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Traffic Safety

Alto DOT's traffic safety program works from the position that serious crashes are predictable and preventable, and that the street itself is one of the things that determines how badly a mistake ends. People will always make errors. A well-designed street keeps an ordinary error from being fatal.

The Approach​

Alto's safety program rests on a few principles that shape every design decision:

  • Speed is the variable that matters most. The probability that a person struck by a vehicle is killed rises steeply with impact speed. Designing a street so that its comfortable driving speed matches its intended speed does more for safety than any amount of signing.
  • Design for the errors people actually make. Sight distance, clear signal indications, forgiving geometry, and separation of conflicting movements reduce both the chance of a mistake and its cost.
  • Concentrate on the network, not just the location. A small share of streets carries a large share of serious crashes. Systemic treatment of that subset is more effective than responding site by site.
  • Count everyone. A street that moves vehicles efficiently while making crossing dangerous has not succeeded; it has moved its cost onto people not counted in the measurement.

The High-Injury Network​

DOT maintains a High-Injury Network: the subset of city streets on which serious and fatal crashes concentrate. Identifying it allows systemic treatment — applying a proven countermeasure across every location sharing a risk factor, rather than waiting for each one to accumulate its own crash history.

The network is reviewed as new crash data becomes available, and it drives prioritization in the capital program.

Countermeasures​

ProblemTypical countermeasures
SpeedingLane narrowing, curb extensions, geometric changes, signal timing, speed limit set from a proper study
Intersection crashesSight distance improvement, turn phasing changes, turn restrictions, geometry, lighting
Pedestrian crashesCrossing treatments, refuge islands, curb extensions, leading pedestrian intervals, lighting
Red-light runningSignal timing review, yellow change and red clearance interval adjustment, visibility improvements, advance warning
Roadway departureClear zone management, delineation, curve warning, pavement friction
Wrong-way movementsSigning and marking, geometric changes, straight-through arrow signal faces
Restricted signal visibilityHead size, additional faces, visibility-limited faces, strobe-equipped red indications

Two of these are specific to the UIA: the through-arrow signal faces and strobe-equipped red indications permitted by the UIA MUTCD addenda. Both exist for the same reason — making the correct action unmistakable at a location where the conventional treatment has not been sufficient.

Crash Data and Analysis​

DOT reviews crash records to identify patterns, evaluate completed projects, and prioritize future work. Analysis considers crash type, severity, contributing conditions, time of day, and the movements involved, rather than raw crash counts alone: a location with many low-severity crashes and a location with a few fatal ones call for different responses.

Crash records are maintained by the DMV and by APD. Aggregate safety data is published through Data & Maps.

Speed Management​

Speed limits in Alto are set from engineering study, not by request or by petition. A study considers measured operating speeds, roadway context, crash history, pedestrian activity, and adjacent land use.

Posting a lower number on a sign does not by itself slow traffic; drivers select speed largely from what the street looks like it permits. Where a lower speed is the goal, DOT pairs the limit with design changes that make the lower speed feel natural.

Work Zone Safety​

Work zones concentrate risk for both road users and workers. Every work zone in Alto operates under an approved traffic control plan conforming to Part 6 of the UIA MUTCD. See Permits.

Enforcement​

Enforcement is carried out by APD. DOT supports it with data on where and when violations concentrate, and with engineering changes where a violation pattern indicates a design problem rather than a behavior problem. A location where most drivers violate a rule is usually a location where the rule and the design disagree.

Reporting a Safety Concern​