Thursday, November 10, 2011

Vancouver: the almost perfect grid

A grid pattern of arterial streets covers almost all of Vancouver. Most of the time, parallel major streets are spaced about every 800-1000m apart, and since a comfortable walking distance is about half that, this spacing is perfect for efficient transit.
But what's really great about Vancouver from a transit perspective is the position of its major destinations.  They're positioned in a way that solves another transit planning problem: anchoring.
If a transit line is operating through an area of uniform density, about 50% of its capacity goes to waste. That's because the vehicle will leave the end of the line empty, fill only gradually with passengers, and reach its maximum load at the midpoint of the line.  After that, more people get off than get on, and as you near the far end of the line, the vehicle is nearly empty again.  If you plot the load of the vehicle against the position on the line, you get a bell curve:  zero at the ends of the line, and at its maximum level right in the middle.  If you scale your capacity to the maximum level, you end up with a lot of wasted capacity near the ends of the line, and no way to make use of that capacity.
So transit planners are always looking to anchor their lines.  Anchoring means designing a line so that it ends at a major destination, so that there will be lots of people on the vehicle all the way to the end of the line.  A line with strong anchors at each end will have more uniform high ridership over the whole length of the line, and a much more efficient use of capacity overall.

A street in Vancouver, by blog_bleistift  

A street in Vancouver, by abcde.  

more about Vancouver:

Metro Vancouver Walkability Index

Light Rail, Primary Arterial Transport

Vancouver Master Plan Project

Top 20 Urban Planning Successes of All Time

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