The lining around the sides of tram tracks in Croydon town centre appears to be melting in the heat, on what is the hottest day of the year so far.
Pictures show how the black substance on the side of the tracks has gathered, and moved away from the tracks.
The Advertiser witnessed how a small bit of lining used around the edge of one bit of track appears to be softening in today’s sweltering temperatures.
Transport for London (TfL), which owns the tram network, has said a “flexible sealant” has “softened in the hot weather”.
Sand has been put on the tracks at West Croydon and the lining is soft underfoot.
Today is the hottest June day in Croydon since 2005 with temperatures exceeding 31 degrees Celsius this afternoon, local weather expert Ian Currie said.
Sarah Beth, 31, noticed the problem at Lebanon Road and East Croydon and said it worsened as trams drove over it.
Sarah, who lives near the Sandilands tram stop, said: “At Lebanon Road it looked like it is completely stripped and as trams pass over it it comes up even more.
“It looks like it’s happened today as it wasn’t like that yesterday.
Bus tyres are leaving imprints in the lining as they drive over it.
TFL said the sealant melting would not have an impact on the safe operation of the trams.