diff --git a/src/OWLS_Update.cpp b/src/OWLS_Update.cpp
index 7151f3a..6c58f75 100644
--- a/src/OWLS_Update.cpp
+++ b/src/OWLS_Update.cpp
@@ -3,11 +3,8 @@
 //
 #include "OWLSclient.h"
 #include "SimulationRunner.h"
-#include "SimulationCoordinator.h"
-#include <fmt/format.h>
 #include "SimStats.h"
 #include <Poco/NObserver.h>
-
 #include "OWLSclientEvents.h"
 
 namespace OpenWifi::OWLSclientEvents {
diff --git a/src/RESTAPI/RESTAPI_operation_handler.cpp b/src/RESTAPI/RESTAPI_operation_handler.cpp
index 02f290d..56aec01 100644
--- a/src/RESTAPI/RESTAPI_operation_handler.cpp
+++ b/src/RESTAPI/RESTAPI_operation_handler.cpp
@@ -26,6 +26,10 @@ namespace OpenWifi {
 
 		std::string Error;
 		if (Op == "start") {
+            if(SimulationCoordinator()->IsSimulationRunning(Id)) {
+                RESTAPI::Errors::msg    E{.err_num=4001, .err_txt="Simulation is already running."};
+                return BadRequest(E);
+            }
 			SimulationCoordinator()->StartSim(SimId, Id, Error, UserInfo_.userinfo.email);
 		} else if (Op == "stop") {
 			SimulationCoordinator()->StopSim(SimId, Error);
diff --git a/src/SimulationCoordinator.cpp b/src/SimulationCoordinator.cpp
index 4764bd6..f20d311 100644
--- a/src/SimulationCoordinator.cpp
+++ b/src/SimulationCoordinator.cpp
@@ -56,12 +56,17 @@ namespace OpenWifi {
 
 			uint64_t Now = Utils::Now();
             std::lock_guard     G(Mutex_);
-            for(auto &[_,simulation]:Simulations_) {
+
+            for(auto &[id,simulation]:Simulations_) {
                 if (simulation->Details.simulationLength != 0 &&
                     (Now - SimStats()->GetStartTime(simulation->Runner.Id())) > simulation->Details.simulationLength) {
                     std::string Error;
                     simulation->Runner.Stop();
-                    SimStats()->EndSim(simulation->Runner.Id());
+                    SimStats()->EndSim(id);
+                    OWLSObjects::SimulationStatus S;
+                    SimStats()->GetCurrent(id, S);
+                    StorageService()->SimulationResultsDB().CreateRecord(S);
+                    Simulations_.erase(id);
                 }
             }
 		}
@@ -100,6 +105,16 @@ namespace OpenWifi {
         return Res;
     }
 
+    bool SimulationCoordinator::IsSimulationRunning(const std::string &id) {
+        std::lock_guard G(Mutex_);
+
+        for(const auto &[instance_id,simulation]:Simulations_) {
+            if(simulation->Details.id==id)
+                return true;
+        }
+        return false;
+    }
+
 	bool SimulationCoordinator::StartSim(std::string &SimId, const std::string &Id,
 										 std::string &Error, const std::string &Owner) {
         std::lock_guard G(Mutex_);
@@ -130,10 +145,10 @@ namespace OpenWifi {
         }
 
         sim_hint->second->Runner.Stop();
-
 		OWLSObjects::SimulationStatus S;
 		SimStats()->GetCurrent(sim_hint->second->Runner.Id(), S);
 		StorageService()->SimulationResultsDB().CreateRecord(S);
+        Simulations_.erase(sim_hint);
 
 		return true;
 	}
@@ -150,6 +165,7 @@ namespace OpenWifi {
 
         sim_hint->second->Runner.Stop();
 		SimStats()->SetState(sim_hint->second->Runner.Id(),"none");
+        Simulations_.erase(sim_hint);
 
 		return true;
 	}
diff --git a/src/SimulationCoordinator.h b/src/SimulationCoordinator.h
index 7b42a0f..86bad5a 100644
--- a/src/SimulationCoordinator.h
+++ b/src/SimulationCoordinator.h
@@ -65,6 +65,7 @@ namespace OpenWifi {
 
         [[nodiscard]] Poco::JSON::Object::Ptr GetSimConfigurationPtr(uint64_t uuid);
         [[nodiscard]] Poco::JSON::Object::Ptr GetSimCapabilitiesPtr();
+        bool IsSimulationRunning(const std::string &id);
 
 	  private:
 		Poco::Thread Worker_;