The Roman Map of Britain above shows a sector of Ermine Street for which there was an alternative route. As Ermine Street extended north out of Lincoln and past Scampton an alternative course of Ermine Street curved left and formed a semicircle on a wide heading west of the Humber Estuary. The straight northerly route, traced in red on the map, between Lincoln and York was the shorter, but was not passable over the Humber Estuary during adverse weather conditions. Thus an alternative route was established (see also Roman roads in Britain). This 'alternative' route is detailed in the Antonine Itinerary and linked York (Eboracum), Castleford (Lagecium), Doncaster (Danum), Littleborough (Agelocum) and Lincoln (Lindum). Beginning at the modern Lincolnshire Showground the portion of this route in Lincolnshire is known as Till Bridge Lane, the modern A1500. The route in the Doncaster area, and again north of Castleford, is known as the Roman Ridge or Roman Rigg.