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Data & Maps

Alto DOT collects and publishes transportation data. Publishing it serves two purposes: it lets residents check the city's reasoning rather than take it on faith, and it lets anyone proposing a change argue from the same numbers DOT uses.

Maps​

  • Web Map — the city's interactive map, including live closures, construction, and detour routes
  • Street classification map — the functional class of every city street, which determines design standards and maintenance priority
  • Bikeway and trail network map — existing and planned facilities; see Active Transportation
  • Transit network map — routes, stops, and connections; see Transit
  • Truck route map — designated routes for through freight movement
  • Signal location map — every signalized location under city jurisdiction

Data Sets​

Data setContentsUpdate cycle
Traffic countsDaily and peak-hour volumes at count locations, with class and directionRolling, by corridor
Speed studiesMeasured operating speeds where studies have been performedAs studied
Crash summariesAggregate crash data by location, type, and severityAnnual, with interim updates
High-Injury NetworkThe street segments carrying the concentration of serious crashesWith each safety plan update
Signal inventoryLocation, phasing type, equipment, and last timing reviewContinuous
Signal timing plansCycle lengths, splits, and offsets for coordinated corridorsOn change
Asset inventorySigns, markings, and street furniture in the right-of-wayContinuous
Permit activityActive right-of-way permits and their limitsDaily

Requesting Data​

Data not published here can be requested. Common requests — a count at a specific intersection, the timing plan for a particular signal, the crash history of a corridor — are usually filled directly by the Traffic Engineering Division.

Requests that require original data collection may take longer or may be scheduled into an existing count program. Formal records requests go through Public Records.

Notes on Using the Data​

A few cautions, so the numbers are read the way they were measured:

  • Counts are samples. A count taken on a Tuesday in October is not a statement about every day of the year. Seasonal and day-of-week variation on the causeway routes is substantial.
  • Crash data undercounts. Crashes without injury or significant property damage are frequently unreported, and pedestrian and bicycle crashes are underreported relative to vehicle crashes. Absence of recorded crashes is not evidence of safety.
  • The 85th percentile speed is an input, not an answer. It describes how fast people currently drive, which is partly a product of how the street was built. It does not by itself establish what the speed should be.
  • Signal timing is context-dependent. A timing plan taken out of its corridor context will not reproduce the behavior observed in the field.
  • Volumes reflect the network as built. Traffic counts measure the trips the current network permits, not the trips people would make on a different one.

Privacy​

Published data is aggregated. DOT does not publish data that identifies individuals, and detection equipment at signalized locations is used for signal operation and counting rather than for identification.

Contact​