Engineering work is taking place between Harpenden and Mill Hill Broadway, closing some lines.
Until 09:00, buses will replace trains between Harpenden and London St Pancras International.
Trains will run between Bedford and Harpenden.
Check before you travel:
You can plan your journey using the National Rail Enquiries Journey Planner
Replacement Bus Travel Advice:
For helpful advice if you need to travel on a rail replacement service, including accessibility and bicycle information, please use this page.
You can find the location of your replacement bus by checking station signs or by searching for your station on our station information pages.
Please be advised that, on occasion, replacement vehicles may be busier than usual, and you should allow extra time for your journey.