12 Steps and Entrances

From: City

colophon
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12 STEPS AND ENTRANCES In the chapter on the sensory street I spoke of selling entrances—that is, entrances so inviting that people go in them on impulse. Let me now take up a more basic aspect: entrances that are easy to enter. In most cities the biggest obstacles to pedestrian movement are the entrances to buildings. They are over-engineered, for one thing. Usually they consist of a set of revolving doors, flanked on either side by doors that swing open if you push them hard enough but that are very difficult to push open and that are not supposed to be used anyway . "Please use other door," a sign on them says. Sometimes the sign is mounted on a pedestal just inboard of the door and placed directly in its path, which does seem inconsistent for doors that may have to be used to get out of the place. In any event, it is tough going. The revolving doors do not revolve , really; you revolve them and it often takes many foot-poundsof energy to do it. Some entrances use a set of swinging glass doors, and these are easier to manage. As with revolving doors, however, there is often a second set about twelve feet further inside. All this is necessary , engineers say, to keep cold or hot weather from coming in and, more important, to maintain an air seal so that drafts won't whistle up elevator shafts in a "stack effect." Curiously, most building codes have nothing to say about entrances . You won't even find the word in their indexes. They have a lot Steps and Entrances [175] to say about exits, however, and are very concerned with getting people safely from the inside to the outside. This is proper enough as far as it goes—enough doors for panic egress, doors wide enough, doors that swing in the exit direction. But there is no encouragement for making it easier to go from the outside to the inside, and one provision rules out the best kind of door there is. For the clues to this door, watch a set of swinging doors as the rush hour builds. You may spot an oddity: as the number of people rises to a peak they go through faster and easier. I was first struck with this contradiction when I was studying the morning rush at the main entrance to Place Ville Marie in Montreal, one of the busiest entrances in the world. It has six swinging doors. At eight forty-five the flow was at a rate of six thousand people per hour. There was much congestion, with people queuing up behind one another. Ten minutes later theflow was up to eight thousand people per hour. But now the congestion was less. People were moving through easily and there was little queuing. The explanation lies in the phenomenon of the open door. It is enormously attracting. Given a choice, people will head for the door that is already open, or that is about to be opened by somebody else. Some people are natural door openers. But most are not; often they queue up three and four deep behind an open door rather than strike out on their own. As the crowd swells, more doors will be kept open. The people will be distributing themselves more evenly across the entrance, and finally, at peak, all the doors will be open and the people will be streaming through. The headway between the people going through the doors will be much shorter than is regarded as comfortable. But that is why they move so quickly. They don't give the doors a chance to close. Thought: Why not leave a door open? Or two or three? In New York City it would be against the law. The code says exit doors "shall normally be left in the closed position." Codes in other cities say the same. Then there is the stack effect to worry about, and the heat gain or loss. Fortunately, some building guards have not been properly indoctrinated about these dangers. I've noted a number of occasions when building guards propped a door open, even collapsed the leaves of revolving doors and left them open too. The building still stood. No overpowering drafts whistled through. The elevators continued running. And the buildings were much easier to enter. Even at the peak of the rush hour the capacity of a few open doors is prodigious. A good example...


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