The methodology ladder

Know who is responsible for every result.

Every Plexus result fits one of four categories: a desktop calculation, a practitioner's judgment, specialist work, or an agency determination. The category tells you who is responsible and what must happen before the item is complete.

Plexus Impact helps professionals prepare and organize environmental-review work; it does not issue determinations, which remain with the lead agency, and is not legal advice.

The four rungs

Each rung is defined by who is responsible for the result.

The rungs do not measure difficulty or confidence. They show whether Plexus, the practitioner, a specialist, or the lead agency is responsible for the item.

Desktop screening

Plexus is answerable for the arithmetic.

What Plexus does: Plexus calculates the result from a published method and the project data on file. The result carries the source table, its edition, the figures used, and the arithmetic.
What it is not: The result is not an impact finding. A practitioner must confirm that the method applies to this project and decide what the result means.
How you recognize it on screen: A number with its unit, method, and test status. It is labelled PLANNING ESTIMATE until the calculation passes its published test standard.

On this rung, for example: Trip generation and the CEQR screening thresholds; Water demand and sewage generation in gallons per day; Solid waste in tons per week; Energy in source BTU per year; School seats, distances to mapped features, lot and zoning readouts.

Planner judgment

You are answerable. Plexus assembles what you need to decide.

What Plexus does: Plexus gathers the relevant regulation, guidance, comparable reviews, and project facts. It shows the sources and identifies any information that is still missing.
What it is not: Plexus does not make the professional judgment or invent missing facts. The practitioner decides the scope, study area, method, and meaning of the available evidence.
How you recognize it on screen: A question, open item, missing project fact, or set of evidence for review. Comparable projects are shown as context, not as a prediction.

On this rung, for example: Which study areas the review should cover, and how wide; Whether a screening result warrants a fuller analysis; What comparable reviews imply for this site; A project fact we do not hold, such as an employee count or a unit mix; Which of the open items must be resolved before filing.

Specialist and fieldwork

A licensed or qualified professional is answerable.

What Plexus does: Plexus identifies the fieldwork or specialist study a review needs, explains why, and says what the finished work should contain. It stays with the review item it answers.
What it is not: Plexus does not perform the study or predict its result. A map cannot delineate a wetland, measure sound, or complete a Phase I ESA.
How you recognize it on screen: A specific request that says what to commission, who should prepare it, and what question it will answer.

On this rung, for example: Wetland delineation and a jurisdictional determination; Phase I ESA, and Phase II sampling if it is indicated; Ambient sound measurements; Peak-hour turning-movement counts, signal timing and lane geometry; Archaeological and architectural resource investigation.

Agency determination

The lead agency is answerable. Never Plexus.

What Plexus does: Plexus organizes the record, tracks the review process, and shows relevant outcomes from comparable reviews as context.
What it is not: Plexus does not predict an agency decision. The lead agency decides significance, segmentation, scope adequacy, and whether to accept a filing.
How you recognize it on screen: The determination is shown only once an agency has made it, and it is attributed to that agency with its date.

On this rung, for example: The determination of significance, negative or positive; Whether an environmental impact statement is required; Scope adequacy, and acceptance of a filing; Lead agency designation itself.

Classify a result

Ask these questions in order.

Start with the first question and stop at the first yes. This places each item on one rung, even when several people contribute to the work.

4
Does a lead agency have to rule on it before it is settled?
Yes. Rung 4. Plexus can organize the record for it and can show what comparable reviews received. It states no expectation about the outcome.
3
Does it need work only a licensed or qualified professional can sign?
Yes. Rung 3. Plexus names the request and holds the result. It does not estimate what the result will be.
2
Does it turn on a judgment, or on a project fact that only your team holds?
Yes. Rung 2. Plexus assembles what it has, states the question, and names what is missing. The judgment is yours, and so are the project facts behind it.
1
Is it arithmetic over a published method and data on file, reproducible by hand?
Yes. Rung 1. Plexus computed it, and it is a planning estimate until the method behind it has cleared a stated bar.

If a result does not make its rung clear, please tell us.

Rung 1, in detail

A calculation is not automatically a validated result.

Plexus can calculate a result when the method and the figures it needs are on file. That alone does not show the result agrees with a study prepared by a professional.

We label every calculated result as a planning estimate until it has been tested against filed studies and met a published standard. We show the standard, sample, result, and limitations for each test.

study types organized

with a calculation Plexus performs

checked against filed studies

that met the bar set beforehand

One of 21 study types has a calculation that met a standard set before testing. That result must be tested again under the current sample-size requirement. All other calculated results are labelled as planning estimates.

The three backtests run so far
Solid waste and sanitation services	Met the standard, on too few cases	Tested against 5 filed studies. The median difference was 6.9%, compared with a standard of 15% set before testing.
Water demand and sanitary flow	Did not meet the bar	Tested against 8 filed studies. The median difference was 17.1%, compared with a standard of 15% set before testing.
Energy demand	Did not meet the bar	Tested against 5 filed studies. The median difference was 65.1%, compared with a standard of 30% set before testing.

Previously passed a five-case check; not yet tested against the current eight-case minimum. The minimum was raised to eight cases on August 27, 2026. The solid waste and sanitation services test predates that change and must be run again before it can meet the current standard.

Not yet compared at all: Traffic, Traffic impact study (level of service), Community facilities, Greenhouse gas emissions, Noise, Open space. These calculations show their methods and the figures they use, but they have not been tested against filed studies.

Saved snapshot generated September 30, 2026. Study list version 2026-08-24. The table below checks for current figures and identifies whether it is showing live data or the snapshot.

The table below shows what Plexus can calculate or organize for each study type. If a calculation did not meet its test standard, the table reports that result.

Plexus currently supports 21 technical study types. 9 include a planning calculation, and 1 of those has met the current test standard. The other 12 are organized as sourced review work rather than calculations.

Calculation available and tested against filed studies (1)

Plexus calculates the result from a published method and the project's own figures. The calculation met its published test standard against filed professional studies.

Study	Source or method	Comparison with filed studies
Solid waste and sanitation services	Source material on file. CEQR Ch. 14, 22 entries, every quote located in the source PDF Manual reconciliation with the published source is pending.	Met the standard, on too few cases. Tested against 5 filed studies. The median difference was 6.9%, compared with a standard of 15% set before testing. Previously passed a five-case check; not yet tested against the current eight-case minimum.

Planning calculation available (8)

Plexus calculates the result from published methods and rates. The result carries the figures it used and their sources, but testing against filed studies is not complete.

Study	Source or method	Comparison with filed studies
Traffic trip generation and the Ch. 16 screen	Source material on file. CEQR Ch. 16, 270 entries, every quote located in the source PDF Manual reconciliation with the published source is pending.	Comparison with filed studies is pending.
Traffic impact study (level of service)	Source material on file. hcm_los.py, los_screen.py	Comparison with filed studies is pending. Specialist or field input: Peak-hour turning-movement counts, Signal timing and lane geometry.
Community facilities schools	Source material on file. CEQR Ch. 6, 26 entries, every quote located in the source PDF Manual reconciliation with the published source is pending.	Comparison with filed studies is pending.
Water demand and sanitary flow	Source material on file. CEQR Ch. 13, 13 entries, every quote located in the source PDF Manual reconciliation with the published source is pending.	Did not meet the standard. Tested against 8 filed studies. The median difference was 17.1%, compared with a standard of 15%.
Energy demand	Source material on file. CEQR Ch. 15, 5 entries, every quote located in the source PDF Manual reconciliation with the published source is pending.	Did not meet the standard. Tested against 5 filed studies. The median difference was 65.1%, compared with a standard of 30%.
Greenhouse gas emissions	Source material on file. CEQR Ch. 18, 28 entries, every quote located in the source PDF Manual reconciliation with the published source is pending.	Comparison with filed studies is pending.
Noise CEQR screening and attenuation	Source material on file. CEQR Ch. 19, 20 entries, every quote located in the source PDF Manual reconciliation with the published source is pending.	Comparison with filed studies is pending. Specialist or field input: Ambient sound measurements.
Open space	Source material on file. CEQR Ch. 7, 32 entries, every quote located in the source PDF Manual reconciliation with the published source is pending.	Comparison with filed studies is pending.

Study work organized and sourced (12)

Plexus identifies the study question, relevant rules or guidance, and material needed. The final column lists any missing information or specialist work.

Study	Source or method	Information or work still needed
Environmental justice	Source material is still needed. Required source: The CP-29 screening steps, and a method for the consideration ECL 8-0113 requires. The State's designated-DAC list is no longer outstanding: `dac.screen` reads it at request time. What is missing is a method, and CEQR Ch.23 s 300 records that DEC's rulemaking implementing 6 NYCRR 617 was not final when the chapter was written, so no published one exists to encode.	Figures still needed: EPA EJScreen indicators
Land use, zoning and public policy	Source material is still needed. Required source: District use and bulk rules as data — NYC Zoning Resolution first, then the municipal codes behind the Part VII campaign	Figures still needed: Use and bulk rules for that district
Shadows	Source material is still needed. Required source: CEQR Ch. 8 shadow screening geometry (tier 1/2/3 screens and the four analysis days)	Figures still needed: Building height, Building footprint
Transit and pedestrians	Source material is still needed. Required source: CEQR Ch. 16 modal split and transit trip assignment factors, encoded as a catalog	Figures still needed: Transit stops, routes and headways
Stormwater and water quality	Source material is still needed. Required source: NYSDEC Stormwater Management Design Manual — water quality volume, runoff reduction, sizing criteria	Figures still needed: Design rainfall depths
Air quality screening	Source material requires verification. The published method will be cited in the workspace after reconciliation with its source catalog.	Figures still needed: Parking spaces, Heating fuel and floor area, Distance to the nearest receptor
Climate and flood resilience	Source material is still needed. Required source: NYS sea level rise projections (6 NYCRR Part 490) and the ClimAID design tables	Figures still needed: Sea level rise projection for the region
Wetlands, habitat and species screening	Source material on file. geodata.py, spatial_analysis.py	Fieldwork still needed: Wetland delineation, Natural Heritage response, and any survey it asks for
Historic and archaeological screening	Source material on file. geodata.py	Figures still needed: Archaeological sensitivity
Hazardous materials screening	Source material on file. geodata.py	Fieldwork still needed: Phase I ESA findings, Phase II sampling results
Socioeconomic conditions and displacement	Source material on file. CEQR Ch. 5, 77 entries, every quote located in the source PDF Manual reconciliation with the published source is pending.	no backtest has been run against real studies from the corpus
Urban design and visual resources	Source material is still needed. Required source: A viewshed method: terrain, the structure's envelope, and the convention for choosing representative viewpoints. CEQR Ch. 10 for the city and NYSDEC Program Policy DEP-00-2 for the State describe what an assessment contains; neither publishes a computation to encode.	Fieldwork still needed: The structure's height and bulk, Panel height, row spacing and screening, for an array, Photographs from agreed viewpoints

Showing a saved snapshot, generated September 30, 2026, while current figures are being checked. Study list version 2026-08-24. The following rows also draw figures from public services queried at the time of a screening rather than from data held here, so those lookups are unconfirmed while this page is showing stored figures: Traffic, Community facilities, Water demand and sanitary flow, Solid waste and sanitation services, Open space, Environmental justice, Shadows, Transit and pedestrians, Stormwater and water quality, Climate and flood resilience, Wetlands, habitat and species screening, Historic and archaeological screening, Hazardous materials screening, Socioeconomic conditions and displacement, Urban design and visual resources.

The measurement record includes the test runs, cases, limitations, and withdrawn results. Read the measurement record.

Rung 4

Plexus does not predict agency determinations.

An earlier version of Plexus used comparable reviews to estimate how an agency might decide. We removed that feature after testing showed that it did not provide a reliable prediction.

Plexus still shows comparable reviews because they can help a practitioner understand the process and investigate relevant issues. It does not turn those outcomes into a prediction. The lead agency makes the determination for the project before it.

Why the record is kept this way

Every result should lead back to its basis.

Each item keeps its project facts, source, and next action. A calculation carries the figures it used, the method, the assumptions, and the result. A practitioner question carries the regulation or guidance behind it. Specialist work carries the request and the finished study. An agency decision carries the filing, the response, and its date.

This lets the team see what changed, what supports a draft, and what remains open. It also lets a reviewer trace any result back to its source.

Scope

Built for New York environmental review.

Plexus is designed for SEQR statewide and CEQR in New York City. It is most useful at the beginning of a project, when the team needs to establish the review path and the work plan, and it continues to hold the record as the project changes.

Something on this page wrong or out of date? Tell us.