diff --git a/src/faction_camp.cpp b/src/faction_camp.cpp
index 5c0dddfe399eb..2b4d3bb814f6c 100644
--- a/src/faction_camp.cpp
+++ b/src/faction_camp.cpp
@@ -555,7 +555,8 @@ void talk_function::start_camp( npc &p )
     }
     const recipe &making = camp_type.obj();
     if( !run_mapgen_update_func( making.get_blueprint(), omt_pos ) ) {
-        popup( _( "%s failed to start the %s basecamp." ), p.disp_name(), making.get_blueprint() );
+        popup( _( "%s failed to start the %s basecamp, perhaps there is a vehicle in the way." ),
+               p.disp_name(), making.get_blueprint() );
         return;
     }
     get_basecamp( p, camp_type.str() );
@@ -2383,7 +2384,8 @@ bool basecamp::upgrade_return( const point &dir, const std::string &miss,
         return false;
     }
     if( !run_mapgen_update_func( making.get_blueprint(), upos ) ) {
-        popup( _( "%s failed to build the %s upgrade." ), comp->disp_name(),
+        popup( _( "%s failed to build the %s upgrade, perhaps there is a vehicle in the way." ),
+               comp->disp_name(),
                making.get_blueprint() );
         return false;
     }
@@ -2720,7 +2722,8 @@ bool basecamp::survey_return()
                                      _( "Select an expansion:" ) );
 
     if( !run_mapgen_update_func( expansion_type.str(), where ) ) {
-        popup( _( "%s failed to add the %s expansion" ), comp->disp_name(),
+        popup( _( "%s failed to add the %s expansion, perhaps there is a vehicle in the way." ),
+               comp->disp_name(),
                expansion_type->blueprint_name() );
         return false;
     }
diff --git a/src/mapgen.cpp b/src/mapgen.cpp
index fc4d6580e5e5e..936b58b8d34fe 100644
--- a/src/mapgen.cpp
+++ b/src/mapgen.cpp
@@ -725,6 +725,9 @@ class jmapgen_alternativly : public jmapgen_piece
                 chosen->get().apply( dat, x, y );
             }
         }
+        bool has_vehicle_collision( mapgendata &dat, int x, int y ) const override {
+            return dat.m.veh_at( tripoint( x, y, dat.zlevel() ) ).has_value();
+        }
 };
 
 /**
@@ -1739,6 +1742,30 @@ class jmapgen_nested : public jmapgen_piece
 
             ptr->nest( dat, point( x.get(), y.get() ) );
         }
+        bool has_vehicle_collision( mapgendata &dat, int x, int y ) const override {
+            const weighted_int_list<std::string> &selected_entries = neighbors.test(
+                        dat ) ? entries : else_entries;
+            if( selected_entries.empty() ) {
+                return false;
+            }
+
+            for( auto &entry : selected_entries ) {
+                if( entry.obj == "null" ) {
+                    continue;
+                }
+                const auto iter = nested_mapgen.find( entry.obj );
+                if( iter == nested_mapgen.end() ) {
+                    return false;
+                }
+                for( auto &nest : iter->second ) {
+                    if( nest->has_vehicle_collision( dat, {x, y} ) ) {
+                        return true;
+                    }
+                }
+            }
+
+            return false;
+        }
 };
 
 jmapgen_objects::jmapgen_objects( const point &offset, const point &mapsize )
@@ -2552,6 +2579,31 @@ void mapgen_function_json_base::formatted_set_incredibly_simple( map &m, const p
     }
 }
 
+bool mapgen_function_json_base::has_vehicle_collision( mapgendata &dat, const point &offset ) const
+{
+    if( do_format ) {
+        for( int y = 0; y < mapgensize.y; y++ ) {
+            for( int x = 0; x < mapgensize.x; x++ ) {
+                const point p( x, y );
+                const ter_furn_id &tdata = format[calc_index( p )];
+                const point map_pos = p + offset;
+                if( ( tdata.furn != f_null || tdata.ter != t_null ) &&
+                    dat.m.veh_at( tripoint( map_pos.x, map_pos.y, dat.zlevel() ) ).has_value() ) {
+                    return true;
+                }
+            }
+        }
+    }
+
+    for( auto &elem : setmap_points ) {
+        if( elem.has_vehicle_collision( dat, offset ) ) {
+            return true;
+        }
+    }
+
+    return objects.has_vehicle_collision( dat, offset );
+}
+
 /*
  * Apply mapgen as per a derived-from-json recipe; in theory fast, but not very versatile
  */
@@ -7702,7 +7754,7 @@ bool update_mapgen_function_json::update_map( const tripoint &omt_pos, const poi
 {
     tinymap update_tmap;
     const tripoint sm_pos = omt_to_sm_copy( omt_pos );
-    update_tmap.load( sm_pos, false );
+    update_tmap.load( sm_pos, true );
 
     mapgendata md( omt_pos, update_tmap, 0.0f, calendar::start_of_cataclysm, miss );
 
diff --git a/src/mapgen.h b/src/mapgen.h
index 4816d0c48f4e1..e21be63201c30 100644
--- a/src/mapgen.h
+++ b/src/mapgen.h
@@ -279,6 +279,7 @@ class mapgen_function_json_base
     public:
         bool check_inbounds( const jmapgen_int &x, const jmapgen_int &y, const JsonObject &jso ) const;
         size_t calc_index( const point &p ) const;
+        bool has_vehicle_collision( mapgendata &dat, const point &offset ) const;
 
     private:
         std::string jdata;