- Conveyor one-way cross: A path junction where enemy routes cross without merging, keeping traffic flowing in one direction.
- Core rule: Each lane must stay continuous and navigable so monsters never reverse or stall.
- Tower value: Cross points let one tower cover two or more lanes at once, multiplying effective attack time.
- Best placement: Put your strongest damage towers at the center of the crossing zone.
- Common mistake: Building lanes too close together, leaving no room for towers between them.
What Is a Conveyor One Way Cross in Build a Tower Defense?
Build a Tower Defense lets you design the routes monsters travel instead of defending a fixed road. A conveyor one-way cross is a layout technique where two or more one-directional path lanes intersect in an X or + pattern. Enemies on each lane keep moving in their own direction — the lanes cross physically, but monster traffic never merges or reverses.
This technique matters because crossings concentrate enemy traffic into a small area. Any tower placed at the intersection can attack multiple lanes during a single pass, which effectively raises your damage output without buying extra towers.
A tower at a one-way cross attacks enemies from every lane that passes through its range. One position, multiple targets — this is the same principle behind the Central Coverage layout, where towers near the middle of a route cover several path sections at once.
| Layout Element | What It Does | Priority |
|---|---|---|
| One-way lanes | Keep monster traffic moving in a single direction | Required |
| Cross point | Intersects lanes so towers cover multiple routes | Required |
| Center tower zone | Reserved space at the intersection for towers | High |
| Turn buffer | Extra tiles around the cross for future expansion | Medium |
| Exit lanes | Continuous routes leading toward the castle | Required |
Step-by-Step: Building Your One-Way Cross
Follow this construction sequence to build a valid crossing layout from scratch. Build the lanes first, reserve the tower zone second, and always confirm the route remains continuous before adding complexity.
Reserve the Crossing Zone
Pick a central area of your buildable space and mark it for towers only. Do not lay path tiles here. This zone becomes the high-value defensive position where lanes converge.
Lay the First One-Way Lane
Build a straight or gently winding lane that passes along one side of the reserved zone. Confirm monsters travel it in one direction only, from spawner toward the castle.
Lay the Second Lane Across It
Build a second lane crossing the first at roughly a perpendicular angle. The lanes intersect as tiles, but each route stays continuous and one-directional for its own traffic.
Add Optional Branch Lanes
If space allows, add a third lane to create additional cross points. Keep lanes parallel enough that towers in the center zone can reach several of them.
Place Towers at the Center
Deploy your strongest damage towers in the reserved zone so their range overlaps as many lanes as possible. Add crowd-control or multi-target towers next if available.
Test With a Wave and Refine
Run a wave and watch where enemies take little or no damage. Extend exposed lane sections, shift towers toward better coverage, and retest. Change one element at a time.
Every lane must remain a continuous, navigable route from its spawner to the castle. If a cross breaks the path or traps monsters, the layout fails regardless of how good your tower coverage looks.
Cross Layout Types Compared
Different crossing patterns suit different stages of the game. Compare these four configurations and pick the one that matches your available space and tower options.
| Cross Layout | Difficulty | Best For | Key Trade-off |
|---|---|---|---|
| Simple X cross | Beginner | First crossing, learning the mechanic | Only one intersection, limited coverage |
| Serpentine cross | Intermediate | Rectangular spaces, longer travel distance | Rows can crowd out tower spots |
| Spiral cross | Advanced | Very long routes, layered coverage | Hard to expand after building |
| Final-approach cross | Beginner–Intermediate | Backup defense before the castle | Weakens early coverage if overused |
Simple X Cross
- Two lanes, one intersection
- Fast to build and easy to fix
- Great first project for learning crossings
Serpentine Cross
- Back-and-forth lanes with shared turns
- Multiple cross points in a rectangle
- Best coverage-per-tile for mid game
Spiral Cross
- Outer route spiraling inward
- Longest total travel distance
- Plan the exit before closing inner loops
Final-Approach Cross
- Crossing placed near the castle
- Catches enemies that survive main defenses
- Treat as backup, not your only kill zone
Reserve enough tiles between lanes for at least one tower. Packing lanes together without tower space is the most common reason crossing layouts underperform — the same trap that hurts serpentine builds generally.
Tower Placement at the Cross
Towers are the payoff of a one-way cross. With more than 40 tower options in the game, focus on roles rather than specific names until verified statistics are published.
| Tower Role | Where to Place It | Why It Works at a Cross |
|---|---|---|
| High-coverage damage | Dead center of the intersection | Attacks every lane within range |
| Multi-target damage | Near the busiest crossing | Hits grouped enemies from merged traffic zones |
| Long-range damage | Slightly off-center | Covers outer lanes the center towers miss |
| Single-target damage | Along lanes with durable enemies | Focuses damage on bosses and tanky units |
| Control or slow towers | Just before the cross | Extends time enemies spend in the kill zone |
Do not assume a tower near a corner reaches both sides of a turn. Check its real attack range and targeting behavior before committing — visual proximity alone is misleading.
Common Mistakes and Fixes
Before You Run the Next Wave, Verify:
- Every lane is continuous from spawner to castle
- Lanes have enough spacing for tower placement
- Center towers cover at least two lanes each
- No lane section exists where enemies take zero damage
- Final approach has backup coverage near the castle
| Mistake | Symptom | Fix |
|---|---|---|
| Lanes too close together | No room for towers between lanes | Rebuild with one tower-width of spacing |
| Dead-center tower with poor range | Tower idle while enemies pass | Move it to a lane it can actually reach |
| Cross breaks the path | Monsters stall or route fails | Reconnect tiles and retest continuity |
| All towers at one cross | Enemies survive elsewhere | Distribute coverage along the whole route |
| Overly complex layout | Hard to fix weaknesses | Simplify and change one element at a time |
| Ignoring the final approach | Leaks near the castle | Add turns and towers before the castle entrance |
A longer path only helps when your towers can attack along the added distance. Extra lanes that sit outside every tower's range waste buildable space and weaken your defense.
One-Way Cross FAQ
Q: What does a conveyor one-way cross do in Build a Tower Defense?
It intersects two or more one-directional enemy lanes so that towers placed at the crossing can attack monsters from multiple routes at once, raising effective damage without adding towers.
Q: Can enemy lanes cross without merging in this game?
Yes. The path-building system lets you design routes yourself. Lanes can intersect as tiles while each route stays continuous and one-directional, so traffic on each lane keeps moving toward the castle.
Q: Where should I put my strongest towers in a cross layout?
Place your highest-damage towers in the center of the crossing zone so their range overlaps as many lanes as possible, then support them with long-range towers for outer lanes and control towers just before the cross.
Q: Why do enemies still leak despite a long cross layout?
Length alone does not guarantee kills. Check whether enemies travel sections with no tower coverage, whether lanes are spaced too tightly for towers, and whether your final approach near the castle has backup defenses.