Phase IV · Research Methodology · Week 8
Transportation Engineering Methodology
Plan traffic, geometric, pavement or airport work with the right studies and design controls.
Preliminary work only. Calculations, models and estimates produced here are student coursework for proposal development. They are not sealed engineering documents and do not replace professional engineering judgment.
Transportation Engineering Methodology
Plan traffic, geometric, pavement or airport work with the right studies and design controls.
Learn
Learning objectives
- Select the correct traffic study
- Apply geometric design controls
- Plan a pavement or airport design procedure
Engineering guidance
A traffic study without a stated count period, date and method cannot be defended.
FE Civil connection
Transportation Engineering
Handbook §9 — Geometric design and traffic (placeholder)
- What stopping sight distance is required at a design speed?
- How is peak hour factor computed?
- What ESAL count drives a pavement thickness?
Technical methodology planner
Plan Chapter 3 against the exact equations, standards, data sources and design checks you will execute in Capstone II.
Write
Transportation methodology workflow
0/21 completeLevel of service reference (HCM volume-to-capacity screening)
| LOS | v/c ratio | Description |
|---|---|---|
| A | ≤ 0.60 | Free flow, minimal delay |
| B | 0.61 – 0.70 | Reasonably free flow |
| C | 0.71 – 0.80 | Stable flow, noticeable delay |
| D | 0.81 – 0.90 | Approaching unstable flow |
| E | 0.91 – 1.00 | At or near capacity |
| F | > 1.00 | Breakdown / oversaturated |
Design speed and stopping sight distance (AASHTO Green Book)
Reaction distance = 1.47Vt = 1.47 × 45 × 2.5 = 165.4 ft
Braking distance = V²/[30(f±G)] = 45²/[30(0.35+0.00)] = 192.9 ft
SSD = reaction + braking = 358.2 ft
Horizontal curve geometry and superelevation
L = RΔ(rad) = 1000 × 0.5236 = 523.6 ft
T = R·tan(Δ/2) = 267.9 ft
E = R[1/cos(Δ/2) − 1] = 35.3 ft
fside ≈ 0.16 − 0.0015V = 0.092
Rmin = V²/[15(e+f)] = 885 ft (provided R adequate)
Vertical curve length (crest/sag, sight-distance controlled)
Curve type
A = |g1 − g2| = 5.00%
S (SSD) = 358.2 ft
L = 284.8 ft (crest curve, sight-distance controlled per AASHTO)
Level of service screening and peak hour factor
v/c = V/C = 1600/1900 = 0.84 → LOS D
PHF = V/(4 × V15) = 1600/(4×450) = 0.89
Pavement thickness screening (AASHTO structural number)
SN = a1D1 + a2D2m2 + a3D3m3
= 1.76 + 1.12 + 0.66 = 3.54
Preliminary design summary
| Design item | Value | FE Civil link |
|---|---|---|
| Stopping sight distance | 358.2 ft | Transportation — sight distance |
| Horizontal curve length | 523.6 ft | Transportation — geometric design |
| Vertical curve length | 284.8 ft | Transportation — geometric design |
| Level of service | D (v/c = 0.84) | Transportation — traffic analysis |
| Pavement structural number | SN = 3.54 | Transportation — pavement design |
Reflection
Do your sight-distance, curve and LOS results reference the correct AASHTO/HCM criteria and is the provided geometry adequate against the computed minimums?
Learning objectives
- Select the correct traffic study
- Apply geometric design controls
- Plan a pavement or airport design procedure
Engineering guidance
A traffic study without a stated count period, date and method cannot be defended.
FE Civil connection
Transportation Engineering
Handbook §9 — Geometric design and traffic (placeholder)
- What stopping sight distance is required at a design speed?
- How is peak hour factor computed?
- What ESAL count drives a pavement thickness?
Technical methodology planner
Plan Chapter 3 against the exact equations, standards, data sources and design checks you will execute in Capstone II.