Undercount.

Municipal 311 deduplication. Converts how many people complained into how many problems exist. Toronto 311 open data, 2025.

Concentration

One street corner produces 14.4% of every redundant 311 report in Toronto. It is not a street corner problem. It is an automated submitter.

An aggregate duplicate rate is only meaningful if the duplicates are spread across the city. If a handful of places produce most of them, the rate is a story about those places. This page names them, quantifies them, and records which were excluded from the headline numbers and on what evidence.

Where the redundancy is

13,387
redundant reports, city-wide
unit: requests · source: redundancy_concentration
14.41%
from the single worst place
unit: percent · 1,929 reports
26.06%
from the top 10 places
unit: percent · 3,489 reports
35.24%
from the top 100 places
unit: percent · 4,718 reports
Top 12 (service type, intersection) pairs by redundant reports. “Redundant” means reports closable as duplicates of an earlier one: cluster size minus one, summed.
Service request typeIntersectionWard Redundant reportsClusters
Moving Motor Vehicle Noise BATHURST ST & CANYON AVE York Centre 1,929 19
Staff Service - Complaint - 311 Toronto JOHN ST & KING ST W Spadina-Fort York 726 26
Staff Service - Compliment - 311 Toronto JOHN ST & KING ST W Spadina-Fort York 330 25
Moving Motor Vehicle Noise BATHURST ST & SHEPPARD AVE W York Centre 139 6
Comment - 311 Toronto JOHN ST & KING ST W Spadina-Fort York 122 22
Hydrant-Leaking BIRCHMOUNT RD & SHEPPARD AVE E Scarborough-Agincourt 71 4
Expressway Requires Cleaning F G GARDINER C W & GARDINER X W GARDINER C W Etobicoke-Lakeshore 53 21
Bridge - Graffiti Complaint SOUSA MENDES ST & W TORONTO RAIL PATH TRL Davenport 41 18
Pick up Dead Wildlife BERKELEY ST & RICHMOND ST E Toronto Centre 40 1
Traffic Signal Equipment - Graffiti Complaint BLOOR ST W & ST GEORGE ST University-Rosedale 38 16
Pothole on Expressway F G GARDINER C W & GARDINER X W GARDINER C W Etobicoke-Lakeshore 37 11
Road Pothole / Road Damage MCCOWAN RD & SHEPPARD AVE E Scarborough North 34 12

Units: reports, clusters. Source: query top_redundant_places in sql/10_evidence.sql, over all intersection-located requests in 311 Service Requests 2025.

Artifact 1, Bathurst St, an automated submitter

Location
BATHURST ST & CANYON AVE
Ward
York Centre (06)
Service request type
Moving Motor Vehicle Noise
Largest single cluster
278 reports, 2025-01-01 to 2025-01-15 (14 days)
Reports, full year
1,948
Redundant reports, full year
1,929
Share of all city redundancy
14.4%
Share of its own type, city-wide
84.62%

Why it is an artifact and not a very loud street

Three independent checks. Any one alone would be suggestive; together they are not ambiguous.

a. The reports arrive on a timer. On 2025-01-08, 27 reports landed between 17:29:13 and 17:56, spaced 43 to 46 seconds apart. Across the year, 30.1% of consecutive reports at this corner arrive 30–60 seconds apart, against 14.7% for every other noise report in the city. No group of residents telephones on a metronome.

Share of consecutive reports arriving 30–60 seconds apart, for every (type, intersection) with at least 40 gaps to measure. The whole file, 500,269 rows.
Service request typeIntersection Gaps measured30–60s gaps Share
Moving Motor Vehicle Noise BATHURST ST & SHEPPARD AVE W 144 52 36.10%
Moving Motor Vehicle Noise BATHURST ST & CANYON AVE 1,947 586 30.10%
Traffic Signal Equipment - Graffiti Complaint BLOOR ST W & ST GEORGE ST 53 2 3.80%
Pick up Dead Wildlife BERKELEY ST & RICHMOND ST E 40 1 2.50%
Staff Service - Complaint - 311 Toronto JOHN ST & KING ST W 751 1 0.10%
Expressway Requires Cleaning F G GARDINER C W & GARDINER X W GARDINER C W 73 0 0.00%
Bridge - Graffiti Complaint SOUSA MENDES ST & W TORONTO RAIL PATH TRL 58 0 0.00%
Pothole on Expressway F G GARDINER C W & GARDINER X W GARDINER C W 47 0 0.00%

Unit: percent of consecutive inter-arrival gaps. Source: query submission_regularity. The signature appears at exactly two places in the file and both are Moving Motor Vehicle Noise on Bathurst St. Everywhere else in Toronto is at or below 3.8%.

b. Noise complaints do not normally concentrate. This type puts 92.0% of its volume on five corners. The next most concentrated comparable type, Amplified Sound, also a noise nuisance, manages 10.7% across 239 intersections.

Share of a service type's located requests landing on its five busiest intersections. Types with at least 250 located requests.
Service request type Located requestsDistinct intersections Top 5 requestsTop 5 share
Staff Service - Complaint - 311 Toronto 752 1 752 100.00%
Staff Service - Compliment - 311 Toronto 355 1 355 100.00%
Moving Motor Vehicle Noise 2,302 154 2,117 92.00%
Hydrant-Leaking 250 138 91 36.40%
Pothole on Expressway 281 120 92 32.70%
Expressway Requires Cleaning 480 167 148 30.80%
Public Spaces Complaint 529 175 138 26.10%
Traffic Signal Equipment - Graffiti Complaint 585 226 150 25.60%
Road - Graffiti Complaint 435 179 109 25.10%
Bridge - Graffiti Complaint 387 199 92 23.80%
Automated Speed Enforcement (ASE ) Camera Vandalism or Damage 388 203 49 12.60%
Dog Off-Leash in a City Park 287 181 34 11.80%

Units: requests, intersections, percent. Source: query type_concentration.

c. The daily shape does not match the annual shape. Across the year the reports look like a genuine nuisance, weekend-weighted (Saturday 553, Sunday 370, weekdays 172–264) and peaking 16:00–21:00. But inside the 278-report January cluster the pattern is flat and slightly weekday-heavy (weekday mean 19.4, weekend mean 16.3). A real noise nuisance is bursty and weekend-weighted at both scales. This one is only weekend-weighted in aggregate, which is what you get when a submitter runs more often on some days than others.

Disposition. Excluded from the headline duplicate rate and from the seeded demo data. A scripted submitter's output is not a near-duplicate example to learn from; it is a bug. Note the direction of the correction: excluding it makes every headline number in this project smaller.

Artifact 2, the 311 contact centre at John & King

Location
JOHN ST & KING ST W
What is there
Metro Hall, the 311 Toronto contact centre
Service request types
Staff Service, Complaint / Compliment, 311 Toronto; Comment, 311 Toronto
Rows
1,251
Share geocoded to that one corner
100%
Redundant reports contributed
1,178

Why excluded. These records are feedback about the 311 service itself, a complaint about a call handler, a compliment, a general comment. They are geocoded to the building that received them, not to the location of any condition. There is nothing at John & King for a crew to repair. One of these types shows a 100% duplicate rate, which is not a finding about Toronto's streets; it is 752 pieces of feedback filed at one address.

When the exclusion was decided. Before observing its effect on any result. The criterion is what the records are, service feedback, not field conditions, established by reading the type names and confirming that 100% of them sit at the contact centre's own address. The effect was measured afterwards and is reported below whether it helped or not. It made the headline number smaller.

Effect of both exclusions on the headline

The duplicate rate at each stage of exclusion. Nothing is hidden: the as-published number is shown first and remains the number of record for the file as distributed.
Scope Requests examinedClusters Duplicate rateRedundant reports Redundancy
field conditions only (311-feedback types removed) 76,582 64,365 24.81% 12,217 15.95%
field conditions, automated Bathurst St submitter also removed 74,489 64,340 22.70% 10,149 13.62%

Units: requests, clusters, percent. Source: query sensitivity_field_only in sql/10_evidence.sql. As published, before any exclusion, the rate is 26.02% on 77,833 examined requests (query dupe_rate_intersection).

What survives

After both exclusions, 13,387 redundant reports becomes 10,149 across 64,340 clusters, and the largest remaining concentration is well under 1% of the total. That residual is the real, unglamorous duplicate signal: potholes reported by four neighbours, one dead raccoon called in three times, a traffic signal out that six drivers noticed. It is worth deduplicating. It just does not reorder a ward ranking.