West Midlands Fire Service was called to Lower Horseley Fields at 8.02am. A spokesperson for the service said it received several phone calls from members of the public. Crews from Wolverhampton, Fallings Park, Bilston, Willenhall and Wednesbury have been sent to the scene.
A statement said: "This morning at 8am we were called to reports of a caravan on fire beneath an archway of a bridge off Lower Horsley Fields, Wolverhampton. The incident involves a caravan and a large quantity of rubbish well alight beneath the bridge archway.
"Due to smoke affecting the rail line, which runs over the bridge above the incident, a stoppage of rail travel has been requested. This will affect rail travel through this area and result in delays or cancellations of nearby rail services. Please follow Transport for West Midlands for rail travel updates.
"Lower Horseley Fields is also closed in both directions to allow safe working for our crews. No casualties are reported at this time."
Passengers on passing trains reported seeing black smoke billowing out with the railway line between Wolverhampton and Birmingham closed for more than two hours. Train services resumed at around 10.15am.
West Midlands Police, British Transport Police and West Midlands Ambulance are all in attendance.
The blaze is in the same road as a massive factory fire last December, which saw a string of businesses engulfed. That fire took three days of round-the-clock work to put out, with investigators from West Midlands Fire Service and West Midlands Police treating it as arson.
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