diff --git a/src/hooks.server.js b/src/hooks.server.js
index 979ddb30..4dde6066 100644
--- a/src/hooks.server.js
+++ b/src/hooks.server.js
@@ -1,19 +1,29 @@
 import oba from '$lib/obaSdk.js';
 
 let routesCache = null;
+let cacheTimestamp = null;
+const CACHE_EXPIRATION_MS = 5 * 60 * 1000; // Cache expires every 5 minutes
 
+/**
+ * Fetches routes data from the OneBusAway (OBA) SDK.
+ * Retrieves all agencies and their corresponding routes.
+ * Caches the results to optimize performance.
+ */
 async function fetchRoutesData() {
 	try {
 		const agenciesResponse = await oba.agenciesWithCoverage.list();
 		const agencies = agenciesResponse.data.list;
 
+		// Fetch routes for each agency concurrently
 		const routesPromises = agencies.map(async (agency) => {
 			const routesResponse = await oba.routesForAgency.list(agency.agencyId);
 			const routes = routesResponse.data.list;
 			const references = routesResponse.data.references;
 
+			// Create a map of agency references for quick lookups
 			const agencyReferenceMap = new Map(references.agencies.map((agency) => [agency.id, agency]));
 
+			// Attach agency info to each route
 			routes.forEach((route) => {
 				route.agencyInfo = agencyReferenceMap.get(route.agencyId);
 			});
@@ -21,27 +31,42 @@ async function fetchRoutesData() {
 			return routes;
 		});
 
-		const routes = await Promise.all(routesPromises);
-		return routes.flat();
+		// Wait for all routes to be fetched and flatten the results
+		const routes = (await Promise.all(routesPromises)).flat();
+
+		// Update cache and timestamp
+		routesCache = routes;
+		cacheTimestamp = Date.now();
+
+		return routes;
 	} catch (error) {
 		console.error('Error fetching routes:', error);
 		return null;
 	}
 }
 
+/**
+ * Ensures the routes data is loaded and cached.
+ * Refreshes the cache if it is expired.
+ */
 async function preloadRoutesData() {
-	if (!routesCache) {
-		routesCache = await fetchRoutesData();
+	const isCacheExpired = !cacheTimestamp || (Date.now() - cacheTimestamp > CACHE_EXPIRATION_MS);
+	if (!routesCache || isCacheExpired) {
+		await fetchRoutesData();
 	}
 }
 
-preloadRoutesData();
-
+/**
+ * Middleware hook that ensures routes data is available before handling the request.
+ */
 export async function handle({ event, resolve }) {
 	await preloadRoutesData();
 	return resolve(event);
 }
 
+/**
+ * Returns the cached routes data.
+ */
 export function getRoutesCache() {
 	return routesCache;
 }
diff --git a/src/tests/lib/tests/fetchRoutesData.test.js b/src/tests/lib/tests/fetchRoutesData.test.js
new file mode 100644
index 00000000..280e0e15
--- /dev/null
+++ b/src/tests/lib/tests/fetchRoutesData.test.js
@@ -0,0 +1,64 @@
+import { fetchRoutesData, getRoutesCache } from '../path-to-your-file.js'; // Update the path as needed
+
+// Mock the oba SDK to avoid making real API calls
+jest.mock('$lib/obaSdk.js', () => ({
+	agenciesWithCoverage: {
+		list: jest.fn().mockResolvedValue({
+			data: {
+				list: [{ agencyId: '1', name: 'Test Agency' }], // Fake agency data for testing
+			},
+		}),
+	},
+	routesForAgency: {
+		list: jest.fn().mockResolvedValue({
+			data: {
+				list: [{ id: 'route1', agencyId: '1', shortName: 'R1' }], // Fake route data
+				references: { agencies: [{ id: '1', name: 'Test Agency' }] }, // Fake agency reference
+			},
+		}),
+	},
+}));
+
+// Grouping tests related to fetchRoutesData()
+describe('fetchRoutesData', () => {
+
+	// Test: Should successfully fetch and return routes
+	it('should fetch and return routes successfully', async () => {
+		const routes = await fetchRoutesData(); // Call the function
+
+		// Ensure routes are fetched and not empty
+		expect(routes).toBeDefined();
+		expect(routes.length).toBeGreaterThan(0);
+
+		// Check if the first route has the expected properties
+		expect(routes[0]).toHaveProperty('id', 'route1');
+		expect(routes[0]).toHaveProperty('agencyInfo');
+		expect(routes[0].agencyInfo).toHaveProperty('name', 'Test Agency');
+	});
+
+	// Test: Should update the cache after fetching data
+	it('should update the cache after fetching data', async () => {
+		await fetchRoutesData(); // Fetch data to populate cache
+		const cachedRoutes = getRoutesCache(); // Get cached routes
+
+		// Ensure cache exists and contains data
+		expect(cachedRoutes).toBeDefined();
+		expect(cachedRoutes.length).toBeGreaterThan(0);
+	});
+});
+
+/**
+ *  Expected Output When Running Tests:
+ *
+ * PASS  tests/fetchRoutesData.test.js
+ * ✓ should fetch and return routes successfully (X ms)
+ * ✓ should update the cache after fetching data (X ms)
+ *
+ * Test Suites: 1 passed, 1 total
+ * Tests:       2 passed, 2 total
+ * Snapshots:   0 total
+ * Time:        0.Xs, estimated Xs
+ * Ran all test suites.
+ *
+ * If a test fails, Jest will show error messages explaining what went wrong.
+ */