Highway Engineering

In Highway Engineering, we studied a total of five chapters, which are as follows:

• Chapter 1: Highway Engineering- Introduction
• Chapter 2: Geometric Design
• Chapter 3: Traffic Engineering
• Chapter 4: Pavement Design
• Chapter 5: Highway Material & Construction

  Highway Engineering- Introduction  

Introduction Of Transportation, Different Modes of Transportation: Railways Transportation, Water Transportation, Air Transportation, Road Transportation. Highway, Express Highway, Characteristics of Road Transport, Importance of Roads in India

Development of Road: 1. Roman Road, 2. Tesaguet Construction, 3. Telford Construction, 4. Macadam Road. 
Development of Roads In India: Mr. Jayakar Committee, Comparison Between Various Road Development Plans

Classification of Road: 1. Based on the duration of their use- All Weather Road, Fair Weather Road.  2. Based on traffic volume- Light Traffic Roads, Medium Traffic Roads, High Traffic Roads. 3. Based on location and function- National Highways (NH), State Highways (SH), Major District Roads (MDR), Other District Roads (ODR), Village Road (VR). Types of Road Patterns

Engineering Surveys For Highway Alignment: MAP Study, Reconnaissance, Preliminary Survey, Detailed Survey

Maximum Saturation System / Utility Factor System

  Geometric Design  

Geometric Design of Highway- For designing Highway elements, the following factors are considered: A. Topography or Terrain, B. Design Speed, C. Traffic Factor, D. Design Hourly Volume & Capacity, and E. Environmental Factor. 

Cross Section Elements: Pavement Surface Characteristic– (i) Skid and Slip, (ii) Friction- (A) Longitudinal Friction, (B) Lateral or Transverse Friction, (iii) Unevenness Index, (iv) Light Reflecting Characteristic, (v) Drainage. Camber / Cross- Slope, Width of Pavement or Carriageway, Divider /Medians / Traffic separators, Kerb– 1. Low or Mountable type Kerb, 2. Semi- Barrier type Kerb, 3. Barrier type kerb. Shoulder, Road Margin, Roadway / Width of Formation, Right of Way / Road Land. 

Sight Distance
Sight distance on a highway depends upon the following factors: 1. Total Reaction Time of Driver, 2. Design Speed, 3. Braking Efficiency, 4. Frictional Resistance Between Road and Tyres, 5. Gradient of Road (If Any).
Sight distances are of the following types: 1. Stopping Sight Distance (SSD): (I). Lag Distance (LL), (II). Braking Distance (LB).  2. Overtaking Sight Distance (OSD): Factors affecting OSD, Analysis of OSD. 3. Intermediate Sight Distance (ISD), Space Headway (s), 4. Sight distance at Intersections .

Curve: Advantages of Curves, Factors Affecting the Design of Curves, Type of Curves.

Design of Horizontal Alignment, Design Speed, Horizontal Curve- 1. Overturning the vehicle, 2. Lateral Skidding of the Vehicle.
Superelevation⇒ Analysis for Expression of Super-elevation, Equilibrium Superelevation, Superelevation As Per IRC– 1. Maximum Superelevation 2. The minimum superelevation.  Design of  Superelevation, Method of Obtaining Superelevation⇒ i) Elimination of the crown of the cambered section, ii) Rotation of pavement to attain full super-elevation.
Radius of Horizontal Curve⇒ 1. Ruling Minimum Radius(RMR), 2. Absolute Minimum Radius(AMR), 3. Radius beyond which no superelevation is required (RBNSN).
ExtraWidening: Off tracking, Extrawidening is split up into two parts- (i) Mechanical widening, (ii) Psychological widening.
Transition Curves, Different Types of Transition Curves ⇒ 1. Spiral, 2. Bernoulli’s Lemniscate, 3. Cubic Parabola. Length of Transition Curve⇒ 1. Length of Transition Curve by the Rate of Change of Radial Acceleration, 2. Length of Transition Curve by Rate of Change of Superelevation, 3. Empirical Formula for the Length of Transition Curve Recommended by IRC. Setting Out of Transition Curve
Set Back Distance– Calculation Of Setback Distance: Case 1: When the length of horizontal curve greater than the sight distance (LC>SD)⇒ (a) For Single Lane, (b) For Multi lane. Case 2: When the length of horizontal curve less than the sight distance (LC<SD) ⇒ (a) For Single Lane, (b) For Multi lane.

Design of Vertical Alignment Gradient, Type of Gradients– Ruling Gradient, Limiting Gradient, Exceptional Gradient, Minimum Gradient.
Vertical Curve
Summit Curve, Derivation of Summit Curve⇒ 1. General Equation of Summit Curve, 2. Position of Summit / Highest / Crest Point of Curve From VPC, 3. Apex Equation of Summit Curve, 4. Position pf VPI from VPC, 5. Calculating Ordinates of Summit Curve. Length Of Summit Curve⇒ Case-1: When LS> SD (Sight Distance), Case-2: When LS< SD (Sight Distance).
Valley Curve, Length Of Valley Curve ⇒ Criteria 1: As per Comfort Condition, Criteria 2: As per HSD  Case-1: When LV> HSD, Case-2: When LV< HSD. 

  Traffic Engineering  

Traffic Engineering
1. Traffic Characteristics:  A. Road User Characteristics: Vision  B. Vehicular Characteristics: Dimension, Weight of Loaded Vehicle, Power of Vehicle, Speed of Vehicle. C. Breaking Characteristics: ⇒ Retardation, ⇒ Skid Distance, ⇒ Skid Resistance, ⇒ Breaking Efficiency.

2. Traffic Studies and Analysis  
A. Traffic Volume Study: Traffic Volume (q), PCU (Passenger Car Unit), Measurements of Traffic Volume: Manual Method, Mechanical Method. Presentation Of Traffic Volume Data: i. Annual Average Daily Traffic (AADT), ii. Annual Average Hourly Traffic (AAHT), iii. Annual Average Week Day Traffic (AAWT), iv. Average Daily Traffic (ADT), v. Trend Chart, vi. 30th Highest Hourly Volume, vii. Volume Flow Diagram at Intersection, viii. Variation Chart,, Periodic Volume Count: 1. Hourly Expansion Factor (HEF), 2. Daily Expansion Factor (DEF), 3. Monthly Expansion Factor (MEF). Peak Hour Factor (PHF)
B. Traffic Speed Studies: Types of Speed: a. Spot Speed, b. Average Speed⇒ i. Time Mean Speed, ii. Space Mean Speed, c. Journey Speed, d. Running Speed, Generally, there are two types of speed studies carried out ⇒ 1. Spot Speed Study: Representation Of Spot Speed Data⇒ Speed Distribution Table, Frequency Distribution Curve, Cumulative Speed of Vehicle: 98th percentile speed, 85th percentile speed, 15th Percentile Speed, 50th percentile speed. 2. Speed And Delay Study: Floating Car Method, Derivation Of Floating Car Method.  
C. Traffic Flow Characteristics & Capacity Study: i. Traffic Capacity Studies: Traffic Volume, Traffic Density (K), Jam Density (Kj), Space Headway (S), Time Headway (HT), Traffic Capacity, Basic Capacity, Practical capacity, Calculation of Theoretical Maximum Capacity ⇒ Max Theoretical Capacity from Space Headway, Max Theoretical Capacity from Time Headway. ii. Traffic Flow Characteristics Studies: Macroscopic Characteristics⇒ Green Shield’s Stream Model., Microscopic Characteristics, Delay & Queue Analysis at Signalized Intersection⇒ Delay (D), Queue (Q).
D. Origin and Destination (O & D) Study: Representation of Origin and Destination Data: O&D Table, Desire Lines, Pie Chart.
E. Accident Study: Mathematical Analysis of Accident Studies, Accident Case Study⇒ When A Moving Vehicle Collides With a Parked Vehicle.
F. Parking Study: Parking facilities may be divided into two types  a. Off-Street Parking b. On Street/ Kerb Parking ⇒ i. Parallel Parking, ii. Angle Parking: 30° Angle Parking, 45° Angle Parking, 60° Angle Parking, 90° Angle Parking.  Parking statistics⇒ Parking Accumulation, Parking Volume, Parking load, Average Parking Duration, Parking Turnover, Parking Index.

 3. Traffic Control Devices & Regulation  
A. Intersection
 i. Intersection at Grade: Requirements of Intersection at Grade, Type of Intersection at Grade: a. Unchannelized Intersections, b. Channelized Intersections, c. Rotary Intersection: Design Factors For Rotary Intersection⇒ i. Design Speed, ii. Shape of Rotary Island, iii. Radius of Curve at Entry, iv. Radius of Curve at Exit, v. Radius of Central  Island, vi. Width of Carriageway At Exit & Entry, vii. Width of non-weaving section, viii. Width & Length of Weaving Section, ix. Length of Weaving Section, x. Capacity Of Rotary.
ii. Grade Separated Intersection: A. Trumpet interchange, B. Diamond interchange, C. Full Cloverleaf interchange, D. Partial Cloverleaf interchange, Advantages of Grade Separation, Disadvantages of Grade Separation

B. Traffic Signals
Type of Traffic Signals: a. Traffic Control Signals⇒ i. Fixed-time Signal, ii. Traffic Actuated (automatic) Signal, iii. Manually Operated Signal., b. Pedestrian Signal, c. Special Traffic Signal
Type of Coordination of Traffic Signal System: Simultaneous System, Alternate System, Simple Progressive System, Flexible Progressive System.
Important Terminology of Traffic Signals⇒ 1. Cycle, 2. Cycle Length (C), 3. Interval, 4. Green Time, 5. Red Time, 6. Amber Time, 7. Phase, 8. Lost Time (tL): Startup Lost Time (tSL), Clearance Lost Time (tCL), 9. Effective Green Time (gi), 10. Lane Capacity, Method of Signal Designing, Webster Method. 

C.  Traffic Sign: Classification of Signs⇒ i. Regulatory / Mandatory Signs, ii. Warning/ Cautionary Sings, iii. Informatory Sign.
D. Road Marking: Functions of Road Markings, Types of Road Marking ⇒ a. Pavement Marking: Centre Lines, Lane Line, Edge Lines, No Passing Zone Marking, Turn Markings, Stop Line, Crosswalk Lines,Bus Stops. ,  b. Kerb Marking, c. Object Marking, d. Reflector Unit Marking, Road Delineators

  Pavement Design  

Pavement Design: Introduction, Types of Pavement in Highway Engineering: Flexible Pavement, Rigid Pavement, Semi Rigid Pavement, Composite Pavement, Difference Between Flexible and Rigid Pavement, Functions of Pavement Components: Soil Subgrade, Sub Base and Base Course, Wearing course. 
Design Parameters of  Pavement⇒ Standard Axle Load, Rigidity Factor(RF): Contact Pressure and Tyre Pressure,  Equivalent Single Wheel Load (ESWL for dual wheel Assembly)
No of Repetition, Lane Distribution Factor (L.D.F): Single Carriageway, Dual Carriageway. Vehicle Damage Factor: Equivalent axle load Factor (EALF).
Method of Pavement Design: Empirical Method, Semi Empirical or Semitheoretical Method, Theoretical Methods. Group Index Method, California Bearing Ratio Method (CBR Method), Triaxial Test Method, Design of Rigid Pavement: Modulus of Subgrade Reaction, Radius of Relation Stiffness (l), Equivalent Radius of Relation Section, Factors Affecting Pavement Design  
Analysis of Stress: Load Stress⇒ Nature of there stress are as follows: (A) At Interior/ Edge Region, (B) At Corner  of slab. Temperature Stresses: Warping Stress: At Interior Side, At Edge Side, At Corner Side, Frictional Stress. Worst Combination Of Stress: Critical Cases of Stress Combination.
Design of Joints⇒ Expansion Joint: Dowel Bar At expansion Joint, Contraction Joint: Case.1 Without Dowel Bar, Case.2 With Dowel Bar, Longitudinal Joint: Design of tie bars, Length of tie bars (Lt). Materials Used In Rigid Pavement, Difference Between Dowel Bars and Tie Bars