STREET module documentation

General Attachment Lab

General Attachment Lab is a browser-based research and teaching module for access-based network growth. It lets users simulate preferential attachment under capacity constraints, spatial cost deterrence, mesh framing, planarity handling, and accessibility-weighted growth, while preserving the true simulated coordinates of the evolving network.

Run app Quick start Packaging notes

Quick Start

Open the app with Run app.
Choose a preset such as BA benchmark or Access-based model.
Click Run once to generate a full network, or Step arrival to inspect the growth process incrementally.
Use the network view, metrics, and charts to compare morphology, degree distribution, clustering, and accessibility.
Switch to Comparison or Batch when you want side-by-side scenarios or replicated summaries.

Direct-open note.

This module is packaged to work from file:// using web/index.html. It loads its standalone JavaScript runtime from web/main.js.

At a glance

What it shows

Growth of a spatial network under degree preference, capacity limits, spatial cost, multi-link entry, planarity rules, and accessibility semantics.

What you can inspect

True-coordinate network geometry, tail diagnostics, clustering, saturation, connectedness, and transport accessibility fields.

What you can export

Graph views, tables, scenario snapshots, and browser-side batch summaries for paper figures or classroom exercises.

How To Use The App

Top-level tabs

Simulation: main interactive mode.
Comparison: compare the current run against saved or copied scenarios.
Batch: run replications and export summaries.
Paper mode: cleaner presentation mode for figure production.

Core controls

Run once: run from the current parameter set to termination.
Step arrival: advance by one arriving node.
Play / Pause: animate repeated arrival steps using the current delay.
Reset: rebuild the simulation from the current parameters and seed.

The app uses a left-hand parameter column, a center network-and-charts column, and a right-hand metrics and accessibility column.

Example Uses

Baseline comparison: compare BA benchmark, capacity-only, spatial-only, and Access-based model outcomes.
Planarity exercise: switch between none, reject_crossings, and split_crossings to see how planar constraints alter growth.
Accessibility experiment: compare network, seed-only, and opportunity-based access semantics within the same split-capable regime.
Batch replication: run repeated browser-side experiments to summarize mean edge length, clustering, tail shape, and saturation.

Things To Notice

The default network view preserves true simulated coordinates rather than forcing a layout algorithm.
Attachment weights shown after a step refer to the first sequential target choice of the most recent arrival.
split_crossings can create additional junction nodes beyond the exogenously arriving nodes.
Some transport accessibility calculations are intentionally limited at larger browser sizes for performance.
The standalone page uses CDN copies of Cytoscape.js and D3, so the first load normally requires internet access.

Sidebar Parameters

Simulation scope

N: final number of exogenously arriving nodes.
kappa: number of links each arriving node attempts to form.
RNG seed: deterministic seed for reproducible runs.
Animation ms: delay between arrivals when using Play.
Replications: active in Batch mode.

Network initialization

Mesh mode and mesh angle settings control lattice framing.
m0, K, seed graph, and capacity mode control the starting network.
Heterogeneous capacity modes expose additional parameter controls.

Arrival and connectivity

Arrival modes control where new nodes appear before target choice.
Arrival preferences can rank candidate sites by accessibility.
alpha, beta, phi, and lambda control the attachment kernel.
Selection rules and access semantics define how targets are weighted.
Planarity mode, mesh adjacency, and related topology controls determine feasible targets.

Reading The Output

Network view

Nodes remain at their simulated coordinates in the unit square.
Split nodes and split links appear when split_crossings is active.
Optional overlays show lattice framing, coordinates, and scale cues.
Attachment-weight labels refer to the first sequential target choice of the most recent arrival.

Metrics and accessibility

Right-hand panels report degree inequality, saturation, connectedness, clustering, edge lengths, and split-node diagnostics.
The transport accessibility panel reports gravity and cumulative accessibility over realized network lengths.
These outputs are most informative when one mechanism changes at a time.

Packaging Notes

This release is designed to travel as a self-contained folder. Keep documentation.html, index.html, and main.js together in the same directory.

The standalone page uses CDN-hosted copies of Cytoscape.js and D3, so first load normally requires an internet connection.

References

Levinson, D., and Yerra, B. (2006). Self-Organization of Surface Transportation Networks. Transportation Science, 40(2), 179-188.
Liao, C.-F., Liu, H. X., and Levinson, D. M. (2009). Simulating Transportation for Realistic Engineering Education and Training: Engaging Undergraduate Students in Transportation Studies. Transportation Research Record, 2109, 12-21.
The current module extends the baseline generalized model into planarity- and accessibility-aware transport-growth experiments documented in this repository.