A planned town from the air — plots, streets and blocks decided before anyone built.Partizanske4 · 19 December 2006 (original upl · The original uploader was MarianZubak at English Wikipedia. · CC BY 2.5 · Commons ↗
A settlement that grows without a layout is not neutral about its future — it is choosing, in advance, that every later improvement will be expensive. Streets too narrow for a cart cannot be widened once they are lined with buildings. Plots with no rear access make waste removal a walk through the house. Ground with no fall, or with waste running downhill into the water supply, produces the disease pattern that city water and sewerage later spends enormous sums to undo. The single decision that matters most is the one made first and revisited never: clean water in, foul water out, and the two never crossing.Separating waste from water is the tier-0 version of the same rule; this is where it becomes geometry.
The shape of it
Read the fall of the ground before drawing anything. Water supply upstream and uphill, waste downstream and downhill, and no route by which one reaches the other. Everything else in this step is negotiable; this is not.
Set the street width for the widest load you expect, then add margin. A cart needs about 3 m to pass; two carts and a person need about 6 m. Retrofitting width means demolition, which means it never happens.
Give every plot two accesses — a front for people and a rear for waste, fuel and animals. Plots with one access route put the midden and the front door on the same path.
Fix a plot module and repeat it. Uniform frontage makes boundaries checkable, division predictable and disputes rare. It does not require uniform buildings.
Leave the fire gaps in from the start. Continuous building along a street is a single fire. Every historical building code was written the week after a city burned; write yours before.
Reserve the corridors you cannot yet use — for a future drain, a wider road, a mill leat. Reserved land is nearly free; reclaimed land is not.
Put the noisome trades downwind and downstream, and record that decision as a rule rather than a preference, or the first tannery to arrive settles it for you.
A block, in planFig 1
Earth / subsoilGravel / aggregateWater
The module repeats: 10 m of frontage by 30 m deep, a 6 m street in front and a 3 m lane behind, so waste, fuel and animals never pass the front door. The row is broken for fire, and every plot is numbered before anyone builds.
A main street, in sectionFig 2
Earth / subsoilMasonry / brickWater
6 m between building lines passes two carts. The surface is crowned so rain runs to side drains on both sides, and the ground under the middle is kept free for the sewer that comes later.
Doing it, step by step
The summary above says what has to happen. This says how, with the numbers that decide whether it works.
1 · Map the fall of the ground and fix the water and waste zones
Water supply upstream and uphill, waste downstream and downhill, and no route by which one reaches the other. Everything else here is negotiable; this is not.
Survey the site with a water level — see irrigation — and draw contour lines on the plan. Mark the water source and its protection zone, the direction water flows over the ground in heavy rain, and the downhill zone where latrines, middens and drains may go — at least 30 m from and downhill of any water source. See sanitation.
✓ Check: The plan shows contours, the water source and its protection zone, and a waste zone at least 30 m downhill of every water source.
2 · Size the streets for the widest load, plus margin
Retrofitting width means demolition, which means it never happens. Planning figures:
A cart needs about 3 m to pass.
Two carts and a person need about 6 m — the minimum for main streets.
Rear service lanes at least 3 m, for waste, fuel and animals.
Peg the building line on both sides of every street before any building goes up, and treat the line as a boundary.
✓ Check: Main streets are pegged at 6 m or more between building lines, and service lanes at 3 m or more, before any building starts.
3 · Fix a plot module with two accesses, and repeat it
Choose one plot size and repeat it — for example, 10 m of frontage by 30 m deep. Uniform frontage makes boundaries checkable, division predictable and disputes rare. It does not require uniform buildings.
Every plot has two accesses: a front onto the street for people, and a rear onto the service lane for waste, fuel and animals. Plots with one access put the midden and the front door on the same path. Number every plot and set its corner monuments — see boundary and tenure.
✓ Check: Every plot on the plan has a number, the standard module, a street frontage and a rear lane access.
4 · Drain the streets away from the water
Give streets a steady fall — around 1 in 100 to 1 in 200 — toward side drains, and lead the drains downhill into the waste zone, never toward or across a water source or supply channel.
Where a drain must cross a water line, the water line goes over the drain, with a solid barrier between them. Line drains in stone or brick where they carry waste, and keep them open and clear so blockages are seen.
✓ Check: After heavy rain, water runs off every street into side drains and away from the water source, with no pooling and no drain crossing above a water line.
5 · Build in fire breaks from the start
Continuous building along a street is a single fire. Every historical building code was written the week after a city burned; write yours before.
Break every row with a gap — several metres, or the width of a street — at regular intervals, or with a masonry party wall that rises above the roof line.
Put a well or cistern within about 100 m of every building, reserved for fire.
✓ Check: No row runs further than the chosen interval without a fire gap or masonry party wall, and every building is within about 100 m of a fire water point.
6 · Reserve the corridors you cannot use yet
Reserved land is nearly free; reclaimed land is not. Mark on the plan and on the ground, and forbid building on:
A future sewer or drain line along each street.
A wider road where traffic will grow.
A mill leat or water main route.
Space for a market, a school and public buildings.
Write the reservations into the property record so they bind every future holder.
✓ Check: Reserved corridors are marked on the plan, pegged on the ground, and written into the property record as unbuildable.
7 · Zone the noisome trades downwind and downstream, as a rule
Tanneries, slaughter yards, smelters, lime kilns and dye works go downwind of the prevailing wind and downstream of every water intake, in a zone of their own, at a stated distance from dwellings — a planning figure of at least 100 m — with its own drainage.
Record it as a rule in the published code, not as a preference, or the first tannery to arrive settles it for you.
✓ Check: The code names the noisome trades and their zone, and every such trade in the settlement sits inside it.
8 · Trace water in and foul water out, on the ground
The test of the whole layout: walk the path of clean water from source to tap or well, and the path of foul water from every latrine and drain to its outfall, and show that they do not meet or cross at any point.
Do this every year, and every time a new building, drain or water line is added. The first new connection that breaks it is the one that brings the outbreak.
✓ Check: This year's walk traced water in and foul water out along their whole lengths, and found no point where they meet or cross.
Build it
Dimensioned drawings, bills of materials and construction procedures for the things this step asks for.
What the record shows was done at this step, what to do instead at this tier, and the evidence. All of them: the better path.
Do not repeat
Streets only as wide as today's traffic
What was done
Most cities laid streets for foot and cart traffic, rebuilt on the same lines after fires, and then spent the 19th and 20th centuries buying back width for sewers, trams and engines.
Do instead
Survey a grid with the widths reserved from the start, and cut the corners of blocks back so vehicles can turn and see.
Evidence
After the Great Fire of 1666, London set aside the new street plans of Wren and Evelyn and rebuilt on the medieval plots. Ildefons Cerdà's 1859 plan for Barcelona's Eixample, drawn decades before motor vehicles, set 20 m streets, blocks about 113 m square and chamfered corners; the grid still carries modern traffic, buses and cycle lanes.
Needs nothing that is not already in hand.
How this fails
Waste routed across or above the water supply, which is the highest-mortality mistake available to a settlement.
Streets sized for people, then needed for carts.
Single-access plots, which put waste on the same route as food.
Continuous frontage with no fire break.
No reserved corridors, so every later utility is cut through somebody's property at ten times the cost.
How you know it worked
VerificationYou can trace, on the ground, the path of clean water in and foul water out, and demonstrate that they do not meet or cross at any point.