Kyle, a transportation staff member for the City of Littleton, gave the Planning Commission a detailed briefing on how the city evaluates transportation impacts for new development, using the 700 West Mineral project as a worked example.

The presentation covered the three usual developer submittals — trip generation letters, transportation impact studies (TIS) and conformance letters — how Littleton applies national guidance (Institute of Transportation Engineers trip-generation rates, the Highway Capacity Manual and Synchro software) and how staff translates the Transportation Master Plan (TMP) street types into right-of-way and frontage requirements for sidewalks, bike facilities and turn lanes.

The commission pressed staff on several recurring issues: which street-classification map controls design decisions; when developers must dedicate additional right of way; whether bike lanes should be on-street or on separated multiuse paths; how trip-generation rates treat trips that already use Littleton roads (for example trips currently driving to other Costco locations); and whether the city’s review tools tend to produce larger vehicle capacity improvements that undermine walkability goals.

Why it matters: Decisions about lane widths, turn pockets, mixing zones and right-of-way dedications determine whether corridor upgrades prioritize vehicular capacity or protected facilities for people walking, biking and using low‑velocity vehicles. Commissioners said those choices shape whether Littleton meets goals in its Envision Littleton planning guidance.

Most important points and examples

- Street classifications and right-of-way. Staff described two parallel frameworks: the TMP’s existing functional classification map and a future street-type overlay city engineers use to guide designs. Suburban connectors such as Mineral Avenue and South Park Terrace were described as having typical right-of-way ranges of roughly 80–120 feet; staff said developers may be required to dedicate frontage right-of-way to meet future cross sections (Kyle gave an example of a roughly 22-foot frontage dedication for one parcel).

- 700 West Mineral and overlapping city projects. Staff said the 700 West Mineral TIS accounted for multiple city projects that overlap the study area (Mineral Mobility East, Mineral Station West, a quadrant/quad road, County Line trail and Broadway HSIP safety work). For locations where developer work and city projects overlap, the developer funds design so city crews can fold the work into a single construction contract rather than build the same intersection twice.

- Trip-generation and analysis approach. Kyle explained Littleton uses the ITE Trip Generation manual (11th edition) as the baseline, applies DRCOG regional growth rates for a 20‑year horizon, and models two study years: a near-term buildout year (2–3 years out) and a longer horizon (20+ years). Staff also model “pass-by” and “internal capture” adjustments (for example, multi‑use sites or trips that divert to a new store on an existing corridor). For special tenants with atypical demand (Costco, Portillo’s, Chick‑fil‑A) staff said the city requests retailer‑specific studies.

- Intersection capacity, level of service and warrants. Littleton’s TIS practice uses Highway Capacity Manual procedures and Synchro software to measure delay and queueing; the city’s standard signalized threshold was described as LOS D, roughly 55 seconds of delay at a lane group. Signal and all‑way stop warrants follow MUTCD guidance; staff said there is some discretion for pedestrian‑based signal justification but developer funding for offsite signals generally requires meeting adopted warrants.

- Bike/ped and multimodal tradeoffs. Commissioners repeatedly raised concerns that vehicle‑focused TIS outcomes can drive geometric changes that make corridors less walkable or comfortable for people biking. One commissioner argued that “land uses attract people,” and that analytic approaches treating land use as trip generators reinforce car-first outcomes; Kyle said the city is adding bike and pedestrian sections to TISs but that quantitative multimodal demand tools are not yet nationally standardized. Staff noted the Mineral Mobility East project will install phase‑1 cycle‑track elements this year but that physical protection and maintenance (snow removal, sweeping) remain outstanding operational issues.

- Typical cross sections and lane-width targets. Staff said the city is moving toward 10–11 foot travel lanes and target 10-foot lanes for many contexts to calm speeds and free space for multimodal facilities. The draft cross sections in Littleton’s engineering standards include options for buffered or protected bike facilities; staff emphasized those typical sections are guidance and that the TMP update and the engineering standards (LEDS/LEHI referenced in discussion) will formalize defaults.

- Right-turn pockets and “mixing zones.” Commissioners objected to proposed auxiliary/right‑turn lanes and “mixing zones” where on‑street bike lanes are required to weave around vehicle deceleration pockets. Staff said for 700 West Mineral the developer will construct some auxiliary right‑turn lanes and that the plan includes through bike lanes and separate, if sometimes closely adjacent, turn lanes. Several commissioners urged that mixing zones be avoided and that the city prefer separated multiuse pathways or protected bike facilities where feasible.

- Design guidance and standards cited. Staff listed national and regional standards they use or consult: ITE Trip Generation, Highway Capacity Manual, AASHTO geometric and roadside design guidance, NACTO bike/ped design resources, MUTCD signal warrants, and PROWAG/ADA accessibility guidance. Staff also described the city’s plan to adopt updated engineering standards and a traffic‑calming toolbox for neighborhood requests (raised crosswalks, traffic circles, chicanes, speed cushions, diverters).

Quotes from the meeting

- Kyle, transportation staff: “this presentation is … development review for transportation impacts” (presentation opening).

- Commissioner (unnamed): “land uses attract people” (arguing that treating land uses only as trip generators drives car‑first designs).

- Commissioner (unnamed): “If it takes somebody a couple minutes longer to get to Costco, that’s too bad” (expressing the view that small travel‑time tradeoffs are acceptable to enable safer multimodal streets).

Details commissioners pressed staff to clarify

- Whether the TMP overlay or the existing functional classification map controls development review decisions (staff: both are used; the overlay guides intended future character while traditional classifications remain for pavement and structural decisions).

- How the city accounts for trips that already travel through Littleton to reach retail outside the city (staff: intersection counts capture existing trips; to be conservative the city generally adds new site trips rather than subtracting trips that might shift from other destinations; DRCOG growth rates and known pipeline developments are incorporated in scoping).

- Which improvements the developer must build versus what the city will fund (staff: developers are responsible for frontage and mitigation directly caused by their project; the city will try to fold developer funding into concurrent city capital projects when feasible).

No formal action recorded

There were no motions or votes recorded in the transcript on these topics. The meeting was a study‑session style briefing and discussion; commissioners gave direction and asked staff to bring policy guidance and standards into the forthcoming engineering standards and TMP update.

Clarifying details

- Typical suburban connector ROW range cited in the discussion: about 80–120 feet.

- Example frontage dedication referenced: roughly 22 feet of right-of-way dedication on one frontage for 700 West Mineral.

- Buffer and bike facility targets discussed: 4-foot buffer envisioned to allow a future raised median; 10-foot sidewalks/multiuse paths were described as the developer requirement in parts of the 700 West Mineral site; staff said phase‑1 cycle‑track elements for Mineral Mobility East will be installed this year but without permanent physical protection initially.

- Lane-width guidance: staff said the city is moving toward 10–11 foot travel lanes and target 10 feet where practicable; older streets have 12–14 foot lanes in many locations.

- Analysis tools: staff cited ITE Trip Generation (11th ed.), DRCOG growth rates (20‑year horizon), Highway Capacity Manual, Synchro software, MUTCD signal warrants, AASHTO and NACTO design guides, and PROWAG/ADA public‑right‑of‑way guidance.

Community relevance and next steps

Commissioners urged staff to accelerate completion of city engineering standard cross‑sections and the Transportation Master Plan update so those policy defaults are clearer in project review. Staff said the engineering standards (draft “LEDS/LEHI” cross‑sections referenced in the discussion) will be completed this year and the TIS format will now require bike/ped narrative sections. Staff also said the city is preparing a traffic‑calming toolbox and will present drafts to the Transportation Mobility Board and then to council. Commissioners asked staff to return with clearer, codified guidance on handling mixing zones, auxiliary lanes and minimum multimodal facility defaults so the commission has a consistent policy basis to review future site plans.

Ending

The study‑session ended without formal votes. Commission members and staff agreed the TMP update, finalized engineering standards and the traffic‑calming toolbox are the policy pieces that will determine how future development reviews balance vehicle capacity with protected multimodal infrastructure.