1993年5月，上海地铁1号线开通，5个站，从徐家汇到锦江乐园。
那时候我还在上海。开通的时候挺轰动的，周围有人专门去坐，就是为了体验一下，不是为了去哪里。我也坐过，从徐家汇坐到终点，再坐回来，就这样。当时没觉得这是什么了不起的大事，就是一个新鲜玩意儿。
1998年底，我去了加拿大。
离开的时候，地铁还很小
我去加拿大的时候，上海地铁有了1号线和2号线，站不多，主要就是沿着中环以内跑。出门还是靠公共汽车、电车，地铁只是偶尔用一用，不是主要的出行方式。
渥太华没有地铁，那几年我出行全靠开车和公共汽车。偶尔去多伦多、蒙特利尔，才坐得到地铁，也没什么特别的感受。
2006年回到上海，下了飞机，坐机场大巴进城。路上看着窗外，这座城市变了太多，一时不知道从哪里开始重新认识。
回来的时候是另一张图
当时上海地铁已经有好几条线了，线路图密密麻麻，我站在地铁站里看指示牌，有一种奇怪的陌生感——这明明是我从小长大的城市，但这张地下的网是我不认识的。
离开前我熟悉的那些路、那些公交站，和新的地铁网络之间，有一段对应不上的空白。我花了好一阵子，才把地面上的记忆和地下的线路重新拼接起来。
这种感觉很难描述。不是迷路，是两张地图叠在一起，对不齐。
儿子是另一代人
我儿子今年15岁，在上海出生长大，没有在国外长住过。对他来说，地铁从来就在那里，和自来水、电一样，是理所当然的存在。
但他对地铁的兴趣，不只是"用它出行"。从小就喜欢研究线路图：各条线怎么走、哪里换乘、哪条线最长、哪个站几线交汇，都记得一清二楚。每次有新线路开通，他往往比我更早知道时间表。
有一次他跟我说，18号线是全自动无人驾驶，站在车头可以直接看到前方隧道，没有司机，很特别。我问他去坐过吗，他说当然，去了好几次。
我那时候意识到，他对这张网的了解，已经远在我之上了。
两张不同的地图
我小时候的上海，出行靠电车和公共汽车，地铁不存在。1993年1号线开通，我见证了第一条线，但之后的大部分扩张，我都是在加拿大度过的——2号线延伸、3号线、4号线、世博会前后那几条集中开通的线路，我都不在场。
2006年回来，我只能事后补课，把那些年的变化一条线一条线地重新认识。
我儿子从记事起，这张网就已经相当完整了。他没有经历过"地铁从无到有"的过程，只经历过"从有到更多"。他的上海，天然就是一张越来越密的网。
我有时候想，等他将来有一天离开上海，再回来，会不会也有我当年那种感觉——走的时候是一张图，回来是另一张图？
大概会的。这张网还没停下来。
一个数字
截至2025年底，上海轨道交通运营里程已超过900公里，21条线，500多个站。
1993年开通时是5个站。
三十年，我亲眼见过第一条线，然后在它飞速扩张的那些年缺席了，回来的时候已经不认识它了。
我儿子比我更懂这张网。这事我觉得挺好的。
In May 1993, Shanghai Metro Line 1 opened — five stations, from Xujiahui to Jinjiang Park.
I was still living in Shanghai then. There was a buzz around the opening. People went just to ride it, not to go anywhere specific. I did the same — took it from Xujiahui to the end of the line and back. That was it. I didn’t think of it as anything significant. Just a novelty.
At the end of 1998, I left for Canada.
The network was still small when I left
When I went to Canada, Shanghai had Line 1 and Line 2, not many stations, mostly running within the inner ring. Getting around still meant buses and trolleybuses. The metro was something you used occasionally, not the main option.
Ottawa has no metro. For those years I drove or took buses. I’d ride metros occasionally when visiting Toronto or Montreal, but without any particular feeling about them.
I came back to Shanghai in 2006, flew in and took the airport bus into the city. Looking out the window, so much had changed that I didn’t know where to start.
A different map when I returned
By then Shanghai already had several lines. The route map was dense and complicated. Standing in a station looking at the signs, I felt a strange kind of unfamiliarity — this was the city I grew up in, but this underground network was something I didn’t know.
The streets and bus routes I remembered from before I left, and the new metro lines, didn’t quite line up in my head. It took a while to reconnect my surface-level memories with the routes underground.
Hard to describe the feeling. Not being lost exactly — more like two maps laid on top of each other that don’t quite align.
My son is from a different generation
My son is fifteen, born and raised in Shanghai, never lived abroad. For him the metro has always been there, as given as running water or electricity.
But his interest in it goes beyond using it to get places. From when he was young he studied the route maps seriously — which lines go where, where to transfer, which line is longest, how many lines meet at which station. He had it all memorized. Before new lines opened, he usually knew the timetable before I did.
Once he mentioned that Line 18 is fully automated and driverless — you can stand at the very front of the train and look straight into the tunnel ahead, no driver’s cab blocking the view. I asked if he’d tried it. He said of course, several times.
That was when I understood his knowledge of this network had long since overtaken mine.
Two different maps
The Shanghai I grew up in had trolleybuses and regular buses. No metro. I was there for Line 1 opening in 1993, but I was in Canada for most of what came after — the Line 2 extensions, Lines 3 and 4, the cluster of lines that opened around the 2010 World Expo. I wasn’t there for any of it.
Coming back in 2006, I had to catch up after the fact, relearning the city one line at a time.
My son has no memory of Shanghai without a reasonably complete metro. He didn’t experience the network being built from nothing — only from something to more. His Shanghai has always been a grid that keeps getting denser.
I sometimes wonder: when he eventually leaves Shanghai someday, and comes back years later, will he feel what I felt — that the map he left with and the map he returns to are two different things?
Probably. The network isn’t done yet.
One number
By the end of 2025, Shanghai’s rail network had passed 900 kilometers — 21 lines, over 500 stations.
Five stations in 1993.
Thirty years. I saw the first line open, then missed the years when it grew fastest, and came back not recognizing it.
My son knows this network better than I do. I think that’s a good thing.