Roads, gates and access

A layout is only buildable if a service vehicle — and in the worst case a fire crew — can reach every piece of equipment. The solver treats access as a first-class constraint: it lays the road network before packing equipment, and it verifies reach on every candidate layout before showing it to you.

The perimeter ring (default)

With the default road topology, an access road loops just inside the boundary setback. Equipment fills the area inside the ring. The gate connects through the fence onto the ring, so the whole network is drivable from the entrance.

On a slanted or tapered parcel, the packed field is centered within the ring: rather than leave the equipment hugging one road with a wide empty strip against the opposite one, the solver slides the whole field to equalize the clearance to the two facing roads on each axis. Capacity is unchanged — the field moves as one rigid block, it is never re-packed.

Interior roads appear only where needed: when a site is large enough that equipment in the middle would sit too far from any road, the solver cuts the area into zones with a road between them. The threshold is the vehicle reach setting — a zone flanked by roads may be up to twice the reach across, since a vehicle can serve it from either side. Small sites get no interior roads at all: the ring plus the equipment's own service aisles are the access paths, and cutting a road through a small site would only cost capacity.

Road width is configurable (3 m default). The effective width is never below the drivable-lane minimum of your access settings, so a reserved road is always one a real vehicle can use.

Drive-through

Drive-through replaces the perimeter ring with a single spine road between two gates — an entry and an exit: straight when the gates align, bent to follow them otherwise. The spine always drives straight in from each gate before it turns, so the entrance is never a hard turn onto the fence line — even when a gate sits close to a corner. Extra road sections appear only where the vehicle-reach requirement genuinely demands them; everything else is served from the spine. Both gates move from the Gate sliders, and the gate opening matches the road width. It suits sites where traffic should pass through rather than loop — a delivery route during construction, or an AHJ that requires two points of egress.

No road

The Roads picker also offers No road: no ring, no interior roads. Zones are separated by the fire-safety distance instead of fire roads, and the service aisles between equipment rows become the access paths. On small and narrow parcels this recovers substantial capacity — a 3 m road band along each edge of a shallow site can consume a third of its usable depth.

No road does not mean no access. The solver still:

• reserves a clear apron inside the gate — one drivable width deep — so the entrance never opens straight into equipment, and keeps the E-house away from it;
• verifies that the aisle network actually reaches every unit from the gate, at the drivable width your access settings require.

Whether aisles-as-access is acceptable is a project-level decision — it suits fenced compounds where maintenance access is by light vehicle, and it will not suit sites where the authority requires a dedicated apparatus road. The tool shows you the capacity consequence of each choice; the requirement itself comes from your project.

Small parcels: roads omitted automatically

A perimeter ring takes a road width of buildable depth off all four sides. On a parcel too small for that ring, requiring it would leave nothing to place — so rather than report the site as unbuildable, the solver retries once with the internal roads removed and shows the note "Roads omitted — site too small for an internal road." The equipment still sits behind your configured boundary setback — nothing is pushed onto the fence — and the same aisle-reach checks apply. Only when a parcel is too small to fit any equipment even with roads omitted does the tool ask you to draw a larger area.

Vehicle reach

The access settings in Site details define what counts as reachable:

• Drivable width — the minimum clear width for a lane to count as a road.
• Reach — the maximum distance from any equipment to a drivable, gate-connected lane.

Defaults suit common practice, and both are tunable to your authority's figures. The solver uses reach twice: forward, to decide where interior roads are needed, and backward, to verify every candidate — a layout with unreachable equipment is discarded before you ever see it.

The gate

The Gate slider moves the vehicle gate anywhere on the fence; the fence opens at the gate and the entrance connects to the internal network — the ring road, or the gate apron when no roads are selected. Gates near a boundary corner slide along the fence just enough to fit the opening on one straight segment. The gate position also feeds the access verification: reach is always measured from the gate, so moving it can change which layouts are valid on a tight site.