$fn=64;

// --- Parameters ---
tile_size = 50;         // Length and width of the square tile
road_width = 24;        // Width of the road surface
base_thickness = 2;     // Thickness of the solid base under everything
curb_height = 1.5;      // Height of the sidewalks/curbs above the road
curb_radius = 4;        // Radius of the rounded corners at the intersection

// --- Module ---
module t_intersection() {
    union() {
        // Base plate (solid foundation)
        translate([0, 0, base_thickness / 2])
            cube([tile_size, tile_size, base_thickness], center = true);
        
        // Raised curbs / sidewalks
        translate([0, 0, base_thickness])
            linear_extrude(height = curb_height)
            difference() {
                // Full tile area
                square([tile_size, tile_size], center = true);
                
                // Subtract road area
                // Applying positive then negative offset rounds the concave inner corners
                offset(r = -curb_radius) 
                offset(r = curb_radius) 
                union() {
                    // Main horizontal road (straight across)
                    square([tile_size + 20, road_width], center = true);
                    
                    // Intersecting vertical road (the stem of the T)
                    translate([0, -tile_size / 2])
                        square([road_width, tile_size + 20], center = true);
                }
            }
    }
}

// Render the object
t_intersection();