Civil Engineering (CE) Exam  >  Civil Engineering (CE) Notes  >  Civil Engineering SSC JE (Technical)  >  Cheatsheet: Transportation Engineering

Cheatsheet: Transportation Engineering

Cheatsheet: Transportation Engineering

1. Highway Planning and Alignment

1.1 Highway Classification

Classification TypeCategories
Nagpur Road Plan (1943)National Highways (NH), State Highways (SH), Major District Roads (MDR), Other District Roads (ODR), Village Roads (VR)
By Location & FunctionExpressways, Arterials, Collectors, Local Streets
By Carriage WaySingle, Two-lane, Multi-lane, Dual carriageway

1.2 Road Development Plans

PlanDetails
Nagpur Plan (1943-63)20-year plan, Road density: 16 km/100 sq.km, Star & Grid pattern
Bombay Plan (1961-81)Road density: 32 km/100 sq.km, Focus on rural connectivity
Lucknow Plan (1981-2001)Road density: 82 km/100 sq.km, Fuel-efficient vehicles emphasis

1.3 Highway Alignment

1.3.1 Factors Affecting Alignment

  • Traffic volume and characteristics
  • Topography and gradient requirements
  • Economic considerations and cost
  • Obligatory points (bridges, structures, existing facilities)
  • Environmental and social impacts

1.3.2 Gradient Types

Gradient TypeDefinition
Ruling GradientMaximum gradient used in normal conditions without affecting vehicle speed
Limiting GradientMaximum gradient allowed in exceptional conditions (steeper than ruling)
Exceptional GradientUsed in unavoidable circumstances like mountainous terrain
Minimum GradientFor drainage purposes, minimum 1 in 500 (0.2%)

1.3.3 Grade Compensation

  • Grade compensation on curves = 30 + R / R (%) where R in meters
  • Maximum grade compensation = 75/R
  • No compensation for radius > 600 m

2. Geometric Design of Highways

2.1 Design Speed and Sight Distances

2.1.1 Design Speed Standards (IRC)

Road ClassificationDesign Speed (km/h)
NH/SH - Plain/Rolling100
NH/SH - Hilly80
NH/SH - Steep50
MDR - Plain80
ODR - Plain65

2.1.2 Sight Distance Formulas

TypeFormula
Stopping Sight Distance (SSD)SSD = 0.278Vt + V²/(254f ± 2g), where V=speed (km/h), t=reaction time (2.5s), f=friction, g=gradient (%)
Overtaking Sight Distance (OSD)OSD = Vb(t₁ + 2t₂) where t₁ = 2.5T, T = 0.7V/(9.5S), t₂ = T - t₁/2 + S/2a
Intermediate Sight Distance (ISD)ISD = 2 × SSD
Headlight Sight DistanceSSD for night conditions based on headlight beam angle

2.2 Horizontal Curves

2.2.1 Superelevation

e + f = V²/(127R)

where e=superelevation, f=lateral friction, V=speed (km/h), R=radius (m)

  • Maximum superelevation: 7% (plain/rolling), 10% (hilly/urban with no ice)
  • Minimum radius: Rmin = V²/(127(emax + f))
  • Lateral friction coefficient: 0.15 for speeds 80-100 km/h

2.2.2 Transition Curve

ParameterFormula/Value
Length of TransitionL = V³/(CR) where C=80 (for comfortable rate), or L = 2.7V²/R
Shift (S)S = L²/(24R)
Rate of Superelevation1 in 150 (plain/rolling), 1 in 60 (hilly)
Extra WideningWe = nL²/(2R) + V/(9.5√R), n=number of lanes, L=wheelbase

2.2.3 Setback Distance

  • m = R(1 - cos(θ/2)) where θ = 2860 × SSD / (πR)
  • Required for adequate sight distance on horizontal curves

2.3 Vertical Curves

2.3.1 Summit Curves

ConditionLength Formula
L > SSDL = NS²/(2(h₁½ + h₂½)²), N=|n₁-n₂| (grade difference in %)
L < SSDL = 2SSD - 2(h₁½ + h₂½)²/N
SSD Designh₁=1.2m (driver eye height), h₂=0.15m (object height)
OSD Designh₁=1.2m, h₂=1.2m

2.3.2 Valley Curves

ConditionLength Formula
L > SSDL = NS²/(2(h + S×tan α)), h=0.75m (headlight height), α=1° (beam angle)
L < SSDL = 2SSD - 2(h + S×tan α)/N
Comfort CriteriaL = NV²/395 (based on centrifugal acceleration)

2.4 Cross-Sectional Elements

ElementSpecification
Lane Width3.5m (standard), 3.75m (NH/SH in plain terrain)
Shoulder Width2.5m (paved), 1.5m minimum (unpaved)
CamberConcrete/Bituminous: 2%, Gravel/WBM: 3%, Earth: 4%
Kerb Height15cm (low speed), 10cm (high speed)
Right of Way (ROW)NH: 45m (open), 30m (built-up); SH: 30m (open), 20m (built-up)

3. Highway Materials and Pavement Design

3.1 Aggregates

3.1.1 Aggregate Tests

TestProperty & Limits
Crushing ValueStrength; Max 30% (wearing course), 45% (base course)
Impact ValueToughness; Max 30% (wearing), 40% (base)
Abrasion Value (LAA)Hardness; Max 30% (wearing), 50% (base)
Flakiness IndexShape; Max 30%, measures flat particles
Elongation IndexShape; Max 30%, measures elongated particles
Water AbsorptionPorosity; Max 2% for road aggregates
Soundness TestDurability; Max 12% (Na₂SO₄), 18% (MgSO₄) weight loss
Stripping ValueBitumen adhesion; Min retained coating 95%

3.1.2 Aggregate Gradation

  • Fineness Modulus = (Σ cumulative % retained on standard sieves)/100
  • Dense graded: Well distributed particle sizes for maximum density
  • Open graded: Predominantly single size for drainage
  • Gap graded: Missing one or more intermediate sizes

3.2 Bitumen and Bituminous Materials

3.2.1 Bitumen Tests

TestPurpose & Values
Penetration TestConsistency; 30/40, 60/70, 80/100 grades (1/10 mm at 25°C, 100g, 5s)
Ductility TestTensile property; Min 75 cm at 27°C, 5 cm/min
Softening PointRing & Ball method; 40-60°C for paving grade
Flash & Fire PointSafety; Flash min 220°C, Fire min 240°C
ViscosityFlow resistance; measured at 60°C and 135°C
Specific GravityDensity; 0.97-1.02 for paving bitumen
Solubility in CS₂Purity; Min 99%

3.2.2 Modified Bitumen

  • Cutback bitumen: RC (Rapid Curing), MC (Medium Curing), SC (Slow Curing)
  • Bitumen emulsion: RS (Rapid Setting), MS (Medium Setting), SS (Slow Setting)
  • Polymer modified bitumen (PMB): Enhanced performance with polymers
  • Crumb rubber modified bitumen (CRMB): Uses recycled tire rubber

3.3 Pavement Types and Components

3.3.1 Flexible Pavement Layers

LayerFunction & Materials
Wearing Course (Surface)Resists traffic abrasion; BC, DBM, AC, SDBC (5-7.5 cm)
Binder CourseLoad distribution; DBM, BM (5-10 cm)
Base CourseMajor load distribution; WBM, WMM, CTB (15-30 cm)
Sub-base CourseAdditional support; WBM, WMM, granular material (15-20 cm)
SubgradeFoundation; natural soil, min CBR 2-5%

3.3.2 Rigid Pavement Components

  • Cement concrete slab: M40 grade, 15-30 cm thick
  • Dowel bars: Load transfer at transverse joints (25-40 mm dia, 450-500 mm length)
  • Tie bars: Hold longitudinal joints (10-20 mm dia, 400-700 mm length)
  • Sub-base: DLC (Dry Lean Concrete) or granular material (15 cm min)
  • Joints: Contraction, expansion, construction, warping joints

3.4 Soil Properties for Pavements

3.4.1 CBR (California Bearing Ratio)

CBR = (Test load / Standard load) × 100
  • Standard loads: 1370 kg at 2.5 mm, 2055 kg at 5 mm penetration
  • Subgrade CBR: 2% (poor), 5% (fair), 10% (good)
  • Design CBR = 97.5 percentile value (for flexible pavements)

3.4.2 Soil Stabilization

MethodApplication
Lime StabilizationClayey soils, 2-8% lime content, reduces plasticity
Cement StabilizationSandy/gravelly soils, 3-10% cement, increases strength
Bitumen StabilizationGranular soils, 4-8% bitumen, waterproofing
Chemical StabilizationVarious additives like fly ash, slag for improvement

4. Pavement Design Methods

4.1 Flexible Pavement Design (IRC 37-2018)

4.1.1 Design Parameters

  • Design life: 15-20 years
  • Design traffic: Cumulative standard axles (msa - million standard axles)
  • Standard axle load: 80 kN (single axle, dual wheel)
  • Design CBR: Based on subgrade soil strength
  • Vehicle Damage Factor (VDF): Ratio of damage by vehicle to standard axle

4.1.2 Traffic Calculation

N = 365 × A × D × F × (1+r)n
  • N = cumulative standard axles, A = initial traffic (vehicles/day)
  • D = lane distribution factor, F = VDF, r = growth rate, n = design life
  • Commercial vehicle count for traffic calculation

4.1.3 Pavement Thickness Design

Traffic (msa)Total Thickness (mm) for CBR 2%
< 1230
1-3280
3-10380
10-30480
30-100580
> 100680

4.2 Rigid Pavement Design (IRC 58-2015)

4.2.1 Design Considerations

  • Concrete flexural strength: 4.5 MPa (28 days)
  • Modulus of subgrade reaction (k): 40-130 MPa/m
  • Design life: 30 years
  • Load safety factor (LSF): 1.0-1.2
  • Radius of relative stiffness: l = [Eh³/(12(1-μ²)k)]1/4

4.2.2 Westergaard's Stress Equations

Load PositionCritical Stress
Interior Loadingσᵢ = 0.316P/h² [4 log(l/b) + 1.069]
Edge Loadingσₑ = 0.529P/h² [4 log(l/b) + 0.359]
Corner Loadingσc = 3P/h² [1 - (a√2/l)0.6]

4.2.3 Joint Spacing

  • Contraction joint spacing: 4.5-5.0 m (plain concrete), 10-15 m (reinforced)
  • Expansion joint spacing: 140 m (plain), not required (continuously reinforced)
  • Joint width: 20-25 mm for expansion, 6-10 mm for contraction

4.3 Pavement Failures and Distress

4.3.1 Flexible Pavement Distress

Distress TypeCauses
Alligator CrackingFatigue failure, repeated traffic loading, weak base
RuttingPermanent deformation, inadequate compaction, high temperature
RavelingLoss of aggregates, poor binder quality, aging
BleedingExcess bitumen, low air voids, high temperature
PotholesWater infiltration, weak subgrade, poor drainage

4.3.2 Rigid Pavement Distress

  • Corner breaks: Loss of support, poor load transfer
  • Faulting: Differential settlement at joints, pumping
  • Spalling: Edge deterioration, freeze-thaw cycles
  • Pumping: Ejection of fines through joints, water infiltration
  • Blow-up: Compression failure, inadequate expansion joints

5. Traffic Engineering

5.1 Traffic Flow Characteristics

5.1.1 Fundamental Parameters

ParameterDefinition & Formula
Flow (q)Vehicles passing per unit time; q = N/T (veh/hr)
Speed (v)Rate of movement; Space mean speed = Σdᵢ/Σtᵢ, Time mean speed = Σvᵢ/n
Density (k)Vehicles per unit length; k = N/L (veh/km)
Basic Relationshipq = v × k
Headway (h)Time gap between successive vehicles; h = 1/q
Spacing (s)Distance between successive vehicles; s = 1/k

5.1.2 Greenshields Model

v = vf(1 - k/kj)

where vf = free flow speed, kj = jam density

  • q = vf×k(1 - k/kj) = vf×k - (vf/kj)×k²
  • Maximum flow: qmax = vf×kj/4 at k = kj/2 and v = vf/2
  • Flow at capacity occurs at optimum speed and density

5.2 Traffic Studies

5.2.1 Volume Studies

  • PCU (Passenger Car Unit): Car=1.0, Bus=3.0, Truck=3.0, Two-wheeler=0.5
  • Peak Hour Factor (PHF) = Volume in peak hour / (4 × Volume in peak 15 min)
  • Average Daily Traffic (ADT) = Total volume / Number of days
  • 30th highest hourly volume used for design

5.2.2 Speed Studies

Speed TypeDefinition
Spot SpeedInstantaneous speed at a location; min sample 30 vehicles
Running SpeedLength/running time (excluding stops)
Journey SpeedLength/total travel time (including stops)
85th Percentile SpeedSpeed limit setting, 85% vehicles travel below this
98th Percentile SpeedDesign speed basis

5.2.3 Origin-Destination Studies

  • Methods: Interview method, postcard method, tag method, license plate method
  • Desire line diagram: Visual representation of O-D movements
  • Trip generation, distribution, modal split, traffic assignment

5.3 Traffic Capacity and Level of Service

5.3.1 Highway Capacity

  • Basic capacity: 2000 PCU/hour/lane (ideal conditions)
  • Practical capacity = Basic capacity × lane width factor × lateral clearance factor × terrain factor
  • Service flow rate = Capacity under prevailing conditions

5.3.2 Level of Service (LOS)

LOSV/C Ratio
A (Free flow)< 0.35
B (Stable flow)0.35-0.55
C (Stable, restricted)0.55-0.75
D (Approaching unstable)0.75-0.90
E (Unstable, at capacity)0.90-1.00
F (Forced flow, breakdown)> 1.00

5.4 Intersection Design

5.4.1 At-Grade Intersections

TypeCharacteristics
ChannelizedTraffic islands, defined paths, improved safety
Rotary/RoundaboutOne-way circular flow, suitable for moderate traffic
SignalizedTraffic signals, high volume capacity

5.4.2 Rotary Design

  • Weaving length (Lw): 4W to 8W where W = width of weaving section
  • Entry width: 7-9 m, Exit width: 9-12 m
  • Central island radius: Based on design speed and approach width
  • Capacity: Q = 280W(1 + e/W)/(1 + W/L) where e = entry width, W = weaving width, L = weaving length

5.4.3 Grade-Separated Intersections

  • Types: Diamond, Cloverleaf, Trumpet, Directional
  • Used when traffic volume exceeds at-grade capacity
  • Warrant: ADT > 5000 on major road, > 500 on minor road

5.5 Traffic Signals

5.5.1 Webster's Method

Co = (1.5L + 5)/(1 - Y) seconds
  • L = total lost time per cycle, Y = Σ(yᵢ) = sum of critical flow ratios
  • yᵢ = qᵢ/sᵢ where qᵢ = flow, sᵢ = saturation flow
  • Green time: Gᵢ = (Co - L) × yᵢ/Y

5.5.2 Signal Timing Parameters

ParameterTypical Value
Yellow (Amber) Time3-4 seconds
All Red Time1-2 seconds
Minimum Green7 seconds
Lost Time per Phase4-5 seconds
Cycle Time Range40-120 seconds (optimum 60-90s)

6. Railway and Airport Engineering

6.1 Railway Track Components

6.1.1 Track Elements

ComponentSpecifications
Rail Sections52 kg/m, 60 kg/m (BG); Flat-footed or Bull-headed
Gauge (BG)1676 mm (5'6"); MG: 1000 mm, NG: 762/610 mm
Sleeper SpacingM+5 sleepers per rail length, M = rail length in meters
Ballast Depth250 mm (under sleeper), 150 mm (on sides), crushed stone
Formation Width (BG)6.1 m (single track), 10.82 m (double track)

6.1.2 Track Geometry

Cant (e) = GV²/(127R) mm

G = gauge (m), V = speed (km/h), R = radius (m)

  • Cant deficiency: Max 75 mm (BG)
  • Cant excess: Max 75 mm (stations), 65 mm (other locations)
  • Rate of change of cant: 1 in 360 (max)
  • Transition curve length: L = 0.008CV² for cant C (mm) and speed V (km/h)

6.1.3 Gradients and Curves

  • Ruling gradient: 1 in 100 to 1 in 150 (plains), 1 in 30 to 1 in 50 (hills)
  • Grade compensation on curves: 0.04% per degree of curve (max 0.07%)
  • Minimum curve radius: 175 m (BG), speed-dependent
  • Sharpest curve on Indian Railways: 10° (R = 175 m)

6.2 Airport Planning and Design

6.2.1 Airport Components

  • Airside: Runways, taxiways, aprons, ATC facilities
  • Landside: Terminal buildings, parking, access roads
  • Runway orientation: Along prevailing wind direction, wind rose diagram
  • Wind coverage: Min 95% time, crosswind component max 25 km/h

6.2.2 Runway Design

ParameterSpecification
Runway LengthBased on aircraft type, altitude, temperature; correction factors applied
Runway Width45 m (Code 4E/F), 30 m (Code 3C), based on ICAO codes
Longitudinal GradientMax 1% (first/last quarter), 1.5% (middle half)
Transverse Gradient1.5% (paved), 2% (unpaved) for drainage
Sight DistanceHalf runway length from any point 3 m above runway

6.2.3 Runway Length Corrections

  • Altitude correction: 7% increase per 300 m elevation above MSL
  • Temperature correction: 1% increase per 1°C above standard temperature
  • Gradient correction: 10% increase per 1% effective gradient
  • Standard temperature = 15 - 0.0065h (°C), h = altitude (m)

6.2.4 Taxiway and Apron

  • Taxiway width: 23 m (Code E/F), 15 m (Code C)
  • Taxiway edge safety margin: 1.5-4.5 m depending on code
  • Exit taxiway angle: 30° (high speed), 90° (normal)
  • Apron gradient: 0.5-1% for drainage

6.3 Airport Pavement Design

6.3.1 Flexible Pavement (FAA Method)

  • Design parameters: Aircraft wheel load, tire pressure, CBR of subgrade
  • Design curves provided by FAA for various aircraft types
  • Typical layers: Surface (10-15 cm), Base (15-30 cm), Sub-base (30-60 cm)

6.3.2 Rigid Pavement

  • Concrete strength: Min 40 MPa flexural strength
  • Slab thickness: Based on Westergaard equations, 30-50 cm typical
  • Joint spacing: 7.5 m typical, dowel bars for load transfer

7. Highway Construction and Maintenance

7.1 Bituminous Construction Methods

7.1.1 Surface Treatment

TypeDescription
Prime CoatMC-30/70 on granular base, 0.6-1.0 kg/m², penetration 5-7 mm
Tack CoatRC-1/2 or emulsion, 0.2-0.3 kg/m², bonding between layers
Seal CoatSurface protection, bitumen + aggregates, prevents water infiltration
Surface DressingSingle/double coat, 6-12 mm chips, 0.8-1.5 kg/m² bitumen

7.1.2 Bituminous Mix Types

  • BC (Bituminous Concrete): Dense graded, 5-6% binder, premium quality
  • DBM (Dense Bituminous Macadam): Dense graded, 4.5-5.5% binder, binder course
  • BM (Bituminous Macadam): Open graded, 3.5-4.5% binder
  • SDBC (Semi-Dense Bituminous Concrete): Gap graded, wearing course

7.1.3 Marshall Mix Design

PropertySpecification
Stability (min)900 kg (heavy traffic), 550 kg (medium traffic)
Flow Value2-4 mm
Air Voids3-5%
VMA (min)14-16% depending on aggregate size
VFB65-75%

7.2 Compaction and Quality Control

7.2.1 Compaction Methods

EquipmentSuitable For
Smooth Wheel RollerProof rolling, finishing, 8-10 tonnes
Pneumatic RollerBituminous layers, sealing, kneading action
Vibratory RollerGranular materials, high amplitude-low frequency
Sheep Foot RollerCohesive soils, layer-by-layer compaction
Tandem RollerFinishing bituminous layers

7.2.2 Compaction Control

  • Field density test: Sand replacement, core cutter, nuclear density gauge
  • Compaction requirement: 95-98% of maximum dry density (MDD)
  • Optimum moisture content (OMC) ±2% for effective compaction
  • Layer thickness: Max 150-200 mm loose for granular materials

7.3 Pavement Maintenance

7.3.1 Maintenance Types

TypeScope
Routine MaintenancePatch repairs, crack sealing, pothole filling, minor repairs
Periodic MaintenanceOverlay, surface renewal, seal coat application
Special RepairsMajor rehabilitation, reconstruction, structural strengthening
Preventive MaintenanceFog seal, chip seal, surface treatment before deterioration

7.3.2 Overlay Design

Required overlay thickness = (A/B) × Current thickness
  • A = Future cumulative traffic, B = Allowable traffic for existing pavement
  • Benkelman beam deflection test for structural evaluation
  • Pavement Condition Index (PCI): 0-100 scale for condition rating

7.4 Special Construction

7.4.1 Concrete Roads

  • Concrete mix: M40 grade, slump 25-50 mm
  • Curing: 14-28 days, membrane curing compound permitted
  • Contraction joints: Saw-cut depth = slab thickness/3
  • Texturing: Transverse grooving for skid resistance

7.4.2 Low Volume Roads

  • WBM (Water Bound Macadam): Two-layer construction, 75 mm each
  • WMM (Wet Mix Macadam): Improved WBM with filler and moisture
  • Soil aggregate roads: Natural gravel with binder soil

Highway Engineering - Comprehensive Reference Guide

Complete guide covering planning, geometric design, materials, construction, traffic engineering, and maintenance

The document Cheatsheet: Transportation Engineering is a part of the Civil Engineering (CE) Course Civil Engineering SSC JE (Technical).
All you need of Civil Engineering (CE) at this link: Civil Engineering (CE)

FAQs on Cheatsheet: Transportation Engineering

1. What are the key factors to consider in highway planning and alignment?
Ans. Key factors in highway planning and alignment include the terrain and topography of the area, the intended traffic volume and type, safety considerations, environmental impacts, and connection to existing transportation networks. Furthermore, it is essential to consider the land use planning and socio-economic factors that could influence the highway's effectiveness and integration into the community.
2. What is the significance of geometric design in highway engineering?
Ans. Geometric design is crucial in highway engineering as it involves the layout and dimensions of roadways, ensuring safe and efficient vehicle movement. Important aspects include horizontal and vertical alignment, lane width, sight distance, and superelevation. Proper geometric design enhances road safety, improves traffic flow, and reduces the risk of accidents.
3. How are pavement materials selected for highway construction?
Ans. The selection of pavement materials for highway construction is based on factors such as traffic load, environmental conditions, material availability, and cost. Common materials include asphalt and concrete, which are chosen for their durability, strength, and performance characteristics under different weather conditions. Tests like the Marshall and CBR tests are conducted to evaluate the material properties before selection.
4. What are the main pavement design methods used in transportation engineering?
Ans. The main pavement design methods include the empirical method, mechanistic-empirical method, and the AASHTO (American Association of State Highway and Transportation Officials) design method. These methods consider factors such as traffic loads, subgrade soil properties, and environmental conditions to determine the appropriate thickness and layers of pavement required for durability and performance.
5. What role does traffic engineering play in highway systems?
Ans. Traffic engineering plays a vital role in highway systems by focusing on the safe and efficient movement of people and goods. It involves the study of traffic flow, the design of traffic control devices, and the analysis of traffic patterns. Traffic engineers aim to reduce congestion, improve road safety, and enhance the overall efficiency of the transportation network through effective planning and management strategies.
Explore Courses for Civil Engineering (CE) exam
Get EduRev Notes directly in your Google search
Related Searches
Extra Questions, Previous Year Questions with Solutions, Important questions, MCQs, Objective type Questions, mock tests for examination, shortcuts and tricks, study material, video lectures, Free, practice quizzes, Summary, Sample Paper, Cheatsheet: Transportation Engineering, Semester Notes, Exam, Cheatsheet: Transportation Engineering, Cheatsheet: Transportation Engineering, past year papers, Viva Questions, ppt, pdf ;