Tuesday, November 27, 2012

Average Capacity Utilization of Port Mann and Massey Tunnel

On yesterday's post, I made the point that transit has better capacity utilization than the current Port Mann Bridge which is about to double in size and the George Massey Tunnel which now “needs” to be replaced. TransLink transit had a capacity utilization of 88%, the Port Mann Bridge of 51%, and the Massey Tunnel of 47% in 2011. Of course a road is a fixed capacity facility, unlike transit which is flexible and able to efficiently respond to demand. I prepared some graphs that show the average annually traffic volume on the George Massey Tunnel and Port Mann Bridge by time-of-day. Even at their peak of utilization (86.6% for the Port Mann and 84.6% for the Massey Tunnel,) transit is still more efficient than the Port Mann Bridge and George Massey Tunnel.

George Massey Tunnel Average Annual Traffic Volume by Time of Day, 2011. Click graph to enlarge.

Port Mann Bridge Average Annual Traffic Volume by Time of Day, 2011. Click graph to enlarge.

We really have a double standard when it comes to our transportation system. We demand a gold-level of efficiency of our transit system, but not of our road network. Our current highway system is designed based on handling the maximum conceivable volume of traffic going a single-direction for a few hours a day. It really is insane. Highways consume a huge amount of land and capital, both of which could be used for other productive purposes, so you’d think we’d be more careful with how we managed highways. We should be even more careful when you think of the short and long-term environmental, social, and health consequences resulting from our highway system.

So while our transit system has been deemed "inefficient" by the Province and service must be optimized, the Province is actively engaged in making our road network "less efficient". Funny how that works.

For the charts the maximum capacity is 1800 vehicles per hour, per lane.


Paul Clapham said...

I agree with the message of this post, but you should be careful that you aren't comparing apples to oranges when you talk about "capacity utilization" of the two systems.

Here's a link which I got off Gordon Price's blog the other day:


You can see it mentions "average capacity utilization", and perhaps you're using similar Translink statistics. Now if you scroll down to Route 025 (the bus I ride quite regularly) you'll see that its average capacity utilization is 188%.

Clearly that's something that can't ever be achieved by a highway -- I guess Translink measures it based on the number of passengers versus the number of seats, although you can't tell just from the document I linked to.

Nathan Pachal said...

Yes, the equlivaient of 188% for roads would be queuing. And there is no question that for peak directions, there is over utilization on the road network for a few hours a day.

Blair said...


Once again you are comparing apples to oranges then? Since mathematically you cannot run a system at 188% of capacity and the 100% capacity for the Port Mann (1800 vehicles an hour) is not attainable due to restrictions in the roads leading up to the bridge and not the bridge itself?
Moreover, Translink’s reporting is at best disingenuous and in reality plainly designed to provide numbers that are good for funding? Their decision to report that 100% capacity is "all seats occupied" is simply a ploy to make themselves look better (by elevating their % capacity status). Buses and Skytrain cars are specifically designed with space for standees, this is part of their standard capacity. To suggest that a standee on Skytrain allows the train to run at greater than 100% capacity is of course a joke which allows them to play fast and loose with the statistics and improve their ridership numbers. The capacity of the Skytrain is the maximum number of bodies allowed on it by Transport Canada. Use that number and all-of-a-sudden Translink has to admit that it is running severely under capacity much of the time.
As for your adding the quotes on “needs” to be replaced with regards the tunnel, that is a result of age of the tunnel not capacity or usage. The tunnel, like all other infrastructure, has a lifespan based on engineering limits of the materials used in its construction. The George Massey tunnel was built in 1959 it was built well but like anything built in 1959 it is getting long in the tooth. Its base materials are starting to degrade and eventually it will fail. It needs to be replaced for that reason alone. The question of what to replace it with is where the debate lies.

Anonymous said...

If 100% capacity means vehicles are full of people in seats, or sitting and standing, then the capacity utilization of roads is typically no more than 25%, since cars with seating for 5 or 6 carry an average 1.25 people or less.