Scottsdale consultants cite South Scottsdale, Old Town as crash hot spots in preliminary safety analysis

Consultants told the Scottsdale Transportation Commission on April 17 that a preliminary analysis of 2019–2023 crash records shows nearly 19,000 reported crashes citywide and roughly 500 suspected fatal or serious‑injury (KSI) crashes, with pedestrian and bicycle collisions disproportionately represented among the most severe outcomes.

The analysis, led by consultants from T.Y. Lin and Northern Arizona University and introduced by City staff, found 18,000 vehicle‑only crashes in ADOT records supplemented by the city’s pedestrian and bicycle crash file (about 700 ped/bike crashes). Consultants said about 2 percent of vehicle‑only crashes were KSI, while 15.4 percent of the city’s ped/bike crashes were KSI. Heat maps and intersection blowups showed the highest concentrations of total and KSI crashes in South Scottsdale and Old Town.

Why it matters: the city is assembling a Strategic Transportation Safety Plan intended to guide capital projects, countermeasures and grant applications. Commissioners pressed consultants on data limits and prioritization so the plan will steer funding — including federal Safe Streets for All (SS4A) opportunities — toward the corridors and locations that most affect vulnerable road users.

Most important findings and methods

- Timeframe and sources: consultants used a five‑year police‑reported dataset covering 2019–2023 combining ADOT records (vehicle crashes) and a City of Scottsdale file for pedestrian and bicycle crashes.

- Scale and severity: the combined dataset showed just under 19,000 crashes and just under 500 KSI (fatal or suspected serious injury) crashes over five years. Consultants said vehicle‑only crashes were roughly 18,000 with 376 KSI; ped/bike crashes numbered about 700 with a higher KSI share (15.4%).

- Collision types and locations: rear‑end crashes were the most common overall; angle and left‑turn collisions were overrepresented among KSI and among ped/bike crashes. Mapping showed many ped/bike crashes coded at or within intersections and crosswalks.

- Lighting, time of day, alcohol and vehicle type: consultants reported a higher share of KSI crashes occurring in non‑daylight conditions (dark but lighted most common), and that pedestrian KSI crashes were overrepresented at night. Alcohol was recorded in about 6 percent of total crashes and 13.3 percent of KSI crashes. Motorcyclists were overrepresented among KSI involvement in vehicle‑type summaries.

- Analytical buffers and supplementary data: for the presentation consultants used a 150‑foot buffer to identify “intersection” ped/bike crash proximity and a 75‑foot buffer for bus stop proximity; they said they plan to augment speed‑limit fields with measured speed data from Replica (synthetic GPS data) and MAG pilot sites.

Data limitations flagged by presenters and commissioners

Consultants and staff repeatedly noted limits of police‑reported crash data: fields that rely on officer judgment (for example, estimated speed) can be incomplete or inconsistent, and narratives/diagrams are not uniformly available. Dr. Russo (NAU) said, “we’re working with police‑reported crash data here, and there are inherent limitations,” and recommended supplementing records with measured speed data and targeted narrative review to improve cause‑of‑crash understanding.

Commissioners asked for several specific follow‑ups: compare crash rates using annual average daily traffic (AADT) so lower‑volume streets with high crash rates can be identified; produce alcohol‑by‑crash‑type summaries; expand the list of high‑injury locations beyond a demonstration “top five” to a full high‑injury network; and examine seasonal and transit‑schedule correlations (several commissioners suggested comparing crash times with bus operation hours).

Community observations and qualitative data

Consultants described a four‑stop walk audit that produced 51 recorded impressions from technical advisory group members, with recurring comments about crosswalk quality, curb ramps and pedestrian access from adjoining land uses (for example, retaining walls that force circuitous pedestrian routes). Staff and consultants said those qualitative observations will be combined with quantitative crash and roadway data when prioritizing countermeasures.

Programmatic and countermeasure approach

Consultants outlined a two‑track approach: site‑level countermeasures (specific intersection/segment engineering and benefit‑cost estimates using crash modification factors) and system‑level measures (design standards, enforcement strategies, improved crash‑report narratives and training). They recommended exploring lighting improvements on corridors with a pattern of nighttime KSI crashes, and flagged opportunities to bundle corridor lighting, speed management, and pedestrian visibility for grant competitiveness under SS4A and similar programs.

What commissioners directed or asked staff to do

- Add measured speed data where possible (Replica, MAG pilot sites) and calculate crash rates using AADT; several commissioners specifically asked for speed and crash‑rate summaries. - Expand the high‑injury network beyond demonstration top‑five lists and present a prioritized set of locations with a rationale for selection. - Investigate making crash narratives and officer diagrams more available to staff or automating parts of the data merging process between City records and ADOT files. - Consider land‑use controls and development review language to require more direct pedestrian access where retaining walls or site layout forces unsafe crossings.

Quotes (from meeting transcript)

“this is very much a check‑in at this point at a high level to sort of get some feedback,” said Ryan, Senior Transportation Planner, T.Y. Lin.

“We’re working with police‑reported crash data here, and there are inherent limitations,” said Dr. Russo, NAU, urging use of measured speed data and additional narrative review.

Next steps and timeline

Consultants said they will deliver a more comprehensive crash‑analysis memo and a draft high‑injury network, and will follow with a countermeasures package that includes site‑level and system‑level options. Staff noted a follow‑up public discussion of draft goals and policies is scheduled for the May commission meeting; consultants said improved crash narratives, added speed data, and coordinated work with MAG on measured data are priorities before finalizing recommendations.