Note: Transport for London seems to have done a u-turn on its decision to scale back the real-time updates it issues over Twitter. It has removed its original blog post, described and quoted from below, and posted a new one claiming it has no intention of “stepping back from providing the full range of information” it currently provides.

“We are not making any immediate changes to the current range of information we post on Twitter, which means customers will continue to receive real-time travel updates,” Phil Young, TfL’s head of online, said. “Social media platforms are continually changing and we will continue to work in partnership with them to ensure we provide our customers with the information that they need.”

The original story follows, complete with quotes from the now-deleted TfL post.

Twitter’s decision to tamper with the straightforward chronology of its timeline has prompted London’s travel authorities to scale down the way they issue updates to citizens, including disabled passengers.

Transport for London (TfL) and the U.K. capital’s police force have for years sent out regular alerts as soon as they receive information about disruption to transport routes. However, Twitter twtr has started putting a bunch of algorithmically-selected tweets at the top of users’ feeds — tweets that Twitter’s systems thinks individual users will want to see first.

That selection is still in reverse chronological order like the rest of the feed, but the feature throws out the sequence of the overall timeline. It’s opt-in for now, but it will be automatically turned on for people in the coming weeks, leaving it up to them to opt out.

In a Thursday blog post, TfL said Twitter’s changes had “impacted upon our ability to reliably deliver these real-time status updates to our followers.” It explained that the filtering system is likely to bring only the most important updates to the top of people’s feeds.

“Now selected content on Twitter is shown out of sequence, we will reduce the amount of minor alerts and focus on providing up-to-the-minute alerts for major issues,” the post read.

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This means the @TfLTrafficNews account (567,000 followers) will no longer provide real-time traffic disruption information except for major incidents, @TfL BusAlerts (197,000 followers) will no longer tell people about minor bus-service disruptions, and the @TfLAccess feed (17,900 followers) will no longer give wheelchair users and other disabled commuters real-time alerts about problems with escalators and elevators in stations.

TfL’s individual accounts for each Tube line will also scale down their updates, and the account for London’s bike-sharing scheme will no longer tell people about which docking stations are suspended.

The transport authority’s post included a handy list of the various changes Twitter has made over the years, pointing out that even the introduction of basic retweets back in 2009 altered the feed’s pure chronology. TfL also said Twitter’s year-old “while you were away” feature — similar to the new “home timeline” feature in some ways — has actually helped it to get visibility for its most important messages.

For more on Twitter, watch:

However, the post was clear that the latest change means “only our high impact and important updates would be likely to reach customers in a useful and relevant way.”

It remains to be seen whether Twitter’s tweaks will help it get the user growth it craves, but it’s already clear that they are going to make life more annoying for thousands of London commuters.

If anyone’s looking for a case study of the clash between Twitter-the-company-trying-to-please-shareholders and Twitter-the-infrastructure-people-have-been-starting-to-depend-on, here you go.