Why add traffic-separated mass transit? A quick cost analysis.
I will ignore all of the other wonderful benefits of traffic-separated transit for this post, and just talk about dollars (using very rough, estimated numbers).
Let's take my morning commute: the #2, #2X, or #13, depending on which one comes first. There seems to be a total of around 12 busses serving these lines*. The end result is having a bus come 16x an hour during peak times. It takes each of these ~20 minutes to get the 2 miles downtown thanks to traffic. The full route is around 45 minutes.
How many busses (or, more realistically, trains) would it take to run this route at an average of 15 mile per hour, which would only be possible with traffic-separated transit? Well, that's more than double the speed, so that would be half the number of trains. So 6.
You'd still get the same frequency of service, but you'd now have 6 less busses and drivers, less maintenance, fewer busses to clean, etc.
Assuming a driver costs on the order of $100k a year**, this is $600,000 saved each year on this one route without even looking at maintenance of the vehicles.
What will it cost us to convert our system for such savings? The deluxe (grade-seperated, think: monorail, or elevated/tunneled light rail) route may be quite expensive, but at a savings of more than $600k per route may pay back quickly. The cheap route (paint on the road reserving a lane for busses, along with signal priority) may create traffic for drivers, but will surely pay back the day you paint the road.
An added cost benefit is that as soon as travel times are cut in half, ridership will immediately go up. Assuming we go for streetcars or light rail instead of busses (and can therefore fit in more riders per vehicle), then we get added farebox income without any additional cost.
*Correct me if I'm wrong - it's my best guess based on time tables.
**I'm sure the average driver makes much less than this, but factoring in benefits, managing this employee, etc. this may even be low.
update:
[Frank]'s comment made me realize I hadn't stated the point of this post strongly enough: One bus moving at 15mph can carry twice the number of (much happier) people the same bus can carry at 6mph. It simply drives the loop twice. Basically, we're paying a whole lot of bus drivers a whole lot of money to sit in traffic with a lot of unnecessary busses.
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You might want to take your figures out to a back alley and punch them up a bit to see if they change their story, but one thing really stands out- 15 mph is a speed that doesn't need to be separated from our daily life.
In reality, Seattle is not a very big town, and transit that can keep moving, even at a modest speed, can get to a lot of places we want to go in a very reasonable time. The ability to impose mobility by fiat, by improving performance by simply banning car traffic from some roads, could be crucial in meeting an out-of-control energy scenario.
On the flip side, frequency of service can also be critical. The commuter is front-loaded with the time to walk to and from the station, and, usually, the sooner you get on the bus, the sooner you get warm and dry.
With the coming densities it seems likely that 15 minute headways on branch lines that gather into trunks of three or four routes towards the city center would provide very acceptable levels of service and speed- if the buses can average 15-20 mph over the ground.
I've added a note to try and make it clear that I'm using very rough estimates, not any calculated values.
An important note: the 15mph estimate includes stops. The 20 minute figure I've used works out to 6 mph including stops, and represents a day where nothing goes wrong (i.e. based on the schedule). I've spent more than 50 minutes coming home, and my average commute time is closer to 35 minutes on my way home. This is less than 4mph (and the reason I ride my bike when it's not raining).
Interesting thoughts, Matt. But there are a lot of other variables to consider. Do you know for a fact that taking 6 buses off the road would allow you to lay off 6 drivers? I kinda doubt it, since rush hour is an especially driver-heavy time, and many of them are part-time.
Also, what would you do with all the extra people if you got rid of 6 buses? Where would they go? If you're planning on putting them on a train, you're looking at about $150M/mile or more for grade-separated transit (probably more on the hilly, urban route that the #2 and #13 run). It would take you 250 years to pay for a 2-mile line, even if you did get the full $600K/year.
It is weird that it takes so long on a bus to travel such a short distance in this town, but much of that is just the reality of the street grid and the geography.
There are certainly many factors to consider, which is why I tried to boil this down to a very simple analysis. Yes, there are part-time drivers, and routes change back and forth into other routes and a full analysis would require far more data than I have. This being said, I've left off other cost savings such as maintenance.
//Where would they go?// Ah, I think you've missed my point. One bus moving at 15mph can carry twice the number of (much happier) people the same bus can carry at 6mph. It simply drives the loop twice. Basically, we're paying a whole lot of bus drivers a whole lot of money to sit in traffic with a lot of unnecessary busses.
//it would take 250 years// Well, perhaps for the gold standard. If we used streetcars that number drops down to around 30 years (using SLUT numbers). That means that after 30 years of much reduced travel time and much increased capacity, we'll start actually making money from switching. How's that for a good purchase? Of course the full LRT solution would have many other benefits that I'd likely be willing to pay for.
//much of that is just the reality of the street grid and the geography// But most of that reality is because we treat cars as the kings of the road. It's time to realize that there's a better way - even stealing a lane from cars can significantly reduce traffic. How? Because a rush-hour bus replaces the better part of a hundred cars.
Did you also measure the acceleration difference between electric transit and diesel? It can make quite a difference.
I wish! Disclaimer: this post uses only vague knowledge on the part of the poster, and no calculators were harmed in it's creation.
Of course the difference wouldn't be great for this route, as many of the busses are electric trolley busses.