The Grid vs. the Organic Street#
SLOP2418 — Urban Design Studio
Week 2 · Idris Fenn · 1 March 2027
direct readout · derived measure · worked hypothetical
One question, three answers#
The question: how far apart should two parallel streets be?
- Hippodamus, at Miletus: regular, equal, and the same everywhere.
- The medieval street: whatever the ground, the boundary and the traffic of the day produced, adjusted incrementally.
- Stein and Wright, at Radburn: far enough apart that the interior can be given over to people on foot.
Every one of those three is a defensible answer, and each one costs something different.
The grid was an argument about government#
- Hippodamus laid out Miletus and Piraeus on an orthogonal plan in the fifth century BCE; Aristotle discusses his scheme in Politics, Book II.
- The grid’s first virtue was equal division: identical plots, allocable without dispute, describable without a map.
- Its second was legibility to an administrator who had never been there.
- Traffic was not the argument. Traffic became the argument two and a half thousand years later, and the shape did not change.
Jacobs, on short blocks#
Most blocks must be short; that is, streets and opportunities to turn corners must be frequent.
— Jane Jacobs, The Death and Life of Great American Cities (1961)
Her argument is about who walks past whose front door. Ours will be about how many routes exist. They are the same measurement.
Radburn: the superblock#
Radburn gives the centre to people on foot and funnels every vehicle trip.
A city is not a tree#
A tree has one route. A semi-lattice preserves alternatives.
Configuration predicts movement#
- Hillier and Hanson’s space syntax measures a network’s configuration — how connected each link is to every other — and finds that configuration alone predicts a large share of observed movement.
- The implication for this studio: a layout can be evaluated before anything is zoned into it.
- The test: place the network, place nothing else, and count independent routes between two named corners on paper. Redundancy is already uneven before anything is zoned.
- An empty network has no local origins, so it has no honest traffic to read — there is no unzoned volume overlay. Path-count is the only reading an unzoned layout can give you.
The three patterns at the same scale#
Same ground, three network assumptions.
What the road tool actually gives you#
- Straight, curved and grid modes, with snapping increments that make a regular layout faster to draw than an irregular one.
- Road types with different widths, capacities and upkeep costs per unit length — small road through to arterial.
- Elevation and gradient limits, which the terrace tolerates and Verrall Ridge does not.
- Zoning cells attach to road frontage to a limited depth, so frontage is the resource the road network is producing.
Lane-kilometres per dwelling#
All three layouts on the same 480 m by 480 m square of Halstead Reach, all zoned low-density residential to the same depth.
| Layout | Road length in the square | Dwellings reachable | Road metres per dwelling | Monthly upkeep, relative |
|---|---|---|---|---|
| A — fine grid, 80 m | ~5.8 km | high | lowest per dwelling on frontage, highest per hectare | 1.00 |
| B — organic, contour-led | ~3.4 km | moderate | moderate | 0.59 |
| C — superblock, 240 m | ~2.4 km | moderate, with a dead core | high, because the core cannot be zoned | 0.41 |
The upkeep column is charged every month. The layout is drawn once.
Close one link#
The redundancy test, stated as a procedure students run on Monday:
- Build the layout. Zone nothing.
- Pick two named corners and count independent routes between them on paper.
- Remove one link on paper — the busiest topological one.
- Count independent routes between the same two corners again.
| Layout | Routes before | Routes after removal |
|---|---|---|
| A — fine grid | Three or four parallel routes | Redistributes; still two or three remain |
| B — organic | Two routes | One route remains |
| C — superblock | One route | Zero; the two corners are no longer connected |
The tradeoff of the week#
Route redundancy is bought with road length. Road length is charged monthly. The fine grid buys mobility performance and pays for it in fiscal performance.
- The grid gives four routes and 5.8 km of upkeep per square.
- The superblock gives one route and 2.4 km of upkeep per square.
- Neither number improves later. Choose the dimension this week and live with it until Week 12.
Where livability sits in this#
- The grid’s cost is not only fiscal. A grid with no hierarchy invites through-traffic onto residential frontage, and noise pollution lands on the dwellings that face it.
- Read it in the noise pollution overlay, then read the land value overlay over the same blocks and watch the two figures move against each other.
- Radburn’s answer was to separate the two networks entirely. Jacobs’s answer was that the street traffic is the point.
- Both answers are on the table in this studio. Week 9 is where the public realm consequences of this week’s choice are finally marked.
Monday’s studio#
- Lay out the first residential quarter of your settlement area at one chosen block dimension, stated in metres in your notes.
- Zone nothing yet. Bring the unzoned path-count table: independent routes between two named corners and the frontage metres the zoning tool can reach.
- Run the close-one-link test and bring the before-and-after route counts. Bring the numbers, not a description of the numbers.
- Bring the road upkeep figure from the economy panel, and the road metres per dwelling you have derived from it.
- Save as
<student ID>-w02, off-machine copy as usual. Monday studio, 13:00–16:00; upload the record by 21:00.