How common are border checks on buses and trains Dublin-Belfast (and back)?

I've read stories about buses being stopped on the motorway Dublin-Belfast for immigration checks, and border guards boarding the Dublin-Belfast train for checks.

How often does this actually happen? And is it more common on buses or trains? I assume it is very rare, not least since the motorway was not built with a dedicated sidetrack for vehicles to stop for checks.

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Is there a border check between Dublin and Belfast?

There is no border check, but you are required to have your passport if you not an Irish or UK citizen. There is no border control. You'll know when you're in the South when the speed limit signs change to km/hour ( they use miles/hour in the North) and the road signs are bilingual.

Are there passport checks between Belfast and Dublin?

There are no routine passport controls in operation for Irish and UK citizens travelling between the 2 countries. However, you must show identification to board a ferry or an airplane, and some airlines and sea carriers only accept a passport as valid identification.

Do I need passport from Belfast to Dublin train?

No you won't need a passport going from Dublin to Belfast. The best way to travel IMHO is on the Enterprise Train which leaves from Connolly Station. This really is a lovely train and there is some great scenery on the journey. There is no border/immigration control between North and Southern Ireland.

Do I need a visa to go from Dublin to Belfast?

If you're an EU, EEA or Swiss Citizen travelling to the UK for a short business trip, you may not need to apply for a visa. Under the UK's new points-based immigration system, you can continue to visit the UK without applying for a visa. In most cases you can stay for up to 6 months.

Ireland's Stunning Cross-Border Train - Dublin to Belfast

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Images: Ketut Subiyanto, Blue Bird, Ketut Subiyanto, Ketut Subiyanto