diff --git a/src/repositories/shuttle/eta/ETAGetterRepository.ts b/src/repositories/shuttle/eta/ETAGetterRepository.ts
new file mode 100644
index 0000000..a1f8255
--- /dev/null
+++ b/src/repositories/shuttle/eta/ETAGetterRepository.ts
@@ -0,0 +1,37 @@
+import { EventEmitter } from "stream";
+import { IEta } from "../../../entities/ShuttleRepositoryEntities";
+
+// TODO: Remove these events in ShuttleGetterRepository
+
+export const ETARepositoryEvent = {
+  ETA_UPDATED: "etaUpdated",
+  ETA_REMOVED: "etaRemoved",
+  ETA_DATA_CLEARED: "etaDataCleared",
+} as const;
+
+export type ETARepositoryEventName = typeof ETARepositoryEvent[keyof typeof ETARepositoryEvent];
+
+export type EtaRemovedEventPayload = IEta;
+export type EtaDataClearedEventPayload = IEta[];
+
+export interface ETARepositoryEventPayloads {
+  [ETARepositoryEvent.ETA_UPDATED]: IEta;
+  [ETARepositoryEvent.ETA_REMOVED]: EtaRemovedEventPayload;
+  [ETARepositoryEvent.ETA_DATA_CLEARED]: EtaDataClearedEventPayload;
+}
+
+export type ETARepositoryEventListener<T extends ETARepositoryEventName> = (
+  payload: ETARepositoryEventPayloads[T],
+) => void;
+
+export interface ETAGetterRepository extends EventEmitter {
+  on<T extends ETARepositoryEventName>(event: T, listener: ETARepositoryEventListener<T>): this;
+  once<T extends ETARepositoryEventName>(event: T, listener: ETARepositoryEventListener<T>): this;
+  off<T extends ETARepositoryEventName>(event: T, listener: ETARepositoryEventListener<T>): this;
+  addListener<T extends ETARepositoryEventName>(event: T, listener: ETARepositoryEventListener<T>): this;
+  removeListener<T extends ETARepositoryEventName>(event: T, listener: ETARepositoryEventListener<T>): this;
+
+  getEtasForShuttleId(shuttleId: string): Promise<IEta[]>;
+  getEtasForStopId(stopId: string): Promise<IEta[]>;
+  getEtaForShuttleAndStopId(shuttleId: string, stopId: string): Promise<IEta | null>;
+}
diff --git a/src/repositories/shuttle/eta/ETAGetterSetterRepository.ts b/src/repositories/shuttle/eta/ETAGetterSetterRepository.ts
new file mode 100644
index 0000000..53dfe5d
--- /dev/null
+++ b/src/repositories/shuttle/eta/ETAGetterSetterRepository.ts
@@ -0,0 +1,11 @@
+import { IEta } from "../../../entities/ShuttleRepositoryEntities";
+import { ETAGetterRepository } from "./ETAGetterRepository";
+
+export interface ExternalSourceETARepository extends ETAGetterRepository {
+  /**
+   * Add or update an ETA from an external source (e.g., API or test data).
+   */
+  addOrUpdateEtaFromExternalSource(eta: IEta): Promise<void>;
+
+  removeEtaIfExists(shuttleId: string, stopId: string): Promise<IEta | null>;
+}
diff --git a/src/repositories/shuttle/eta/SelfUpdatingETARepository.ts b/src/repositories/shuttle/eta/SelfUpdatingETARepository.ts
new file mode 100644
index 0000000..7f2c9f0
--- /dev/null
+++ b/src/repositories/shuttle/eta/SelfUpdatingETARepository.ts
@@ -0,0 +1,9 @@
+import { ETAGetterRepository } from "./ETAGetterRepository";
+
+export interface SelfUpdatingETARepository extends ETAGetterRepository {
+  /**
+   * Attach a event listener to the shuttle repository, listening to
+   * shuttle updates
+   */
+  startListeningForUpdates(): void;
+}