diff --git a/src/ai/api/ai_changelog.hpp b/src/ai/api/ai_changelog.hpp
index d77cb03c24..67875146ea 100644
--- a/src/ai/api/ai_changelog.hpp
+++ b/src/ai/api/ai_changelog.hpp
@@ -27,6 +27,7 @@
  * \li AICompany::GetQuarterlyPerformanceRating
  * \li AICompany::GetQuarterlyCompanyValue
  * \li AITown::GetTownAuthority
+ * \li AIVehicle::ERR_VEHICLE_TOO_LONG in case vehicle length limit is reached
  *
  * API removals:
  * \li AICompany::GetCompanyValue, use AICompany::GetQuarterlyCompanyValue instead.
diff --git a/src/ai/api/ai_vehicle.hpp b/src/ai/api/ai_vehicle.hpp
index 7bd9120d10..bbcaac8b03 100644
--- a/src/ai/api/ai_vehicle.hpp
+++ b/src/ai/api/ai_vehicle.hpp
@@ -65,6 +65,8 @@ public:
 		/** Vehicle is without power */
 		ERR_VEHICLE_NO_POWER,                   // [STR_ERROR_TRAIN_START_NO_POWER]
 
+		/** Vehicle would get too long during construction. */
+		ERR_VEHICLE_TOO_LONG,                   // [STR_ERROR_TRAIN_TOO_LONG]
 	};
 
 	/**
diff --git a/src/ai/api/ai_vehicle.hpp.sq b/src/ai/api/ai_vehicle.hpp.sq
index 1733fd25fb..933233eaf5 100644
--- a/src/ai/api/ai_vehicle.hpp.sq
+++ b/src/ai/api/ai_vehicle.hpp.sq
@@ -47,6 +47,7 @@ void SQAIVehicle_Register(Squirrel *engine)
 	SQAIVehicle.DefSQConst(engine, AIVehicle::ERR_VEHICLE_NOT_IN_DEPOT,         "ERR_VEHICLE_NOT_IN_DEPOT");
 	SQAIVehicle.DefSQConst(engine, AIVehicle::ERR_VEHICLE_IN_FLIGHT,            "ERR_VEHICLE_IN_FLIGHT");
 	SQAIVehicle.DefSQConst(engine, AIVehicle::ERR_VEHICLE_NO_POWER,             "ERR_VEHICLE_NO_POWER");
+	SQAIVehicle.DefSQConst(engine, AIVehicle::ERR_VEHICLE_TOO_LONG,             "ERR_VEHICLE_TOO_LONG");
 	SQAIVehicle.DefSQConst(engine, AIVehicle::VT_RAIL,                          "VT_RAIL");
 	SQAIVehicle.DefSQConst(engine, AIVehicle::VT_ROAD,                          "VT_ROAD");
 	SQAIVehicle.DefSQConst(engine, AIVehicle::VT_WATER,                         "VT_WATER");
@@ -95,6 +96,7 @@ void SQAIVehicle_Register(Squirrel *engine)
 	AIError::RegisterErrorMap(STR_ERROR_SHIP_MUST_BE_STOPPED_INSIDE_DEPOT,                   AIVehicle::ERR_VEHICLE_NOT_IN_DEPOT);
 	AIError::RegisterErrorMap(STR_ERROR_AIRCRAFT_IS_IN_FLIGHT,                               AIVehicle::ERR_VEHICLE_IN_FLIGHT);
 	AIError::RegisterErrorMap(STR_ERROR_TRAIN_START_NO_POWER,                                AIVehicle::ERR_VEHICLE_NO_POWER);
+	AIError::RegisterErrorMap(STR_ERROR_TRAIN_TOO_LONG,                                      AIVehicle::ERR_VEHICLE_TOO_LONG);
 
 	AIError::RegisterErrorMapString(AIVehicle::ERR_VEHICLE_TOO_MANY,             "ERR_VEHICLE_TOO_MANY");
 	AIError::RegisterErrorMapString(AIVehicle::ERR_VEHICLE_NOT_AVAILABLE,        "ERR_VEHICLE_NOT_AVAILABLE");
@@ -108,6 +110,7 @@ void SQAIVehicle_Register(Squirrel *engine)
 	AIError::RegisterErrorMapString(AIVehicle::ERR_VEHICLE_NOT_IN_DEPOT,         "ERR_VEHICLE_NOT_IN_DEPOT");
 	AIError::RegisterErrorMapString(AIVehicle::ERR_VEHICLE_IN_FLIGHT,            "ERR_VEHICLE_IN_FLIGHT");
 	AIError::RegisterErrorMapString(AIVehicle::ERR_VEHICLE_NO_POWER,             "ERR_VEHICLE_NO_POWER");
+	AIError::RegisterErrorMapString(AIVehicle::ERR_VEHICLE_TOO_LONG,             "ERR_VEHICLE_TOO_LONG");
 
 	SQAIVehicle.DefSQStaticMethod(engine, &AIVehicle::IsValidVehicle,                 "IsValidVehicle",                 2, ".i");
 	SQAIVehicle.DefSQStaticMethod(engine, &AIVehicle::GetNumWagons,                   "GetNumWagons",                   2, ".i");