The reason I love business world is, you have to reach a level of excellency in digging into details of all the aspects of your business to really be able to deliver a world class product or services. I tend to practice this skill in worlds other than business. Transportation of large cities is one of the area I spent a lot of time thinking. Here is one of my observation.
Smaller Road Blocks Leads to Better Transportation
I have the gut feeling that the smaller the blocks are, the better the transportation is. Examples are Puxi vs Pudong, or Shanghai vs Beijing. Puxi has much more cars than Pudong, and Beijing has much more big roads than Shanghai, but the Puxi is better in transportation than Pudong, and Shanghai is better than Beijing. Why? When I tried to verify this conclusion and to find the reason, I found some insights. One of them is the importance of right lane.
Right Lane is the Most Important Lane in a City
I thought all lanes are created equal – because they are equal in terms of width. But they are not.
I found this because of the Huashan Road construction. The Huashan Road is the road before my office. It is a main road that goes to Xujiahui on the south. There are 5 lanes at the crossroad with Hongqiao Road. One left lane, one left/forward lane, two forward lanes, and one right lane. The traffic is heavy but for many years, it went on well.
All of a sudden, one day, the whole Huashan Road is blocked. The long queue of cars line from Hong Qiao Road to Guangyuan Road (that is about 1 km long), and extends to Huahai Road (about 1.5 km long). Cars are jammed there, all the day time. From my window, I can see the long line, and hear continous horn from impatient drivers. If you thinking about 2KM queue, and there are 4-5 lanes on the road, you can imagine how many cars are impacted daily. Even buses detoured from this section of road.
What happened? Is there a big change?
Nothing except they closed a right lane at Huahsan Road and Hongqiao Road, and merge it into the straight lane, becaues of the Xujiahui Metro Station construction at Grand Gateway.
Right Lane Multiplied by Time
It is a shocking discovering for me. Before, I thought a right lane = 1/5 of the traffic. It turned out to be the wrong assumption. The key characteristic of right lane is, cars are allowed to turn right ALL the time – at greent light and red light. Cars at forward and left lane have to wait for red light to really “use” the lane to move. What is the percentage of time they can see green light?
At a crossroad of equally important two roads, if there is no seperate left turn light, each side can only use 1/2 of the time. However, that is the whole story. Since the left turn and forward traffic needs to wait for each other, the lane actually is used 1/4 of all the time (assuming left turn and forward are of the same traffic). If there is seperate left turn light, the forward is actually 1/4 of all the time.
Meanwhile, no matter what time it is, the right lane is always available. In a crossroad like Huashan Road and Hong Qiao Road, the utilization of right lane is almost 100% during day time (unlike most other crossroads). The conclusion is, a right lane can archive traffic 4 times as a left or forward lane under full utilization senario.
If the right lane is combined into the forward lane, right lane cars have to wait for the 1/4 of the green light, effectively decreased the output of the road – 3/4 of the traffic capacity is cut.
That is the secret why reducing 1/5 of the lanes causing the capacity to drop to almost half. If you take the capacity of an always green light road to be 1, previously, it was 2 (1 + 1/4 * 4), and now it is 1.25 (1/4 * 5), a 35% decrease.
This translate to the long queue of roads.
Right Lanes and Road Grid
When there are more smaller roads and smaller road grid, the key is, there are much more right lanes than big road system. Like highways, although there are many forward lanes, right lane per km is much less than smaller road system. If it makes sense for expressways to build large road system, it does not apply to cities like Beijng and Shanghai.
With right lanes, the road utilization is increased, because cars can choose to make right turn if they can, and causing less cars on the forward lanes. Meanwhile, right lane cars fills into the empty road when there is red light at the crossing road. In a road grid of many right lanes, the ratio of cars and road area is much higher (higher utlization), and causing a more efficent road system.
P.S. I enjoys learning insights of things like this a lot, just the same way as I run my business. Many people can do the same thing, but only few people really know what they are doing. The excellence of understanding is what I am chasing after.
P.S. 2. It also shows the power of convinience and the meaning of keep doing for a long time. Many things looked alike, if you don’t take the accumulation of time into account, but it is the time factor that makes something so unique. Like business, many companies look alike, but only very few of them can focus on what they determined to focus on, and keep doing it for a long time. That is huge difference.