Eurostar, whose trains connect London with mainland Europe, on Tuesday played down fears that passengers could face long delays once post-Brexit scanning checks finally begin this year.
The automated system, mostly paid for by Eurostar at a cost of 10 million euros ($11 million), is set to enter operation in early October following long delays in the wake of Britain's departure from the European Union.
It will record a non-EU national's details and biometric data along with their date of entry and exit, keeping track of overstays and refused entries. Passports will still be stamped under the existing system.
London mayor Sadiq Khan recently warned that the new arrangement would cause "chaos".
HS1 -- which operates high-speed rail tracks between London and the Channel Tunnel that connects England with France -- had also expressed concern about potential massive queues.
But at a London press conference with Eurostar on Tuesday, HS1 said major investment had helped to alleviate such worries.
HS1 and Eurostar have "put a lot of money and time and effort into understanding what this actually means for the passenger journey and trying to curate it and make it as seamless and pleasurable as we possibly can," said Richard Thorp, engineering director at HS1.
Eurostar said it would continue to recommend that passengers arrive at its London terminal, St Pancras International, between an hour and 90 minutes before departure, adding that it plans to increase staff numbers to help with the new system.
Britain formally left the EU in early 2020 following the 2016 Brexit referendum, with its citizens losing the right to freedom of movement in the bloc.
Almost 19 million people last year used the Eurostar -- which connects Britain with Belgium, France, Germany and the Netherlands -- as traveller numbers returned to their pre-pandemic levels.