Depending on the setting, there are a lot of numbers to work with. Wynn Claims
7 million visits per year. But really the numbers vary widely (range per year and the weekend/weekday mix)
I took the high end of most estimates and they still look workable.
50k per Sat /Sun = 5.2m per year (50k x 104 Sat/Suns)
15k per Weekday = 3.9m per year (15k x 261 weekdays)
If Wynn actually sustained the numbers I used, he'd have 9.1m visitors per year. So I'm taking something like a "worst case" weekday and a "worst case" weekend. They can't be both right (in a good way).
If the Weekend number and Annual number are right, weekdays end up being just 7k per weekday. So estimate weekdays at 7k to 15k per day. (I'm going to use 12k, below, 'cause the math is easy)
If the Weekday and Annual numbers are right, weekends only need to be 30k to hit the annual projection. So say each weekend day does between 25k and 50k.
The Zakim Bridge processes 16,000 inbound vehicles (carrying
24,000 persons in the AM Rush (6am-10am)
In I-93's rush, 16,000 vehicles make 4,000 vehicles per hour inbound.
Now let's do the Casino:
Take a middle value of 12,000 persons per Casino weekday as if they were commuters
8,000 vehicles
Halve that to consider 2x vehicle occupancy (couples, not SOV commuters)
4,000 vehicles
Split them by arrival direction
1600 from the North
400 from the East (Rt 1/Airport)
400 from the West (Storrow)
1600 from the South & Pike
I'm going to assume there's some kind of peak arrival time, maybe 7pm or 8pm when "dates" and conventioneers arrive. Let's assume that half of a days traffic arrives (or tries to) in this hour:
Vehicle Arrivals at peak hour
800 from the North
200 from the East (Rt 1/Airport)
200 from the West (Storrow)
800 from the South & Pike
That looks bad, but it is also wrong. Probably 50% will get there on the shoulders of the peak hour, so the peak is down to:
Vehicle Arrivals at peak hour
400 from the North
100 from the East (Rt 1/Airport)
100 from the West (Storrow)
400 from the South & Pike
25% of the day's traffic in 1 hour, and 50% in 2 hours, and 2,000 vehicles will be added to a 3,500 space garage in those 2 hours.
Please note: the more you try to make the peak look bad, the whole rest of the day looks absurdly tame. Try to make it look "busy all day" and instead the hourly numbers all settle pretty low.
If the peak is "supposed to be" that peaky it increases the odds that Wynn will nudge it away from Rush Hour, by skewing dinner reservations and showtime starts (staggering them, even).
Assuming half of all traffic arrives in some 2 hour period Here's what the *other* 10 hours of the "waking/non-rush" day look like to handle the other 2000 cars per weekday:
Vehicle Arrivals in a non-peak hour
80 from the North
20 from the East (Rt 1/Airport)
20 from the West (Storrow)
80 from the South & Pike
(200 per hour across 10 hours)
Back to that peak. Would even 400 vehicles/hour kill I-93 (and its ramps, feeders and arterials) that can handle 4,000 per hour? 10% more at rush hour would be devastating (a straw that breaks the camel's back), but we're saying Casino Rush time occurs when 93 congestion has melted away.
You could double or quadruple these numbers per weekend, but then you also have to spread them over 2x to 4x as many peak hours (Matinee? Nightcap?) and you end up back with the same manageable loads.