Scottsdale analysis finds KSI crashes concentrated in South/Old Town; ped/bike crashes overrepresented at intersections and at night

Scottsdale transportation staff and outside consultants presented a data-driven overview of traffic crashes and emerging safety priorities to the Transportation Commission on April 17, 2025, saying the city’s crash record from 2019–2023 shows concentrated risk in South Scottsdale and Old Town.

Dr. Russo, a researcher working with the project team from Northern Arizona University, said the analysis combines two sources of police-reported crash data and covers the most recent five years: “the crash data that we’re using in this analysis is from the most recent 5 years, 2019 through 2023,” he said. He and T.Y. Lin consultant Ryan (senior transportation planner, T.Y. Lin) walked commissioners through totals, severities and where crashes cluster.

The consultants said the combined dataset contains roughly 18,000 vehicle-only crashes plus about 700 pedestrian and bicycle crashes, for just under 19,000 total crashes and roughly 500 suspected fatal or serious injury crashes (KSI) across the five years. Pedestrian and bicycle crashes accounted for a much higher KSI share than vehicle-only crashes: the city-supplied ped/bike dataset showed about 15.4% of ped/bike crashes were KSI, versus roughly 2% among vehicle-only crashes in the ADOT dataset.

Why it matters: Commissioners heard that the distribution of serious crashes is not uniform. Consultants’ maps and heat maps show the greatest concentrations of crashes — and the highest counts of KSI events — in South Scottsdale and through portions of Old Town, with many pedestrian and bicycle incidents occurring at or near intersections.

Key findings and patterns presented

- Crash types: rear‑end crashes are the most frequent overall; however, angle and left‑turn related collisions, as well as head‑on and single‑vehicle crashes, are disproportionately represented among KSI events. For ped/bike crashes the consultants reported nearly three-quarters of incidents fall into angle, head‑on or left‑turn types, and many are coded as intersection‑related.

- Location and time: KSI ped/bike crashes are over‑represented in dark (non‑daylight) conditions. Consultants showed a notable clustering of ped/bike KSI crashes after sundown in the Old Town / South Scottsdale area.

- Contributing factors: alcohol involvement was present in a larger share of KSI crashes (consultants reported about 13.3% of KSI crashes involved alcohol, versus ~6% of total crashes). Motorcyclists were also overrepresented among KSI units in vehicle‑type summaries.

- Data limitations: the team cautioned that police‑reported data include known limits (missing or estimated fields such as officer‑estimated speeds or unknown vehicle types). Dr. Russo noted narratives and officer diagrams can clarify causes but are not uniformly available for every record.

Commissioner questions and staff responses

Commissioners pressed the team on several practical points: what buffer was used to classify an intersection crash (the team used 150 feet for some vulnerable user intersection buffers and 75 feet for bus‑stop proximity summaries), whether bus boardings and transit schedules were cross‑referenced with crash times (staff said not yet but agreed it is feasible), and how crash frequency compares to roadway traffic volumes (consultants said they will compute crash rates using AADT to identify locations with higher crash rates relative to traffic volumes).

Commissioner Pankiewicz (Transportation Commissioner) asked whether single‑vehicle segment crashes had an alcohol signal; consultants said they will summarize alcohol involvement by crash type. Vice Chair Wilcoxon emphasized the importance of observed speed data in assessing pedestrian risk at night; consultants said they are augmenting speed limits with measured speed data from a roadside/mobility data supplier (replica/“synthetic” GPS aggregates) and are piloting locations with MAG to expand coverage.

Staff and consultant recommendations discussed

- High‑injury network: an analysis that blends crash counts with roadway characteristics (speed limit, lanes, functional class, presence of transit stops, land use) to prioritize segments and intersections for countermeasures.

- Site‑level countermeasures: funneling hot‑spot findings into specific engineering remedies (lighting improvements, marked crossings and medians, refuge islands, signal upgrades, flashing yellow arrows, HAWK installations, pedestrian refuges) where warranted and cost‑effective.

- Systemic measures: changes to design standards, enforcement and outreach priorities, improved crash reporting and narrative access, and targeted data collection (speed monitoring, more complete pedestrian/bicycle coding) so interventions can move from spot fixes to scalable policies.

- Equity and grants: staff flagged opportunities under the Safe Streets and Roads for All (SS4A) program, noting that areas of persistent poverty in South Scottsdale may be competitive for SS4A implementation grants if the plan prioritizes those communities.

Follow-up and next steps

Consultants will deliver a more comprehensive crash‑analysis memo, finalize a preliminary high‑injury network, and bring countermeasure screening and cost–benefit ideas to the commission in coming months. Staff said they will incorporate walk‑audit observations (the project team collected 51 site impressions during a technical advisory group walk audit), pursue additional measured speed data, and explore making crash narratives more accessible for detailed review.

Ending: commissioners and staff agreed the next commission meeting will include a discussion of initial goals and policies for the Strategic Transportation Safety Plan and suggested commissioners review the draft crash memo when released.