← Forays & side projects
Project Co-designFORAYS 180 · 181 · 182

A foray into coupled project choices

Design the
whole promise.

Platforms, signalling and power have to work together. So do the choices that get them built. Explore the railway, the programme and the path between them.

Featured experiment · keep service running through the upgrade

New: can temporary power cover its own overhead? ↗

THE WAY THERE COUNTSOne admissible five-slot path
A temporary bridge makes a rail upgrade deliverable In slot one, upgrade signalling and install the bridge. In slot two, upgrade platforms and signalling. Upgrade the grid in slots three and four. In slot five, complete the platforms and return the bridge. The bridge maintains grid service during cutovers and contributes no final permanent capacity. SLOT 12345 PlatformsSignallingGrid InstallTEMPORARY BRIDGE ACTIVEReturn PERMANENT CAPACITY GROWS. SERVICE CONTINUES.
Useful on the journey. Absent at the destination. A temporary bridge can disappear from the final design and still belong in a least-cost delivery plan.

Co-design keeps the requirements and resource trade-offs of connected systems in the same decision.

ONE INVESTIGATION
SEVERAL WAYS IN

Start with the question you have

Four ways to explore.

Begin with a delivery path, size the power that enables it, compare programme assumptions, or explore a wildlife crossing. Each essay has its own declared model.

01 · Construct a path

Can we keep the whole promise?

Require continued service, shared crews, restricted access or an intermediate milestone. Find feasible action sequences and inspect every step behind the resource trade-offs.

Staged path co-design. Exact finite construction with independently checked witnesses.

Explore delivery paths
02 · Size the enabling work

Can temporary power cover its own overhead?

Battery racks bring cooling allowances. Cooling needs electricity, and conversion loses some as heat. Follow those requirements around the loop until a complete installation emerges.

New · Temporary power co-design. Recorded Python MCDP calculations, with independently checked whole-unit implementations.

Explore the power loop
03 · Compare programmes

Which trade-offs are worth making?

Compare compatible packages, governance assumptions and four supplied staging strategies. See how interface mismatch and an illustrative approvals loop affect the alternatives.

Programme co-design studio. A broader comparison, with an introductory explanation of coupled requirements.

Open the studio
04 · Connect a habitat

What makes a crossing work?

A bridge is one part of the answer. Compose bridge, fencing and monitoring choices; inspect the complete alternatives and the trade-offs they leave between resources.

Wildlife-crossing co-design. A finite component model with explicit interfaces and implementation witnesses.

Explore the crossing

How the parts fit

A choice must have an implementation.

Specify what the system must provide. Keep combinations whose parts satisfy each other’s requirements. Then compare the resources those complete implementations need.

The rail path, temporary-power, programme and wildlife models use this common structure at different levels. Their method notes show the actual interfaces and the limits of the construction.

Read the categorical co-design audit ↗

Ideas you can inspect

Sources, assumptions
and working evidence.

These experiments draw on monotone co-design: represent what connected parts must provide, then retain the resource choices that remain incomparable. The method notes connect the actual constructions to Zardini and Censi, and distinguish model assumptions from checked results.

All are illustrative project models. Their different assumptions belong to each experiment; their results are not interchangeable forecasts.