Y Combinator and Singularity University, September 2018

Two campuses, side by side

Both walks were timed, and every piece was photographed: Walker A's in the grabber, Walker B's mostly where they lay. Walker A walked both campuses, so Walker A's pace is the fair comparison: 4.4 pieces a minute at Y Combinator, 4.8 at Singularity University. Cigarette butts were a bigger share at Singularity University: 39% against 34%.

Y Combinator, Mountain View campus

Thursday, Sep 6, 2018 · 1:10 pm to 1:48 pm

240pieces

38.6minutes

4.4a minute, Walker A

Pioneer Way and W Dana Street, two walkers. Walker A picked up 169 pieces; Walker B photographed 71 on one patch, where they lay. Together that is 6.2 pieces a minute. 35% paper, 34% cigarette butts, 26% wrappers and other.

Singularity University

Saturday, Sep 22, 2018 · two loops, 3:28 to 4:42 pm

227pieces

46.6minutes

4.8a minute, Walker A

Gorsky, Girard and Dailey Roads, Walker A alone, in two loops with a 27-minute break. 39% cigarette butts, 32% paper, 23% wrappers and other. One photo, taken before the walk, is in the 227 but not in the pace (226 pieces in 46.6 minutes).

88%

of Y Combinator's cigarette butts (71 of 81) lay in the last 150 m of Pioneer Way, at its south end.

4.4and4.8

pieces a minute for Walker A, the one person on both campuses: Y Combinator, then Singularity University.

69%

less litter per metre of street at Y Combinator than on a Polk Street cleanup day that summer.

What they were

Y Combinator, Sep 6Singularity University, Sep 22

Cigarette butts

8189

Paper

8472

Wrappers and other

6352

Bottles and cans

96

Food and glass

38

Pieces by type. The app had no plastic category in 2018: plastic bottles are filed with bottles and cans, the rest with wrappers and other.

Where the butts were on Pioneer Way

Pieces in each 20 m of the street at Y Combinator, from W Dana Street at the north end (left) to the highway ramp at the south end (right). In the first 200 m, past the buildings at the north end, the litter was mostly paper and wrappers (117 of 132 pieces). 71 of the 81 cigarette butts lay in the last 150 m, at the south end.

71 of 81 cigarette butts in the last 150 m

204060

19

50

36

20

1

3

1

7

5

4

15

54

18

100 m

North end, W Dana StreetSouth end, at the CA-237 ramp

Cigarette buttsEverything else

Our recap recommended a sign, a trash can or a cigarette disposal at the end of Pioneer Way: "There was a fairly high concentration of litter there, and we didn't see a trash can or community cigarette disposal."

What the posts said, checked

Our recap of the Y Combinator walk (blog, June 2019) and our comparison of the two campuses (Medium, November 2019), against the open data.

Post	What it said	The data
Both recaps	Y Combinator: 240 pieces in 38 minutes, 6.32 a minute, on 2 streets (Pioneer Way, W Dana St), on September 6, 2018.	240 pieces by two walkers from 1:10 pm to 1:48 pm on September 6, 2018 (38.6 minutes): 6.32 a minute over 38, on Pioneer Way and W Dana Street. Walker A alone: 4.4 a minute.Matches
Both recaps	Y Combinator: 35% paper, 34% tobacco, 26% other, 4% plastic, 1% food, 0% glass.	35.0% paper, 33.8% cigarette butts, 26.2% other, 3.8% bottles and cans, 0.8% food, 0.4% glass.Matches
Medium, Nov 2019	Singularity University: 226 pieces in 47 minutes, 5 a minute, on 3 streets (Dailey, Girard, Gorsky).	227 pieces by one walker that day. One photo, at 1:41 pm, was taken nearly two hours before the walk; the other 226 lie in two loops of 46.6 minutes, 4.8 a minute (the post rounds to 5).Matches
Medium, Nov 2019	Singularity University: 39% tobacco, 32% paper, 23% other, 3% plastic, 2% food, 1% glass.	39.2% cigarette butts, 31.7% paper, 22.9% other, 2.6% bottles and cans, 2.2% food, 1.3% glass.Matches
Medium, Nov 2019	"While both campuses did great, Singularity University did a little bit better. There were, though, a bit more tobacco pieces on the ground."	Counting everyone on the walk, Singularity University had fewer pieces a minute (4.8 by one walker, against 6.2 by two at Y Combinator) and a bigger share of cigarette butts (39% against 34%). But Walker A, on both campuses, found more a minute at Singularity University: 4.8 against 4.4.Partly
Blog, Jun 2019	The Y Combinator campus had 71% less litter per foot than Polk Street.	240 pieces on about 359 m of street is 0.67 a metre. Polk Street's four blocks (about 419 m) averaged 892 pieces a cleanup day in the pilot's first month, 2.13 a metre: 69% less.Close
Medium, Nov 2019	Singularity University: "We saw plenty of cigarette dispensers!"	Not in the data: the app recorded litter, not bins. Butts were still a bigger share there (39%, 89 butts) than at Y Combinator (34%, 81 butts).Open
Both recaps	20% less tobacco and more paper and candy wrappers (13% at Y Combinator, 7% at Singularity University) than the San Francisco average.	Not checkable: the posts do not say which San Francisco figures they used. On Polk Street that first month, 59% of pieces were cigarette butts, against 34% and 39% here.Open
Blog, Jun 2019	10 pieces of litter in the lecture hall.	Not told apart: every record lies along Pioneer Way and W Dana Street (the file names 20 at the south end after the CA-237 ramp), and a phone's location cannot tell a hall from the street outside it.Open

Watch both walks

The story first, then both campuses on the map. The camera glides down to Y Combinator and follows Walker A along Pioneer Way, leans over to Walker B's patch, then flies 2.6 km north to Singularity University and follows the second walk. Both walks play at the same speed, about 42 seconds of replay for every hour on the street (0.7 s a minute), so the two can be compared by eye. Each dot is a piece of litter and turns grey a few minutes later; a live screen in the corner shows the photos as they were taken. At the end, each campus's whole walk appears in a circle beside it, at one scale.

Press play for both walks, 83 seconds. It ends with the two campuses side by side and photos from the walks.

Open the map full screen

Who walked

Two walkersWalks traced from each walker's photos in order

Walker Aboth campuses · 396 pieces (169 at Y Combinator, 227 at Singularity University), most in the grabber

Walker BY Combinator · 71 pieces on one patch in under 5 minutes, photographed where they lay

Two ways of working

Walker A photographed each piece in the grabber before it went in the bag, which is why most photos below look alike: an orange claw and one piece of litter. Walker B photographed most pieces where they lay, without picking them up (45 of 46 records). Routes were not recorded in 2018, so the walks in the replay are traced from the photos in time order.

From the walks

A few of the 416 photos, checked one by one at full size. Photos with people, shadows of people, shoes, cars, brand names or writing are not shown.

Wrapper or other where it lay, Y Combinator campus — Where it lay · YC

Wrapper or other in the grabber, Singularity University — Other litter · SU

Cigarette butt in the grabber, Y Combinator campus — Butt · YC

Paper in the grabber, Y Combinator campus — Paper · YC

Bottle or can in the grabber, Singularity University — Bottle or can · SU

Cigarette butt in the grabber, Singularity University — Butt · SU

About these numbers

416 records, 467 pieces (a photo can hold more than one piece): 201 records and 240 pieces at Y Combinator on September 6, 215 records and 227 pieces at Singularity University on September 22, 2018. The open-data file names the whole set "Y Combinator Startup School, Mountain View CA (Sep 2018)"; our November 2019 post names the second campus.
Minutes run from each walk's first photo to its last: 38.6 at Y Combinator and 46.6 at Singularity University, 85.2 in all. At Singularity University the 27-minute break between the two loops is left out, and one photo at 1:41 pm that day, nearly two hours before the walk, counts in the totals (227) but not in the minutes or the pace.
Pieces a minute: the posts' 6.32 and 5 count everyone on the walk. Walker A's pace counts only Walker A's pieces over Walker A's own minutes: 169 in 38.6 at Y Combinator (4.4), and 226 in 46.6 at Singularity University (4.8), where the 1:41 pm photo is left out because it was taken before the walk.
Walker B photographed most pieces where they lay (45 of 46 records are not marked picked up); they count as pieces of litter here, as they did in the recap's 240.
Metres along Pioneer Way are measured from the corner at the CA-237 ramp, along a line drawn down the street, with each record placed on its nearest point. The butts' stretch measures 146 m, shown as 150 m. The file names 20 records at that corner after the ramp; they are counted with Pioneer Way.
Street length at Y Combinator, for the Polk Street comparison, is the stretch of Pioneer Way between the northmost and southmost records plus the stretch of W Dana Street, about 359 m. Polk Street's first month runs from August 11 to September 10, 2018, as in the Polk Street post.
Street names are the ones in the open-data file. The map tiles spell Gorsky Road as Gorsey Road, and our November 2019 post spelled it Grosky Rd.
No tents, needles or human waste were recorded on either walk.
The records are open data: RubbishOpenData, events-2018-2026.csv (CC BY 4.0). No names, accounts or photos; locations to about 11 m.
The 51 photos on the replay's live screen and the ones on this page were checked one by one at full size, cropped below the app's label, and carry no location data.

Two startup campuses, 16 days apart: 240 pieces of litter around Y Combinator, 227 at Singularity University