Starting Line Bottleneck Analysis Post COVID-19

While there are many considerations about how to hold a race in the new normal of Coronavirus and 6 Foot spacing, one of the most prominent bottlenecks is the starting line. While there are many other complicating factors like bib pickup and finish line clearing and course design including width, combined start/finish lines, out and back courses, etc., this blog will focus on the start line to keep things somewhat simple.

This Popular Mechanics article provides the math for social distancing at the LA Marathon, estimating how the 44 foot wide start line for 20,000 participants with 6 feet of social distancing would work. They would be able to have 7 rows of runners with 6 feet of space – which, given their estimated number of participants, results in 2,846 rows of people with 17,070 feet of 6-foot buffers. That’s a starting line that is 3.77 miles long! Assuming the person in the last row averages 15 minutes per mile, they get to the start line about an hour after the gun goes off, not allowing for lag time as runners naturally space out. And gets closer to 30 miles in for their marathon…

Past Examples

There are many examples of wave starts where there is space required between participants. A normal starting line of 15 feet wide for the Scott Coffee race can get about 1,000 people started in about 2-3 minutes. That will not happen if your race is trying to keep a 6 foot spacing.

Obstacle course races have 100-250 people per wave every 10-15 minutes implying a per hour thruput of about 500 – 1,000 people per hour.

Stair climbing events typically have spacing of 5-15 seconds according to Staci Siconalfi-Lymperopoulos of Compuscore. That implies a thruput of 240 – 720 per hour.

Eric Arndt of Its Race Time was kind enough to share some past data on participants per foot fo start line under normal conditions. This data represents the most common start lines they deploy.  Street (17ft), Running Trail (8.5ft) and Narrow (6ft). The data is pulled from the first block of time beginning from gun. This is important because the density tends to drop, as the speed of the runners decrease of course.

A Start Line Model with Social Distancing

Every start line is different, but here is a model that you can use to help you estimate how many participants you can handle. Let’s assume a 12 foot wide start line, so you can have three people on the start line. Then, let’s imagine drawing lines every 6 feet, where 3 people could stand on each line:

If you were able to put 3 people per line, you would need 34 lines to hold 100 runners, which would stretch the distance between the start line and the last line to 201 feet. In reality, not everyone is going to fill in each line, so let’s make the math a bit simpler and say we have 50 lines. That works out to be 300 feet, and the length of a football field (or a bit longer than the straight away on a track).

So, let’s say the starting area is filled with 100 runners. Let’s assume it takes about 2 seconds for each line to respond to the line directly in front of them starting up (people will be cautious coming out of isolation for a while – maybe it improves to 1 second over time). That means it takes 100 seconds for the last line to start. Let’s assume that last line starts slowly – about the pace of a walker at 3 miles per hour, or 4.4 feet/second. They cover the 300 feet to the real start in about 68 seconds. So it takes 3 minutes to clear the starting area.

Then you have the challenge of getting the next 100 people into place so the next wave can start. That might take 5-10 minutes depending on organization. Again, in the early days, it will likely take longer. Once participants get used to the new normal and better procedures are developed it will probably be on the longer side. For those who want to plug in their own numbers, the rough algebra looks like:

Runners per hour = (# of Runners / Wave) * (60 Minutes/Hour) / ((Minutes to Start Wave) + (Minutes to Fill Start Area for Next Wave))

Using the above example:

Runners per hour = (100 Runners/wave) * (60 Minutes/Hour) / ((3 Minutes/wave) + (10 Minutes/wave)) = 100 * 60 / 13 = 461 Runners per hour.

The logistics might be easier to say every 15 minutes, which is more simply understood to be 400 participants per hour. If you send a 100 person wave each 10 minutes, it is 600 participants per hour.

Again, that is with a football field of length to the start area, and a 12 foot / 3 person wide start. Use the formula above to plug in your own numbers and assumptions.

Staging Area

Of course, you need room to stage all of your participants. We will cover that more in other blogs, but at a very high level, you need a full football field to hold 1,000 people.

Again, this assumes a fair amount of order and space optimization of a bit more than 6 feet per person square.

A football field is 300 feet long and 160 feet wide. That is 48,000 square feet of space.

If you use a more generous allocation for your staging/waiting area, then you could assume that people will want 10 feet between each person. That would be a grid of 16 people X 30 people – or 480 people would fit comfortably in a football field – about 100 square feet per person.

What Does This Mean for Your Race?

Every race is different. Different courses, different starting area configurations, different staging area configurations, different types of participants, different timing options, etc. The above models are really meant as a starting point to help you get planning for a safe event. Hopefully this helps you understand how to limit the number of participants in your event, and plan volunteers, timers, race course closures, etc.

We expect the numbers of runners per hour to increase over time as participants get used to new processes, and race directors and timers get better. Obviously wide spread, fast and inexpensive testing is a big key to making our way back to the good old days. Of course, that might take a while.

In the mean time, we expect smaller races to open up sooner and larger races to have challenges and wait for larger sports arenas and events to drive acceptance of mass events of 5-10,000+. It will be interesting to see if other large marathons follow the example of the cancellation of the Berlin Marathon (originally scheduled for Sept. 27).

2 thoughts on “Starting Line Bottleneck Analysis Post COVID-19

  • The math (in particular the geometry) of the starting grid diagram can be improved. By staggering every other line 3 feet horizontally you can save approximately a foot between rows (think of offset equilateral triangles with 6 foot sides rather than squares). Not a huge amount, but over the course of multiple rows it adds up.

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