The method and guide, explained
Definition
The first and last mile
Transit trips rarely begin or end at the network. The first and last mile is the access leg of a trip: the portion between an origin or destination and the stop or station where the transit portion of the trip begins or ends, whether it is walked, cycled, or ridden on a connecting service.
A first/last mile access gap is a place where that leg fails: there is no car-free way to the station, the walk is indirect or hostile, the connecting service is too infrequent or ends too early, among others. Diagnosing these failures (and deciding which to address first) is what this guide is for.
Orientation
What this is
This method diagnoses first/last mile access gaps for a subject (the station area, downtown, campus, or district whose connections are being studied) and prioritizes them according to community objectives. It identifies the places where connection to the subject would most advance those objectives, assesses how those connections fail, and orders the resulting gaps for action.
Each step is paired with a worked Flux walkthrough, but the method itself is tool agnostic: the complete sequence can be carried out with any suitable spatial-analysis tools and datasets.
Four records
What it produces
Connection objectives
The connections the study will prioritize (to areas, trips, people, or places), each tied to a community or service goal and to indicators that show where it is met.
Priority Areas
Areas where demand and priority for connection concentrate: the places that warrant access diagnosis.
Access-gap inventory
A record of each gap’s area, assessment, verdict, evidence, and a note on why the verdict was made, with the class of intervention it implies.
Priority-ordered program
Diagnosed gaps ranked by severity, demand, priority, and distance.
The sequence
Four phases, one chain of evidence
Framing the Study
Define the subject and the catchment that bounds the study.
Identifying Connection Priorities
Identify connection objectives and the indicators that show where they are met, then designate the Priority Areas where those objectives concentrate.
Diagnosing Access Gaps
Run the selected gap assessments on every Priority Area and record a verdict for each.
Sequencing the Program
Rank the diagnosed gaps by severity, demand, priority, and distance, then hand the program to the decisions that follow it.
Method logic
Why this approach
Demand is established before supply is examined
The method first establishes where demand for connection to the subject concentrates and which demand the community has decided to prioritize. Only then does it examine the access supply: the infrastructure, services, and environment that carry the connection. A gap is prioritized demand that the supply fails to serve.
Priorities do not determine the diagnosis
Priority Areas are designated before access conditions are examined, and verdicts are recorded without reference to priority scores. Whether and how a connection fails is judged from its evidence and local knowledge, not from how much the area matters.
Evidence is combined only at sequencing
Priority and diagnosis are recorded separately and meet only when the program is sequenced. Each assessment names the class of intervention a gap implies, and its verdict sets the gap’s severity; demand, priority, and distance then establish the order.
Scope boundary
What it does not do
The methodology does not prescribe a community’s objectives; it takes them as given. It identifies the class of intervention implied by each gap, but it does not cost improvements, test feasibility, or select among alternatives.
That work begins with the priority-ordered program this guide produces.
Reading model
Method and Flux walkthrough
Method
The tool-agnostic procedure: what a step establishes, what it produces, and how it commonly goes wrong. Read these sections alone for the complete methodology.
Flux walkthrough
The same step worked through in Flux, using a single regional rail station example carried through every step. These sections add implementation detail and are optional.
Before you begin
What you’ll need
Flux (or a GIS tool with regional demographic, land-use, and travel data)
A subject area to study
Access and mobility goals