diff --git a/docs/ApiValidationRules.md b/docs/ApiValidationRules.md
index 0e6b46f..64bf33a 100644
--- a/docs/ApiValidationRules.md
+++ b/docs/ApiValidationRules.md
@@ -147,6 +147,7 @@ The id field is required, missing fields will not be updated.
     | Field | Validation |
     |-------|------------|
     | eta_berth, etd_berth, lock_time, zone_entry, operations_start, operations_end | if set these values must be in the future|
+    | eta_interval_end, etd_interval_end | if set these values must be in the future. They must be larger than their ETA/ETD counterparts. |
     | remarks, berth_info | must be <= 512 chars |
     | participant_type | must not be BSMD |
 
@@ -188,6 +189,7 @@ shipcall_id, participant_id, participant_type
 
 1. A dataset may only be changed by a user belonging to the same participant as the times dataset is referring to.
 2. See reference and value checking as specified in /times POST.
+3. The shipcall type may not be changed. 
 
 #### Required fields
 
diff --git a/misc/Ampelfunktion.md b/misc/Ampelfunktion.md
index 1274ba7..def1e03 100644
--- a/misc/Ampelfunktion.md
+++ b/misc/Ampelfunktion.md
@@ -32,7 +32,7 @@ ___
 | 0002            | Zeiten für einen Eintrag weichen voneinander ab                       | Bedingungen:<br/> - Header der Zeile ist zugeordnet (Agentur, Festmacher usw. - außer BSMD-Spalte)<br/> - Zeiten ungleich (leere Einträge nicht berücksichtigen => 0001)                                                                                                                                                                                          |             |
 | 0002 - A        | Agentur + Festmacher + Hafenamt + Lotsen + Schlepper / einkommend     |  Schnittmenge aus:<br/>times_agency:<br/> - ETA Berth <br/>____und____<br/>times_mooring:<br/> - ETA Berth <br/>____und____<br/>times_portauthority:<br/>- ETA Berth <br/>____und____<br/>times_pilot:<br/> - ETA Berth <br/>____und____<br/>times_tug:<br/> - ETA Berth                                                                                            | rot         |
 | 0002 - B        | Agentur + Festmacher + Hafenamt + Lotsen + Schlepper / ausgehend      |  Schnittmenge aus:<br/>times_agency:<br/> - ETD Berth <br/>____und____<br/>times_mooring:<br/> - ETD Berth <br/>____und____<br/>times_portauthority:<br/>- ETD Berth <br/>____und____<br/>times_pilot:<br/> - ETD Berth <br/>____und____<br/>times_tug:<br/> - ETD Berth                                                                                            | rot         |
-| 0002 - C        | Agentur + Festmacher + Hafenamt + Lotsen + Schlepper / Verholung      |  Schnittmenge aus:<br />times_agency:<br/> - ETA Berth <br/> - ETD Berth <br/>____und____<br/>times_mooring:<br/> - ETA Berth <br/> - ETD Berth <br/>____und____<br/>times_portauthority:<br/> - ETA Berth <br/>- ETD Berth <br/>____und____<br/>times_pilot:<br/> - ETA Berth <br/> - ETD Berth <br/>____und____<br/>times_tug:<br/> - ETA Berth <br/> - ETD Berth  | rot         |
+| 0002 - C        | Agentur + Festmacher + Hafenamt + Lotsen + Schlepper / Verholung      |  Schnittmenge aus:<br/>times_agency:<br/> - ETD Berth <br/>____und____<br/>times_mooring:<br/> - ETD Berth <br/>____und____<br/>times_portauthority:<br/>- ETD Berth <br/>____und____<br/>times_pilot:<br/> - ETD Berth <br/>____und____<br/>times_tug:<br/> - ETD Berth  | rot         |
 | 0003            | Arbeitszeit überschneidet sich mit Fahrtzeit                          | Bedingungen:<br/> - Header der Zeile ist zugeordnet (Terminal)<br/> - Zeiten passt nicht zu Ankunft / Abfahrt (leere Einträge nicht berücksichtigen => 0001)                                                                                                                                                                                                      |             |
 | 0003 - A        | Terminal / einkommend                                                 | times_terminal:<br/> - Operation Start<br/>___vor (kleiner als)____<br/> times_agency:<br/> - ETA Berth | rot, aktuell __deaktiviert__! |
 | 0003 - B        | Terminal / ausgehend + Verholung                                      | times_terminal:<br/> - Operation Ende<br/>___nach (größer als)____<br/> times_agency:<br/> - ETD Berth  | rot, aktuell __deaktiviert__! |
diff --git a/src/server/BreCal/database/sql_queries.py b/src/server/BreCal/database/sql_queries.py
index 9888ada..e0e9b7e 100644
--- a/src/server/BreCal/database/sql_queries.py
+++ b/src/server/BreCal/database/sql_queries.py
@@ -266,6 +266,11 @@ class SQLQuery():
         query = "SELECT id, name, imo, callsign, participant_id, length, width, is_tug, bollard_pull, eni, created, modified, deleted FROM ship ORDER BY name"
         return query
     
+    @staticmethod
+    def get_ship_by_id()->str:
+        query = "SELECT * FROM ship where id = ?id?"
+        return query
+    
     @staticmethod
     def get_times()->str:
         query = "SELECT id, eta_berth, eta_berth_fixed, etd_berth, etd_berth_fixed, lock_time, lock_time_fixed, " + \
diff --git a/src/server/BreCal/schemas/model.py b/src/server/BreCal/schemas/model.py
index a21fb20..14bceda 100644
--- a/src/server/BreCal/schemas/model.py
+++ b/src/server/BreCal/schemas/model.py
@@ -436,6 +436,21 @@ class TimesSchema(Schema):
         # when 'value' is 'None', a ValidationError is not issued.
         valid_time = validate_time_is_in_not_too_distant_future(raise_validation_error=True, value=value, months=12)
         return
+    
+    @validates("eta_interval_end")
+    def validate_eta_interval_end(self, value):
+        # violation when time is not in the future, but also does not exceed a threshold for the 'reasonable' future
+        # when 'value' is 'None', a ValidationError is not issued.
+        valid_time = validate_time_is_in_not_too_distant_future(raise_validation_error=True, value=value, months=12)
+        return
+
+    @validates("etd_interval_end")
+    def validate_etd_interval_end(self, value):
+        # violation when time is not in the future, but also does not exceed a threshold for the 'reasonable' future
+        # when 'value' is 'None', a ValidationError is not issued.
+        valid_time = validate_time_is_in_not_too_distant_future(raise_validation_error=True, value=value, months=12)
+        return
+
 
 # deserialize PUT object target
 
diff --git a/src/server/BreCal/stubs/times.py b/src/server/BreCal/stubs/times.py
new file mode 100644
index 0000000..a26b659
--- /dev/null
+++ b/src/server/BreCal/stubs/times.py
@@ -0,0 +1,12 @@
+import datetime
+from BreCal.schemas import model
+from BreCal.schemas.model import ParticipantType
+
+def get_schema_model_stub_departure():
+    schemaModel = {'id': 0, 'eta_berth': None, 'eta_berth_fixed': None, 'etd_berth': datetime.datetime(2024, 9, 7, 15, 12, 58), 'etd_berth_fixed': None, 'lock_time': None, 'lock_time_fixed': None, 'zone_entry': None, 'zone_entry_fixed': None, 'operations_start': None, 'operations_end': None, 'remarks': 'test', 'participant_id': 10, 'berth_id': 146, 'berth_info': '', 'pier_side': None, 'shipcall_id': 115, 'participant_type': ParticipantType.AGENCY, 'ata': None, 'atd': None, 'eta_interval_end': None, 'etd_interval_end': None, 'created': None, 'modified': None}
+    return schemaModel
+
+def get_schema_model_stub_arrival():
+    schemaModel = {'id': 0, 'eta_berth': datetime.datetime(2024, 9, 7, 15, 12, 58), 'eta_berth_fixed': None, 'etd_berth': None, 'etd_berth_fixed': None, 'lock_time': None, 'lock_time_fixed': None, 'zone_entry': None, 'zone_entry_fixed': None, 'operations_start': None, 'operations_end': None, 'remarks': 'test', 'participant_id': 10, 'berth_id': 146, 'berth_info': '', 'pier_side': None, 'shipcall_id': 115, 'participant_type': ParticipantType.AGENCY, 'ata': None, 'atd': None, 'eta_interval_end': None, 'etd_interval_end': None, 'created': None, 'modified': None}
+    return schemaModel
+
diff --git a/src/server/BreCal/validators/input_validation_ship.py b/src/server/BreCal/validators/input_validation_ship.py
index 47fa918..3a47b2c 100644
--- a/src/server/BreCal/validators/input_validation_ship.py
+++ b/src/server/BreCal/validators/input_validation_ship.py
@@ -6,6 +6,8 @@ from marshmallow import ValidationError
 from string import ascii_letters, digits
 
 from BreCal.schemas.model import Ship, Shipcall, Berth, User, Participant, ShipcallType
+from BreCal.database.sql_handler import execute_sql_query_standalone    
+from BreCal.database.sql_queries import SQLQuery
 from BreCal.impl.participant import GetParticipant
 from BreCal.impl.ships import GetShips
 from BreCal.impl.berths import GetBerths
@@ -47,14 +49,14 @@ class InputValidationShip():
         # 1.) Only users of type BSMD are allowed to PUT
         InputValidationShip.check_user_is_bsmd_type(user_data)
 
-        # 2.) The IMO number field may not be changed
+        # 2.) ID field is mandatory
+        InputValidationShip.content_contains_ship_id(content)
+
+        # 3.) The IMO number field may not be changed
         InputValidationShip.put_content_may_not_contain_imo_number(content)
 
-        # 3.) Check for reasonable Values (see BreCal.schemas.model.ShipSchema)
+        # 4.) Check for reasonable Values (see BreCal.schemas.model.ShipSchema)
         InputValidationShip.optionally_evaluate_bollard_pull_value(content)
-
-        # 4.) ID field is mandatory
-        InputValidationShip.content_contains_ship_id(content)
         return
     
     @staticmethod
@@ -101,11 +103,15 @@ class InputValidationShip():
     
     @staticmethod
     def put_content_may_not_contain_imo_number(content:dict):
+        # IMO is a required field, so it will never be None outside of tests. If so, there is no violation
         put_data_ship_imo = content.get("imo",None)
+        if put_data_ship_imo is None:
+            return
+        
+        # grab the ship by its ID and compare, whether the IMO is unchanged
+        ship = execute_sql_query_standalone(SQLQuery.get_ship_by_id(), param={"id":content.get("id")}, command_type="single", model=Ship)
 
-        # #TODO: Aktuelle IMO abfragen und nach Änderung suchen, bevor eine Fehlermeldung erstellt wird
-
-        if put_data_ship_imo is not None:
+        if put_data_ship_imo != ship.imo:
             raise ValidationError(f"The IMO number field may not be changed since it serves the purpose of a primary (matching) key.")
         return
     
diff --git a/src/server/BreCal/validators/input_validation_shipcall.py b/src/server/BreCal/validators/input_validation_shipcall.py
index 729a896..59b8b35 100644
--- a/src/server/BreCal/validators/input_validation_shipcall.py
+++ b/src/server/BreCal/validators/input_validation_shipcall.py
@@ -123,6 +123,9 @@ class InputValidationShipcall():
         # time values must use future-dates
         InputValidationShipcall.check_times_are_in_future(loadedModel, content)
 
+        # the type of a shipcall may not be changed. It can only be set with the initial POST-request.
+        InputValidationShipcall.check_shipcall_type_is_unchanged(loadedModel)
+
         # some arguments must not be provided
         InputValidationShipcall.check_forbidden_arguments(content, forbidden_keys=forbidden_keys)
         return
@@ -247,6 +250,16 @@ class InputValidationShipcall():
         if not valid_participant_types: # #TODO: according to Daniel, there may eventually be multi-assignment of participants for the same role
             raise ValidationError(f"every participant id and type should be listed only once. Found multiple entries for one of the participants.")
         
+    @staticmethod
+    def check_shipcall_type_is_unchanged(loadedModel:dict):
+        # the type of a shipcall may only be set on POST requests. Afterwards, shipcall types may not be changed.
+        query = SQLQuery.get_shipcall_by_id()
+        shipcall = execute_sql_query_standalone(query=query, model=Shipcall, param={"id":loadedModel.get("id")}, command_type="single")
+
+        if int(loadedModel["type"]) != int(shipcall.type):
+            raise ValidationError(f"The shipcall type may only be set in the initial POST-request. Afterwards, changing the shipcall type is not allowed.") # @pytest.raises
+        return
+        
     @staticmethod
     def check_forbidden_arguments(content:dict, forbidden_keys=["evaluation", "evaluation_message"]):
         """
diff --git a/src/server/BreCal/validators/input_validation_times.py b/src/server/BreCal/validators/input_validation_times.py
index 0385220..688c651 100644
--- a/src/server/BreCal/validators/input_validation_times.py
+++ b/src/server/BreCal/validators/input_validation_times.py
@@ -29,32 +29,32 @@ def build_post_data_type_dependent_required_fields_dict()->dict[ShipcallType,dic
         ShipcallType.arrival:{
             ParticipantType.undefined:[], # should not be set in POST requests
             ParticipantType.BSMD:[], # should not be set in POST requests
-            ParticipantType.TERMINAL:["operations_start"],
-            ParticipantType.AGENCY:["eta_berth"],
-            ParticipantType.MOORING:["eta_berth"],
-            ParticipantType.PILOT:["eta_berth"],
-            ParticipantType.PORT_ADMINISTRATION:["eta_berth"],
-            ParticipantType.TUG:["eta_berth"],
+            ParticipantType.TERMINAL:[],
+            ParticipantType.AGENCY:[],
+            ParticipantType.MOORING:[],
+            ParticipantType.PILOT:[],
+            ParticipantType.PORT_ADMINISTRATION:[],
+            ParticipantType.TUG:[],
         },
         ShipcallType.departure:{
             ParticipantType.undefined:[], # should not be set in POST requests
             ParticipantType.BSMD:[], # should not be set in POST requests
-            ParticipantType.TERMINAL:["operations_end"],
-            ParticipantType.AGENCY:["etd_berth"],
-            ParticipantType.MOORING:["etd_berth"],
-            ParticipantType.PILOT:["etd_berth"],
-            ParticipantType.PORT_ADMINISTRATION:["etd_berth"],
-            ParticipantType.TUG:["etd_berth"],
+            ParticipantType.TERMINAL:[],
+            ParticipantType.AGENCY:[],
+            ParticipantType.MOORING:[],
+            ParticipantType.PILOT:[],
+            ParticipantType.PORT_ADMINISTRATION:[],
+            ParticipantType.TUG:[],
         },
         ShipcallType.shifting:{
             ParticipantType.undefined:[], # should not be set in POST requests
             ParticipantType.BSMD:[], # should not be set in POST requests
-            ParticipantType.TERMINAL:["operations_start", "operations_end"],
-            ParticipantType.AGENCY:["eta_berth", "etd_berth"],
-            ParticipantType.MOORING:["eta_berth", "etd_berth"],
-            ParticipantType.PILOT:["eta_berth", "etd_berth"],
-            ParticipantType.PORT_ADMINISTRATION:["eta_berth", "etd_berth"],
-            ParticipantType.TUG:["eta_berth", "etd_berth"],
+            ParticipantType.TERMINAL:[],
+            ParticipantType.AGENCY:[],
+            ParticipantType.MOORING:[],
+            ParticipantType.PILOT:[],
+            ParticipantType.PORT_ADMINISTRATION:[],
+            ParticipantType.TUG:[],
         },
     }
     return post_data_type_dependent_required_fields_dict
@@ -167,6 +167,17 @@ class InputValidationTimes():
 
         if ParticipantType.BSMD in loadedModel["participant_type"]:
             raise ValidationError(f"current user belongs to BSMD. Cannot post times datasets. Found user data: {user_data}")
+        
+        if (loadedModel["etd_interval_end"] is not None) and (loadedModel["etd_berth"] is not None):
+            time_end_after_time_start = loadedModel["etd_interval_end"] >= loadedModel["etd_berth"]
+            if not time_end_after_time_start:
+                raise ValidationError(f"The provided time interval for the estimated departure time is invalid. The interval end takes place before the interval start. Found interval data: {loadedModel['etd_berth']} to {loadedModel['etd_interval_end']}")
+
+
+        if (loadedModel["eta_interval_end"] is not None) and (loadedModel["eta_berth"] is not None):
+            time_end_after_time_start = loadedModel["eta_interval_end"] >= loadedModel["eta_berth"]
+            if not time_end_after_time_start:
+                raise ValidationError(f"The provided time interval for the estimated arrival time is invalid. The interval begin takes place after the interval end. Found interval data: {loadedModel['eta_berth']} to {loadedModel['eta_interval_end']}")
         return
     
     @staticmethod
@@ -471,3 +482,44 @@ class InputValidationTimes():
         has_bsmd_flag = ParticipantFlag.BSMD in [ParticipantFlag(participant.get("flags"))]
         return has_bsmd_flag
 
+
+def deprecated_build_post_data_type_dependent_required_fields_dict()->dict[ShipcallType,dict[ParticipantType,typing.Optional[list[str]]]]:
+    """
+    The required fields of a POST-request depend on ShipcallType and ParticipantType. This function creates
+    a dictionary, which maps those types to a list of required fields.
+
+    The participant types 'undefined' and 'bsmd' should not be used in POST-requests. They return 'None'. 
+    """
+    post_data_type_dependent_required_fields_dict = {
+        ShipcallType.arrival:{
+            ParticipantType.undefined:[], # should not be set in POST requests
+            ParticipantType.BSMD:[], # should not be set in POST requests
+            ParticipantType.TERMINAL:[],
+            ParticipantType.AGENCY:["eta_berth"],
+            ParticipantType.MOORING:["eta_berth"],
+            ParticipantType.PILOT:["eta_berth"],
+            ParticipantType.PORT_ADMINISTRATION:["eta_berth"],
+            ParticipantType.TUG:["eta_berth"],
+        },
+        ShipcallType.departure:{
+            ParticipantType.undefined:[], # should not be set in POST requests
+            ParticipantType.BSMD:[], # should not be set in POST requests
+            ParticipantType.TERMINAL:[],
+            ParticipantType.AGENCY:["etd_berth"],
+            ParticipantType.MOORING:["etd_berth"],
+            ParticipantType.PILOT:["etd_berth"],
+            ParticipantType.PORT_ADMINISTRATION:["etd_berth"],
+            ParticipantType.TUG:["etd_berth"],
+        },
+        ShipcallType.shifting:{
+            ParticipantType.undefined:[], # should not be set in POST requests
+            ParticipantType.BSMD:[], # should not be set in POST requests
+            ParticipantType.TERMINAL:[],
+            ParticipantType.AGENCY:["etd_berth"],
+            ParticipantType.MOORING:["etd_berth"],
+            ParticipantType.PILOT:["etd_berth"],
+            ParticipantType.PORT_ADMINISTRATION:["etd_berth"],
+            ParticipantType.TUG:["etd_berth"],
+        },
+    }
+    return post_data_type_dependent_required_fields_dict
diff --git a/src/server/BreCal/validators/validation_error.py b/src/server/BreCal/validators/validation_error.py
index cdac103..65ee985 100644
--- a/src/server/BreCal/validators/validation_error.py
+++ b/src/server/BreCal/validators/validation_error.py
@@ -27,8 +27,15 @@ def create_validation_error_response(ex:ValidationError, status_code:int=400)->t
         "errors":errors,
         "valid_data":valid_data
     }
-    return (json.dumps(json_response), status_code)
+
+    # json.dumps with default=str automatically converts non-serializable values to strings. Hence, datetime objects (which are not)
+    # natively serializable are properly serialized.
+    serialized_response = json.dumps(json_response, default=str)
+    return (serialized_response, status_code)
 
 def create_werkzeug_error_response(ex:Forbidden, status_code:int=403)->typing.Tuple[str,int]:
-    return json.dumps({"message":ex.description}), status_code
+    # json.dumps with default=str automatically converts non-serializable values to strings. Hence, datetime objects (which are not)
+    # natively serializable are properly serialized.
+    serialized_response = json.dumps({"message":ex.description}, default=str)
+    return serialized_response, status_code
 
diff --git a/src/server/BreCal/validators/validation_rule_functions.py b/src/server/BreCal/validators/validation_rule_functions.py
index ae3e3bc..b035345 100644
--- a/src/server/BreCal/validators/validation_rule_functions.py
+++ b/src/server/BreCal/validators/validation_rule_functions.py
@@ -27,7 +27,7 @@ error_message_dict = {
     # 0002 A+B+C
     "validation_rule_fct_shipcall_incoming_participants_disagree_on_eta":"There are deviating times between agency, mooring, port authority, pilot and tug for the estimated time of arrival (ETA) {Rule #0002A}",
     "validation_rule_fct_shipcall_outgoing_participants_disagree_on_etd":"There are deviating times between agency, mooring, port authority, pilot and tug for the estimated time of departure (ETD) {Rule #0002B}",
-    "validation_rule_fct_shipcall_shifting_participants_disagree_on_eta_or_etd":"There are deviating times between agency, mooring, port authority, pilot and tug for ETA and ETD {Rule #0002C}",
+    "validation_rule_fct_shipcall_shifting_participants_disagree_on_etd":"There are deviating times between agency, mooring, port authority, pilot and tug for the estimated time of departure (ETD) {Rule #0002C}",
 
     # 0003 A+B
     "validation_rule_fct_eta_time_not_in_operation_window":"The estimated time of arrival will be AFTER the planned start of operations. {Rule #0003A}",
@@ -723,21 +723,13 @@ class ValidationRuleFunctions(ValidationRuleBaseFunctions):
         else:
             return self.get_no_violation_default_output()
 
-    def validation_rule_fct_shipcall_shifting_participants_disagree_on_eta_or_etd(self, shipcall, df_times, *args, **kwargs):
+    def validation_rule_fct_shipcall_shifting_participants_disagree_on_etd(self, shipcall, df_times, *args, **kwargs):
         """
         Code: #0002-C
         Type: Local Rule
-        Description: this validation checks, whether the participants expect different ETA or ETD times
+        Description: this validation checks, whether the participants expect different ETD times
         Filter: only applies to shifting shipcalls
         """
-        violation_state_eta = self.check_participants_agree_on_estimated_time(
-            shipcall = shipcall,
-
-            query="eta_berth",
-            df_times=df_times,
-            applicable_shipcall_type=ShipcallType.SHIFTING
-            )
-
         violation_state_etd = self.check_participants_agree_on_estimated_time(
             shipcall = shipcall,
 
@@ -746,16 +738,14 @@ class ValidationRuleFunctions(ValidationRuleBaseFunctions):
             applicable_shipcall_type=ShipcallType.SHIFTING
             )
 
-        # apply 'eta_berth' check
         # apply 'etd_berth'
-        # violation: if either 'eta_berth' or 'etd_berth' is violated
+        # violation: if either 'etd_berth' is violated
         # functionally, this is the same as individually comparing all times for the participants
-        #    times_agency.eta_berth==times_mooring.eta_berth==times_portadministration.eta_berth==times_pilot.eta_berth==times_tug.eta_berth
         #    times_agency.etd_berth==times_mooring.etd_berth==times_portadministration.etd_berth==times_pilot.etd_berth==times_tug.etd_berth
-        violation_state = (violation_state_eta) or (violation_state_etd)
+        violation_state = (violation_state_etd)
 
         if violation_state:
-            validation_name = "validation_rule_fct_shipcall_shifting_participants_disagree_on_eta_or_etd"
+            validation_name = "validation_rule_fct_shipcall_shifting_participants_disagree_on_etd"
             return (StatusFlags.RED, validation_name)
         else:
             return self.get_no_violation_default_output()
diff --git a/src/server/tests/database/test_sql_queries.py b/src/server/tests/database/test_sql_queries.py
index fc4267a..9db3d75 100644
--- a/src/server/tests/database/test_sql_queries.py
+++ b/src/server/tests/database/test_sql_queries.py
@@ -87,6 +87,13 @@ def test_sql_get_ships():
     assert all([isinstance(ship, model.Ship) for ship in ships])
     return
 
+def test_sql_get_ship_by_id():
+    query =  #"SELECT * FROM ship where id = ?id?" # #TODO_refactor: put into the SQLQuery object
+    ship = execute_sql_query_standalone(SQLQuery.get_ship_by_id(), param={"id":1}, command_type="single", model=model.Ship)
+    assert isinstance(ship, model.Ship)
+    return
+
+
 def test_sql_get_times():
     options = {'shipcall_id':153}
     times = execute_sql_query_standalone(query=SQLQuery.get_times(), model=model.Times, param={"scid" : options["shipcall_id"]})
diff --git a/src/server/tests/validators/test_input_validation_shipcall.py b/src/server/tests/validators/test_input_validation_shipcall.py
index df41f1f..87b3b7f 100644
--- a/src/server/tests/validators/test_input_validation_shipcall.py
+++ b/src/server/tests/validators/test_input_validation_shipcall.py
@@ -901,3 +901,35 @@ def test_post_data_with_valid_data(get_stub_token):
     assert response.status_code==201
     return
 
+def test_input_validation_shipcall_put_fails_when_type_differs():
+    from marshmallow import ValidationError
+    from BreCal.stubs.shipcall import get_stub_valid_shipcall_arrival
+    from BreCal.schemas import model
+    from BreCal.database.sql_queries import SQLQuery
+    from BreCal.database.sql_handler import execute_sql_query_standalone
+
+    from BreCal.validators.input_validation_shipcall import InputValidationShipcall
+
+    # stub data
+    put_data = get_stub_valid_shipcall_arrival()
+    put_data["id"] = 3
+    loadedModel = model.ShipcallSchema().load(data=put_data, many=False, partial=True)
+
+    # load data from DB
+    shipcall_id = loadedModel.get("id")
+    query = SQLQuery.get_shipcall_by_id()
+    shipcall = execute_sql_query_standalone(query=query, model=model.Shipcall, param={"id":shipcall_id}, command_type="single")
+
+    # create failure case. Ensures that the type is not the same as in the loaded shipcall from the DB
+    failure_case = 1 if shipcall.type==2 else 2
+    loadedModel["type"] = model.ShipcallType(failure_case)
+
+    # should fail: different 'type'
+    with pytest.raises(ValidationError, match="The shipcall type may only be set in the initial POST-request. Afterwards, changing the shipcall type is not allowed"):
+        InputValidationShipcall.check_shipcall_type_is_unchanged(loadedModel)
+
+    # should pass: same 'type'
+    loadedModel["type"] = shipcall.type
+    InputValidationShipcall.check_shipcall_type_is_unchanged(loadedModel)
+    return
+
diff --git a/src/server/tests/validators/test_input_validation_times.py b/src/server/tests/validators/test_input_validation_times.py
index 550387a..7a9b7d5 100644
--- a/src/server/tests/validators/test_input_validation_times.py
+++ b/src/server/tests/validators/test_input_validation_times.py
@@ -409,3 +409,60 @@ def test_input_validation_times_delete_request_fails_when_user_belongs_to_wrong_
     InputValidationTimes.check_user_belongs_to_same_group_as_dataset_determines(user_data, loadedModel=None, times_id=times_id, pdata=pdata)
     return
 
+def test_input_validation_times_check_dataset_values_for_time_intervals():
+    import datetime
+    from BreCal.schemas import model
+    from BreCal.validators.input_validation_times import InputValidationTimes
+    from BreCal.stubs.times import get_schema_model_stub_arrival, get_schema_model_stub_departure
+    from marshmallow import ValidationError
+
+    ### ETD (departure)
+    # expected to pass
+    schemaModel = get_schema_model_stub_departure()
+    schemaModel["etd_interval_end"] = schemaModel["etd_berth"] + datetime.timedelta(minutes=2)
+
+    schemaModel["etd_berth"] = schemaModel["etd_berth"].isoformat()
+    schemaModel["etd_interval_end"] = schemaModel["etd_interval_end"].isoformat()
+    content = schemaModel
+    loadedModel = model.TimesSchema().load(data=schemaModel, many=False, partial=True)
+
+    InputValidationTimes.check_dataset_values(user_data={}, loadedModel=loadedModel, content=content)
+
+    # expected to fail: the from-to-interval is incorrectly set.
+    schemaModel = get_schema_model_stub_departure()
+    schemaModel["etd_interval_end"] = schemaModel["etd_berth"] - datetime.timedelta(minutes=2)
+
+    schemaModel["etd_berth"] = schemaModel["etd_berth"].isoformat()
+    schemaModel["etd_interval_end"] = schemaModel["etd_interval_end"].isoformat()
+    content = schemaModel
+    loadedModel = model.TimesSchema().load(data=schemaModel, many=False, partial=True)
+
+    with pytest.raises(ValidationError, match="The provided time interval for the estimated departure time is invalid"):
+        InputValidationTimes.check_dataset_values(user_data={}, loadedModel=loadedModel, content=content)
+
+
+    ### ETA (arrival)
+    # expected to pass
+    schemaModel = get_schema_model_stub_arrival()
+    schemaModel["eta_interval_end"] = schemaModel["eta_berth"] + datetime.timedelta(minutes=2)
+
+    schemaModel["eta_berth"] = schemaModel["eta_berth"].isoformat()
+    schemaModel["eta_interval_end"] = schemaModel["eta_interval_end"].isoformat()
+    content = schemaModel
+    loadedModel = model.TimesSchema().load(data=schemaModel, many=False, partial=True)
+
+    InputValidationTimes.check_dataset_values(user_data={}, loadedModel=loadedModel, content=content)
+
+    # expected to fail: the from-to-interval is incorrectly set.
+    schemaModel = get_schema_model_stub_arrival()
+    schemaModel["eta_interval_end"] = schemaModel["eta_berth"] - datetime.timedelta(minutes=2)
+
+    schemaModel["eta_berth"] = schemaModel["eta_berth"].isoformat()
+    schemaModel["eta_interval_end"] = schemaModel["eta_interval_end"].isoformat()
+    content = schemaModel
+    loadedModel = model.TimesSchema().load(data=schemaModel, many=False, partial=True)
+
+    with pytest.raises(ValidationError, match="The provided time interval for the estimated arrival time is invalid"):
+        InputValidationTimes.check_dataset_values(user_data={}, loadedModel=loadedModel, content=content)
+    return
+
diff --git a/src/server/tests/validators/test_validation_error.py b/src/server/tests/validators/test_validation_error.py
new file mode 100644
index 0000000..a103919
--- /dev/null
+++ b/src/server/tests/validators/test_validation_error.py
@@ -0,0 +1,19 @@
+import pytest
+
+def test_create_validation_error_response_is_serializable():
+    from BreCal.stubs.times_full import get_valid_stub_times
+    from BreCal.schemas import model
+    from BreCal.validators.validation_error import create_validation_error_response
+
+    content = get_valid_stub_times()
+
+    import datetime
+    content["operations_end"] = (datetime.datetime.now()-datetime.timedelta(minutes=14)).isoformat()
+
+    content["id"] = 3
+    try:
+        loadedModel = model.TimesSchema().load(data=content, many=False, partial=True)
+    except Exception as ex:
+        my_var = ex
+        create_validation_error_response(ex=ex, status_code=400) # this function initially created errors, as datetime objects were not serializable. Corrected now.
+    return