diff --git a/front/src/applications/operationalStudies/components/MacroEditor/ngeToOsrd.ts b/front/src/applications/operationalStudies/components/MacroEditor/ngeToOsrd.ts
index c3e748c6ebc..51a91367303 100644
--- a/front/src/applications/operationalStudies/components/MacroEditor/ngeToOsrd.ts
+++ b/front/src/applications/operationalStudies/components/MacroEditor/ngeToOsrd.ts
@@ -8,7 +8,7 @@ import {
 } from 'common/api/osrdEditoastApi';
 import type { AppDispatch } from 'store';
 import { formatToIsoDate } from 'utils/date';
-import { calculateTimeDifferenceInSeconds, formatDurationAsISO8601 } from 'utils/timeManipulation';
+import { Duration } from 'utils/duration';
 
 import type MacroEditorState from './MacroEditorState';
 import type { NodeIndexed } from './MacroEditorState';
@@ -157,7 +157,7 @@ const getTimeLockDate = (
 };
 
 const formatDateDifference = (start: Date, stop: Date) =>
-  formatDurationAsISO8601(calculateTimeDifferenceInSeconds(start, stop));
+  Duration.subtractDate(stop, start).toISOString();
 
 const createTrainSchedulePayload = async ({
   trainrunSections,
diff --git a/front/src/modules/trainschedule/components/ImportTrainSchedule/generateTrainSchedulesPayloads.ts b/front/src/modules/trainschedule/components/ImportTrainSchedule/generateTrainSchedulesPayloads.ts
index 425f90ea660..06cc096fbd9 100644
--- a/front/src/modules/trainschedule/components/ImportTrainSchedule/generateTrainSchedulesPayloads.ts
+++ b/front/src/modules/trainschedule/components/ImportTrainSchedule/generateTrainSchedulesPayloads.ts
@@ -4,7 +4,7 @@ import nextId from 'react-id-generator';
 import type { ImportedTrainSchedule } from 'applications/operationalStudies/types';
 import type { TrainScheduleBase } from 'common/api/osrdEditoastApi';
 import { formatToIsoDate } from 'utils/date';
-import { calculateTimeDifferenceInSeconds, formatDurationAsISO8601 } from 'utils/timeManipulation';
+import { Duration } from 'utils/duration';
 
 export function generateTrainSchedulesPayloads(
   trains: ImportedTrainSchedule[],
@@ -19,6 +19,8 @@ export function generateTrainSchedulesPayloads(
       return payloads; // Skip this train
     }
 
+    const departureTime = new Date(train.departureTime);
+
     const { path, schedule } = train.steps.reduce(
       (acc, step, index) => {
         const stepId = nextId();
@@ -37,13 +39,10 @@ export function generateTrainSchedulesPayloads(
 
         // Skip first step, handle time differences
         if (index !== 0) {
-          const timeDifferenceInSeconds = calculateTimeDifferenceInSeconds(
-            train.departureTime,
-            step.arrivalTime
-          );
+          const arrivalTime = new Date(step.arrivalTime);
           const schedulePoint: NonNullable<TrainScheduleBase['schedule']>[number] = {
             at: stepId,
-            arrival: formatDurationAsISO8601(timeDifferenceInSeconds),
+            arrival: Duration.subtractDate(arrivalTime, departureTime).toISOString(),
             stop_for: step.duration ? `PT${step.duration}S` : undefined,
           };
           acc.schedule.push(schedulePoint);
diff --git a/front/src/utils/timeManipulation.ts b/front/src/utils/timeManipulation.ts
index 8b500791db0..befdad3c6ec 100644
--- a/front/src/utils/timeManipulation.ts
+++ b/front/src/utils/timeManipulation.ts
@@ -77,10 +77,6 @@ export function calculateTimeDifferenceInDays(datetime1?: Date, datetime2?: Date
   return dayjs.duration(date2.getTime() - date1.getTime()).asDays();
 }
 
-export function formatDurationAsISO8601(seconds: number) {
-  return `PT${Math.abs(seconds)}S`;
-}
-
 /**
  * Parse ISO8601 duration, for instance "PT11H9M8S" (11h, 9min and 8s) to seconds
  */