A cart route inside a settlement must carry loaded animal carts from the fields to the stores and workshops on a grade of no more than about 8-10%, with curves of 15-25 m radius for a loaded ox-cart and larger for a heavy wagon, and it should skirt the communal plaza and the housing rather than cross them. Keeping the route off the steepest slope costs length, and on a 20% hillside a road held to 8% must be 2.5 times as long as the direct line up.
Part of Settlement Layout for 150 People
Cart and vehicle routes are the heavy-traffic lines inside a settlement: where loaded carts and animals pass, how steep and tight they may be, and where they must not go.
Heavy Traffic Sets The Grade, The Curve And The Route
The layout guide asks for the industrial zone to lie on a cart-accessible path from both the housing and the fields, and for primary paths 2-3 m wide. The limits that a loaded animal cart imposes come from Road Layout, whose figures are used here:
- Maximum grade for a loaded animal-cart road: about 8-10%. Steeper is for unloaded vehicles; on descent it risks runaways.
- Minimum curve radius: 5-10 m for a footpath or light cart, 15-25 m for a loaded ox-cart road, 30-50 m for a heavy cart or wagon road.
- Crown of 5-8% on an earth road to shed water.
The conflict is between these limits and the layout’s other need: the route must be short and must stay out of the core.
Worked Example: What A Grade Limit Costs On A Hillside
Inputs: ground slope 20% (rise 0.20 per unit run), a required height gain of 10 m, a design grade of 8%.
- Straight up the slope: horizontal distance = 10 ÷ 0.20 = 50 m.
- Along a road held to 8%: horizontal distance = 10 ÷ 0.08 = 125 m.
- Ratio: 125 ÷ 50 = 2.5, so the road is 2.5 times as long as the direct line.
The road-layout article states this same 2.5 as “2.5 m horizontally for every 1 m of height gained”. That reading cannot be right: at 8% a road needs 12.5 m of run per 1 m of height, and a ratio of 2.5 m per 1 m would be a 40% grade. The 2.5 is the ratio of road length to direct length, as worked above. This is flagged in the report.
What You Need
- A contour map and grade survey (Grade Calculation)
- The cart type — one-ox cart, wagon or handcart changes radius and width
- Drainage outlets for the route (Gravel Roads)
Method: Route The Cart Away From People
Step 1: List the flows. Grain and hay from fields to stores; wood and ore to workshops; products and waste out. Note which cross.
Step 2: Join the endpoints without touching the plaza. Run the route along the outside of the housing ring, between agriculture and the storage and industrial zones, which the layout guide puts adjacent.
Step 3: Hold the grade with traversing legs across the slope on hills. Stake at 20 m intervals in rolling terrain (road-layout).
Step 4: Replace sharp corners with curves; tangent length T = R × tan(Δ/2) lays out a curve. For R = 20 m and a 30° deflection: T = 20 × tan 15° = 20 × 0.268 = 5.4 m.
Step 5: Drain. Crown the surface, ditch both sides and cross it with a culvert where a stream or drain meets it.
Common Mistakes
- Straight up the fall line — a gully forms within a season and loaded carts stall.
- Routing carts through the core — dust, noise, injuries to children.
- Gates narrower than the loaded cart and no turning space at the stores.
Safety
Runaway loads and animals near people
A loaded cart that gets away on a steep descent can kill. Keep grades within the limits above, give the route a run-out at the bottom of any descent, and keep it away from play areas, the plaza and the school.
What’s Next
- Learn next: Water Distribution Routes — the other lines that share the corridor
- Combine with: Road Construction Basics — building the surface