diff --git a/binaries/data/mods/public/simulation/ai/common-api/map-module.js b/binaries/data/mods/public/simulation/ai/common-api/map-module.js
index 00a255c232..515a927d27 100644
--- a/binaries/data/mods/public/simulation/ai/common-api/map-module.js
+++ b/binaries/data/mods/public/simulation/ai/common-api/map-module.js
@@ -9,7 +9,7 @@ var API3 = function(m)
 m.Map = function Map(sharedScript, type, originalMap, actualCopy)
 {
 	// get the correct dimensions according to the map type
-	var map = (type === "territory" || type === "resource") ? sharedScript.territoryMap : sharedScript.passabilityMap;
+	let map = (type === "territory" || type === "resource") ? sharedScript.territoryMap : sharedScript.passabilityMap;
 	this.width = map.width;
 	this.height = map.height;
 	this.cellSize = map.cellSize;   
@@ -45,7 +45,7 @@ m.Map.prototype.gamePosToMapPos = function(p)
 
 m.Map.prototype.point = function(p)
 {
-	var q = this.gamePosToMapPos(p);
+	let q = this.gamePosToMapPos(p);
 	q[0] = q[0] >= this.width ? this.width-1 : (q[0] < 0 ? 0 : q[0]);
 	q[1] = q[1] >= this.width ? this.width-1 : (q[1] < 0 ? 0 : q[1]);
 	return this.map[q[0] + this.width * q[1]];
@@ -233,7 +233,7 @@ m.Map.prototype.multiplyInfluence = function(cx, cy, maxDist, strength, type)
 
 // doesn't check for overflow.
 m.Map.prototype.setInfluence = function(cx, cy, maxDist, value = 0)
-{	
+{
 	var x0 = Math.max(0, cx - maxDist);
 	var y0 = Math.max(0, cy - maxDist);
 	var x1 = Math.min(this.width, cx + maxDist);
@@ -416,7 +416,7 @@ m.Map.prototype.isObstructedTile = function(kx, ky, radius)
 		return true;
 	for (let dy = 0; dy <= radius; ++dy)
 	{
-		let dxmax = Math.ceil(Math.sqrt(radius*radius - dy*dy));
+		let dxmax = (dy == 0) ? radius : Math.ceil(Math.sqrt(radius*radius - (dy-0.5)*(dy-0.5)));
 		let xp = kx + (ky + dy)*w;
 		let xm = kx + (ky - dy)*w;
 		for (let dx = -dxmax; dx <= dxmax; ++dx)
@@ -473,28 +473,6 @@ m.Map.prototype.findNearestObstructed = function(k, radius)
 	return -1;
 };
 
-// returns the point with the lowest (but still > radius) point in the immediate vicinity
-m.Map.prototype.findLowestNeighbor = function(x,y,radius)
-{
-	var lowestPt = [0,0];
-	var lowestcoeff = undefined;
-	x = Math.floor(x/this.cellSize);
-	y = Math.floor(y/this.cellSize);
-	for (let xx = x-1; xx <= x+1; ++xx)
-	{
-		for (let yy = y-1; yy <= y+1; ++yy)
-		{
-			if (xx < 0 || xx >= this.width || yy < 0 || yy >= this.width)
-				continue;
-			if (lowestcoeff && this.map[xx+yy*this.width] > lowestcoeff)
-				continue;
-			lowestcoeff = this.map[xx+yy*this.width];
-			lowestPt = [(xx+0.5)*4, (yy+0.5)*4];
-		}
-	}
-	return lowestPt;
-};
-
 m.Map.prototype.dumpIm = function(name = "default.png", threshold = this.maxVal)
 {
 	Engine.DumpImage(name, this.map, this.width, this.height, threshold);
diff --git a/binaries/data/mods/public/simulation/ai/common-api/shared.js b/binaries/data/mods/public/simulation/ai/common-api/shared.js
index 793127cb6e..7027c3d345 100644
--- a/binaries/data/mods/public/simulation/ai/common-api/shared.js
+++ b/binaries/data/mods/public/simulation/ai/common-api/shared.js
@@ -147,7 +147,7 @@ m.SharedScript.prototype.init = function(state, deserialization)
 /*
 	var landPassMap = new Uint8Array(this.passabilityMap.data.length);
 	var waterPassMap = new Uint8Array(this.passabilityMap.data.length);
-	var obstructionMaskLand = this.passabilityClasses["default"];
+	var obstructionMaskLand = this.passabilityClasses["default-terrain-only"];
 	var obstructionMaskWater = this.passabilityClasses["ship-small"];
 	for (var i = 0; i < this.passabilityMap.data.length; ++i)
 	{
diff --git a/binaries/data/mods/public/simulation/ai/petra/queueplan-building.js b/binaries/data/mods/public/simulation/ai/petra/queueplan-building.js
index fa3758c015..67f8845201 100644
--- a/binaries/data/mods/public/simulation/ai/petra/queueplan-building.js
+++ b/binaries/data/mods/public/simulation/ai/petra/queueplan-building.js
@@ -32,7 +32,7 @@ m.ConstructionPlan.prototype.canStart = function(gameState)
 	if (this.template.requiredTech() && !gameState.isResearched(this.template.requiredTech()))
 		return false;
 
-	return (gameState.findBuilders(this.type).length != 0);
+	return (gameState.findBuilders(this.type).length > 0);
 };
 
 m.ConstructionPlan.prototype.start = function(gameState)
@@ -89,7 +89,7 @@ m.ConstructionPlan.prototype.start = function(gameState)
 				builders[0].construct(this.type, pos.x+shift*sina, pos.z+shift*cosa, pos.angle, this.metadata);
 		}
 	}
-	else if (pos.x == pos.xx && pos.z == pos.zz)
+	else if (pos.xx === undefined || (pos.x == pos.xx && pos.z == pos.zz))
 		builders[0].construct(this.type, pos.x, pos.z, pos.angle, this.metadata);
 	else // try with the lowest, move towards us unless we're same
 	{
@@ -123,7 +123,7 @@ m.ConstructionPlan.prototype.findGoodPosition = function(gameState)
 		if (newpos && newpos.quality > 0)
 		{
 			let pos = newpos.pos;
-			return { "x": pos[0], "z": pos[1], "angle": 3*Math.PI/4, "xx": pos[0], "zz": pos[1], "base": this.metadata.base };
+			return { "x": pos[0], "z": pos[1], "angle": 3*Math.PI/4, "base": this.metadata.base };
 		}
 	}
 	
@@ -140,7 +140,7 @@ m.ConstructionPlan.prototype.findGoodPosition = function(gameState)
 				var pos = gameState.ai.HQ.findStrategicCCLocation(gameState, template);
 
 			if (pos)
-				return { "x": pos[0], "z": pos[1], "angle": 3*Math.PI/4, "xx": pos[0], "zz": pos[1], "base": 0 };
+				return { "x": pos[0], "z": pos[1], "angle": 3*Math.PI/4, "base": 0 };
 			else
 				return false;
 		}
@@ -149,7 +149,7 @@ m.ConstructionPlan.prototype.findGoodPosition = function(gameState)
 			var pos = gameState.ai.HQ.findDefensiveLocation(gameState, template);
 
 			if (pos)
-				return { "x": pos[0], "z": pos[1], "angle": 3*Math.PI/4, "xx": pos[0], "zz": pos[1], "base": pos[2] };
+				return { "x": pos[0], "z": pos[1], "angle": 3*Math.PI/4, "base": pos[2] };
 			else if (!template.hasClass("Fortress") || gameState.civ() === "mace" || gameState.civ() === "maur" ||
 				gameState.countEntitiesByType(gameState.applyCiv("structures/{civ}_fortress"), true)
 				+ gameState.countEntitiesByType(gameState.applyCiv("structures/{civ}_army_camp"), true) > 0)
@@ -164,7 +164,7 @@ m.ConstructionPlan.prototype.findGoodPosition = function(gameState)
 				if (!this.metadata)
 					this.metadata = {};
 				this.metadata.expectedGain = pos[3];
-				return { "x": pos[0], "z": pos[1], "angle": 3*Math.PI/4, "xx": pos[0], "zz": pos[1], "base": pos[2] };
+				return { "x": pos[0], "z": pos[1], "angle": 3*Math.PI/4, "base": pos[2] };
 			}
 			else if (!pos)
 				return false;
@@ -191,13 +191,13 @@ m.ConstructionPlan.prototype.findGoodPosition = function(gameState)
 		if (this.metadata && this.metadata.base !== undefined)
 		{
 			var base = this.metadata.base;
-			for (var j = 0; j < placement.map.length; ++j)
+			for (let j = 0; j < placement.map.length; ++j)
 				if (gameState.ai.HQ.basesMap.map[j] == base)
 					placement.map[j] = 45;
 		}
 		else
 		{
-			for (var j = 0; j < placement.map.length; ++j)
+			for (let j = 0; j < placement.map.length; ++j)
 				if (gameState.ai.HQ.basesMap.map[j] != 0)
 					placement.map[j] = 45;
 		}
@@ -238,7 +238,7 @@ m.ConstructionPlan.prototype.findGoodPosition = function(gameState)
 
 		if (template.hasClass("Farmstead"))
 		{
-			for (var j = 0; j < placement.map.length; ++j)
+			for (let j = 0; j < placement.map.length; ++j)
 			{
 				var value = placement.map[j] - (gameState.sharedScript.resourceMaps["wood"].map[j])/3;
 				placement.map[j] = value >= 0 ? value : 0;
@@ -256,7 +256,7 @@ m.ConstructionPlan.prototype.findGoodPosition = function(gameState)
 	if (this.metadata && this.metadata.base !== undefined)
 	{
 		var base = this.metadata.base;
-		for (var j = 0; j < placement.map.length; ++j)
+		for (let j = 0; j < placement.map.length; ++j)
 		{
 			if (gameState.ai.HQ.basesMap.map[j] != base)
 				placement.map[j] = 0;
@@ -267,8 +267,8 @@ m.ConstructionPlan.prototype.findGoodPosition = function(gameState)
 
 			if (placement.map[j] > 0)
 			{
-				var x = (j % placement.width + 0.5) * cellSize;
-				var z = (Math.floor(j / placement.width) + 0.5) * cellSize;
+				let x = (j % placement.width + 0.5) * cellSize;
+				let z = (Math.floor(j / placement.width) + 0.5) * cellSize;
 				if (gameState.ai.HQ.isNearInvadingArmy([x, z]))
 					placement.map[j] = 0;
 			}
@@ -276,7 +276,7 @@ m.ConstructionPlan.prototype.findGoodPosition = function(gameState)
 	}
 	else
 	{
-		for (var j = 0; j < placement.map.length; ++j)
+		for (let j = 0; j < placement.map.length; ++j)
 		{
 			if (gameState.ai.HQ.basesMap.map[j] == 0)
 				placement.map[j] = 0;
@@ -290,8 +290,8 @@ m.ConstructionPlan.prototype.findGoodPosition = function(gameState)
 
 			if (placement.map[j] > 0)
 			{
-				var x = (j % placement.width + 0.5) * cellSize;
-				var z = (Math.floor(j / placement.width) + 0.5) * cellSize;
+				let x = (j % placement.width + 0.5) * cellSize;
+				let z = (Math.floor(j / placement.width) + 0.5) * cellSize;
 				if (gameState.ai.HQ.isNearInvadingArmy([x, z]))
 					placement.map[j] = 0;
 			}
@@ -314,7 +314,7 @@ m.ConstructionPlan.prototype.findGoodPosition = function(gameState)
 	else if (template.resourceDropsiteTypes() === undefined && !template.hasClass("House") && !template.hasClass("Field"))
 		radius = Math.ceil((template.obstructionRadius() + 4) / obstructions.cellSize);
 	else
-		radius = Math.ceil(template.obstructionRadius() / obstructions.cellSize) + 1;
+		radius = Math.ceil(template.obstructionRadius() / obstructions.cellSize);
 
 	if (template.hasClass("House") && !alreadyHasHouses)
 	{
@@ -337,34 +337,20 @@ m.ConstructionPlan.prototype.findGoodPosition = function(gameState)
 	var x = ((bestIdx % obstructions.width) + 0.5) * obstructions.cellSize;
 	var z = (Math.floor(bestIdx / obstructions.width) + 0.5) * obstructions.cellSize;
 
-	var xx = x;
-	var zz = z;
 	if (template.hasClass("House") || template.hasClass("Field") || template.resourceDropsiteTypes() !== undefined)
 	{
-		if (obstructions.cellSize != 4)  // new pathFinder branch
+		let secondBest = obstructions.findNearestObstructed(bestIdx, radius);
+		if (secondBest >= 0)
 		{
-			let secondBest = obstructions.findNearestObstructed(bestIdx, radius);
-			if (secondBest >= 0)
-			{
-				x = ((secondBest % obstructions.width) + 0.5) * obstructions.cellSize;
-				z = (Math.floor(secondBest / obstructions.width) + 0.5) * obstructions.cellSize;
-				xx = x;
-				zz = z;
-			}
-		}
-		else
-		{
-			obstructions.expandInfluences();
-			let secondBest = obstructions.findLowestNeighbor(x,z);
-			xx = secondBest[0];
-			zz = secondBest[1];
+			x = ((secondBest % obstructions.width) + 0.5) * obstructions.cellSize;
+			z = (Math.floor(secondBest / obstructions.width) + 0.5) * obstructions.cellSize;
 		}
 	}
 
-	let territorypos = placement.gamePosToMapPos([x,z]);
+	let territorypos = placement.gamePosToMapPos([x, z]);
 	let territoryIndex = territorypos[0] + territorypos[1]*placement.width;
 	// default angle = 3*Math.PI/4;
-	return { "x": x, "z": z, "angle": 3*Math.PI/4, "xx": xx, "zz": zz, "base": gameState.ai.HQ.basesMap.map[territoryIndex] };
+	return { "x": x, "z": z, "angle": 3*Math.PI/4, "base": gameState.ai.HQ.basesMap.map[territoryIndex] };
 };
 
 /**
@@ -501,7 +487,7 @@ m.ConstructionPlan.prototype.findDockPosition = function(gameState)
 		}
 	}
 
-	return { "x": x, "z": z, "angle": bestAngle, "xx": x, "zz": z, "base": baseIndex, "access": bestLand };
+	return { "x": x, "z": z, "angle": bestAngle, "base": baseIndex, "access": bestLand };
 };
 
 // Algorithm taken from the function GetDockAngle in simulation/helpers/Commands.js