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Walking will be banned on escalators as part of a trail designed to reduce congestion（拥堵）at some of the country’s busiest stations．
In the first move of its kind，all travelers will be forced to stand on both sides of escalators on the London Underground as part of a plan to increase capacity（容量）at the height of the rush hour．
A six﹣month trial will be introduced at Holborn station from mid﹣April，eliminating the rule of standing on the right and walking on the left．The move，imitating a similar structure in Far Eastern cities such as Hong Kong，is designed to increase the number of people using long escalators at the busiest times．it could be expanded across the Tube network in coming years．
According to London Underground，only 40 percent of travelers walk the full length of long escalators，leaving the majority at the bottom as they wait to get on to the “standing” side．
A three﹣week trial at Holborn last year found that the number of people using escalators at any one time of could be raised by almost a third．Peter McNaught，operations director at London Underground，said：“It may not seem right that you can go quicker by standing still，but our experiments at Holborn have proved that it can be true．This new six﹣month trial will help us find out if we can influence customers to stand on both sides in the long term．”
Holborn has one of the longest sets of escalators on the Underground network at 23.4 high．Tube bosses claim that capacity was limited because so few people wanted to walk up﹣meaning only one side was used at all times．Research has shown that it is more effective use of escalators over 18.5 to ban walking．
The previous trial found that escalators at the station normally carried 2，500 people between 8：30 am and 9：30 am on a typical day，rising to 3，250 during the researching period．
In the new trial，which will be launched from April 18，one of three “up” escalators will be standing only，with a second banning walking at peak times．A third will remain a mix of walking and standing．
（Note：Answering the questions the questions or complete the statements in NO MORE THAN TEN WORDS．）
(1)
What is the existing problem with standing on the right and walking on the left？
(2)
What did last year’s three﹣week trial at Holborn station prove？
(3)
The research suggests that walking should be forbidden on escalators that are at least ____________ in height．
(4)
In the new trail，in addition to one escalator banning walking in rush hours，the other “up” escalators will be used for __________. ．