This is the scene close to Elstree & Borehamwood railway station where flooding has caused services to grind to a halt.
Thameslink trains at the station are disrupted, as are services on the Great Northern Route between Stevenage and Hertford North.
Workers from Network Rail are on site trying to pump the water away from the tracks after bad weather overnight.
A statement on First Capital Connect's website said: "Today's bad weather and flooding is causing some disruption to services on the Great Northern and Thameslink Routes. Network Rail has introduced emergency speed restrictions across part of the network, which means that your journey may take longer than usual.
"Services are disrupted from Stevenage to Hertford North on the Great Northern Route, and at Elstree & Borehamwood on the Thameslink Route.
"Northbound services are also affected by overhead wire problems between Alexandra Palace and New Barnet. Network Rail are working to fix the problem as soon as possible.
"Please check travel details before your journey and allow extra time to complete your journey today."