Tuesday, April 10, 2012

Some more from that LRT Evaluation

I was looking for a bit someone was talking about in the evaluation reports of the LRT and I noticed the following:

I did the math sometime ago on the actual buses going up and down Douglas and the numbers did not add up.   I left it at that until today.  

Today I decided to look at their reference source - the Transit Capacity and Quality of Service Manual.   I went to look at Exhibit 1-6 that they took this data from to see the original source material.

 I look through this table and I see that the capacity for buses all depends on what you are doing.   Can you have more than 2,000 passengers per hour on buses?  Yes.   Victoria uses one of the options, which is not listed in the figure above.   Victoria uses skip-stop operation on Douglas downtown.  What this means is that buses do not stop at all bus stops, it is if we have an A and a B set of bus stops.   Some buses only stop at A bus stops and others only at B bus stops.   According to the manual, skip-stop operation can increase capacity three to four fold.  Suddenly the 2,000 person limit above becomes 4,000 to 4,000 because what of what Victoria is already doing - the system here is not as sophisticated as elsewhere.  Skip-stop operation also increases the average speed of the buses.

The average capacity numbers in the manual work on the idea that the average transit bus has a capacity of 55-75 people, which is how the Rapid Transit Project Evaluation seems to have come up with a capacity of 65 passengers per bus.   The reality is that Victoria uses single deck buses with capacity over over 75 and then has double decker buses with a capacity of 100.   The number that should be used for average capacity in Victoria is 85, 20 more than in the report.   Applying the changed bus capacity figure means the 2000 number quoted above should be 2600 and with Skip-stop we get a capacity of 5200 to 7800 passengers by bus on Douglas downtown.  This is very close to the current observed capacity in peak time.

So using the reference source quoted in the evaluation, I can show the math that the capacity of Douglas Street for bus transit is significantly higher than the VRRTP evaluation said it can be.   It also shows that the current observed volumes are mathematically possible - I really love it when a theory can confirm reality and that it confirms I  am capable of reading the bus schedule, something that seems to eluded the writers of the VRRTP Evaluation.

In reading through the companion chapter in the Transit Capacity and Quality of Service Manual related to rail transit, it confirms all my assumptions on the capacity of the LRT - 3500 seems to be roughly the upper limit of potential passengers per hour.   The plan calls for the LRT system to max out at around 3000 passengers per hour.  
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