# Example: Bridge Engineering

**Status:** Draft
**Phase:** The Bedrock Phase

## What This Example Demonstrates

Engineering context preservation (OE-0003), the context record structure, and verification.

## The Observation

A bridge designed without a preserved context record — one that records only the final design but not the reasoning, alternatives, constraints, and verification — creates risk for future engineers who must maintain, modify, or load-rate the bridge.

## Context Record Applied

A well-preserved bridge engineering context record would contain:

| Field | Example Content |
|---|---|
| **Decision** | Use a truss design with a 40m span |
| **Observation** | Site survey showed 40m crossing required; bedrock at 12m depth |
| **Alternatives** | Cable-stayed (rejected: higher maintenance cost), arch (rejected: insufficient abutment capacity) |
| **Constraints** | Maximum load 40 tonnes; environmental: tidal zone; economic: prefabrication required |
| **Reasoning** | Truss allows prefabrication, meets load requirements, and can be erected in tidal window |
| **Verification** | Load testing to 1.5x design load; finite element analysis corroborated by physical test |
| **Lineage** | Builds on standard truss design from [prior project reference] |
| **Assumptions** | Steel grade S355 available; corrosion protection maintains for 50-year design life |

## Self-Fading Assessment

This example transports the reader from the abstract context record structure (OE-0003) to a concrete instance. Once the reader understands how each field maps to a real engineering decision, the example has served its purpose.