We urban dwellers know we have a big problem every time we try to get to work. For what seems like hours we become zero efficiency machines with the many horses under our hoods jumping up and down going nowhere. Well maybe not ZERO efficiency..after all we are making
some impact...we are obstructing others while spewing emissions from our tailpipes. We are taking up what could otherwise be productive space. We are depleting the world's supply of oil. We are empowering hostile governments...
It's easy to blame the cars......but let's consider, for a moment, another culprit. The roads.
One often overlooked point is that it’s not just that there are too many cars, but rather there are too few roads. While this may seem to be obvious and counter-productive, it raises a couple of important points. First of all, there is traffic because it is too difficult to add lanes in a timely manner. It is too expensive. There may be insufficient space. Now let’s think outside the box and be the three year old who just keeps asking, “why?”
“Well, Junior,” you say, “you need at least ten feet all along the way to add and extra lane..”
“Why?”
“Because it needs to be big enough for cars and even big trucks.”
“Why?”
O.K. now I’m even annoying myself. The point is that we forget that we have a road system designed for big heavy trucks, not the 1.2 person average occupancy of an average car. If you designed roads for commuters in gas sippers only, the lanes could be narrow, the asphalt thin, etc. More lanes, more throughput, faster construction, less money.
One of my main gripes with previous PRT designs is that they seem to forget this lesson. PRT needs to go everywhere a car can go without encountering the “we can’t afford more lanes” problem. It needs to be cheap with a capital C. It must not try to compete with other forms of mass transit between, say two points with only one or two stops in between. That is the realm of trains, or trolleys or buses. PRT should supplement these means by going to where ridership is insufficient to justify larger vehicles. A prime example of where PRT would seem to be less than a great choice is the only active (to my knowledge) program out there, the system to serve Heathrow Airport in London. If you already have people aggregated, and you are transporting them to a single destination, why use PRT?
P.S. Perhaps I shouldn’t use this as an example. In all fairness I haven’t really studied the specifics of that project. Perhaps there are enough terminals on one end and a massive enough parking lot on the other to justify personalized routing. I really don’t know..The point is that PRT needs an extensive network, not just a circular route. That means cheap track, as opposed to the huge cost of expanding truck capable roadways.
