Opponents of the multi-billion-euro Stuttgart 21 project have been back on the streets of the German city.
They say plans to modernise the city’s railway station by taking it underground are too expensive and unnecessary.
This was the first rally of the new year after attempts at mediation over the Christmas period failed.
There are major political implications. Regional elections are due in March and Chancellor Angela Merkel is campaigning hard. She says the Baden-Wuttemburg ballot will be a referendum on the project.
Recent polls put her CDU party behind an SPD-Green alliance.