operate (BOO)

4. Management Agreement / Operations & Maintenance (O&M)

5. Design - Build - Finance - Operate - Maintain (DBFOM)

6. Design - Build - Lease (DBL)

Highway Design

Designed to provide safe roads for all road users

“Man is the reference standard”

roads must be adapted to the limitations of human capacity

Principles of Highway Design

1. Road Characteristics

2. Driver Characteristics

3. Vehicle Characteristics

Road Characteristics

1. Consistency

2. Highway Capacity

3. Average Annual Daily Traffic (AADT or ADT)

4. Cross-section of Typical Highway

5. Pavement

6. Cross Slope / Crossfall

7. Road Shoulder

8. Cut or Fill Slope

9. Interchanges

10. Highway Intersection at Grade

Road Shoulder

portion of roadway between the edge of traffic lane where vehicle can stop when disabled

Driver Characteristics

1. Human Sensory Process

2. Driver Perception - Reaction Time (PIEV Time)

3. Visual Acuity

4. Lateral Displacement

Human Sensory Process

information received to process

Types of Human Sensory Process

1. Visual (Sight)

2. Kinesthetic (Movement)

3. Vestibular (Equilibrium)

4. Auditory (Hearing)

Perception

detection

Intellection

Identification

Emotion

Decision

Volition

Response

Visual Acuity

sharpness with which person can see the object

Lateral Displacement

driver’s tendency to displace laterally away from the object

2 Primary Opposing Forces

1. Tractive Effort

2. Resistance

Tractive Effort

force available at roadway to perform at roadwork

Resistance

force impending at vehicle motion

3 Major Vehicle Resistance

1. Aerodynamic Resistance

2. Rolling Resistance

3. Grade Resistance

Aerodynamic Resistance

resistance force that can have significant impact on vehicle performance

Rolling Resistance

resistance generated from vehicles internal mechanical friction, and pneumatic tires and interaction with roadway surface

Grade Resistance

simply gravitational force acting on vehicle

Inertia

tendency of vehicle to resist acceleration

Curve

• force required to cause vehicle to move along curve

• function of curvature and speed

Vehicle Maximum Tractive Effort

results in spinning tires and does not overcome resistance or accelerate the vehicle

Vertical Alignment

establishing the transition of roadway elevation between two grade

Types of Vertical Alignment

1. Crest Vertical Curve

2. Sag Vertical Curve

Stopping Sight Distance (SSD)

sufficient sight distance to allow them to safely stop their vehicles

Breaking Distance

distance needed to stop vehicle from instant break application begins

Height of driver’s eye through passenger vehicles

3.50ft (1.08m) above road surface

Height of driver’s eye through truck driver

7.60ft (2.33m) above road surface

Horizontal Alignment

directional transitional between two straight sections of roadway (cornering capabilities of the vehicle)

Simple Curve

Compound Curve

Reverse Curve

Spiral Curve

Passing Sight Distance (PSD)

shortest distance required for a vehicle to pass a vehicle travelling in the same direction

Superelevation

intentional tilting of road surface on a curve (banking)