Edward L. Fischer P.E.

 Ed, it was hard to read slides from back of room with this background.  Can I change it? Nancy Brickman

 Highway Users relate Speed to:  Economics  Time  Comfort  Convenience  Safety Edward L. Fischer P.E.

Interstates Highway/Arterial Collector Local

Fatalities per 100 Million Vehicle Miles (FARS, Highway Statistics 2002)

 Establishing Highway Design Elements:  Horizontal & Vertical Curvature  Superelevation  Gradient & length of grade  Passing & No-passing zone lengths  Sight Distances  Sign Size and Placement Edward L. Fischer P.E.

 Measures speed of vehicles at a specific location  Samples used to estimate the speed characteristics of traffic population  At specific location  Under prevailing conditions at time of study Edward L. Fischer P.E.

 Locations:  Located to meet study purpose  Tangent sections away from controlled intersections  Equipment & Observer  Concealed if possible  TE Cars should be unmarked  Procedure  Record free-flow vehicles  Do not record all vehicles if gaps are < 4 seconds  Avoid peak volume times Edward L. Fischer P.E.

 Establishing Speed Zones  Timing Traffic Signals  Check complaints on speeding  Enforcement Locations  Posting advisory safe speeds  Analyzing crash experience  Before-After studies to evaluate changes in conditions  Speed trends by periodic studies at same point Edward L. Fischer P.E.

 Drivers  Age  Knowledge, Experience  Risk Aversion  Sobriety  Trip Distance: Further – Faster  Distraction Edward L. Fischer P.E.

 Vehicles  Performance Capabilities: Power, Braking, Handling, Traction  Size: Width, Length, Weight, Driver Height  Age of Vehicle  State of Repair  Commercial Vehicles Edward L. Fischer P.E.

 Roadway Characteristics:  Functional Class  Curvature  Grade and Length of Grade  Sight Distance  Lateral Clearance Edward L. Fischer P.E.

 Roadway Characteristics (cont'd):  Number & Width of Lanes  Roadside Development  Frequency of Intersections  Surface Type  Presence of Bicycles or Pedestrians Edward L. Fischer P.E.

 Other Factors:  Other Traffic – speed, volumes (congestion)  Weather  Time of Day  Speed Limits  Enforcement Levels  Jurisdiction Reputation ("Speed Traps") Edward L. Fischer P.E.

Driver Characteristics: Age Risk aversion Experience etc. Vehicle Characteristics & Performance Speed Limits & Enforcement Levels DRIVER CHOICE OF SPEED & ROUTE Traffic Flow Characteristics Roadway Characteristics Weather Time of Day Distribution of Speeds Crash Probability and Severity Other Drivers Vehicles Roadway Environmental Factors Edward L. Fischer P.E.

Why have speed limits?Why have speed limits? How do we set speed limits?How do we set speed limits? Some basic principles in setting speedsSome basic principles in setting speeds

 Limit the upper speed cho  Limit the upper speed choices  Reduce crash severity  Encourage more uniform speeds  Fewer conflicts = fewer crashes  Provide a standard for enforcement  Most effect for $$  More orderly flow of traffic  More efficient sharing of road Edward L. Fischer P.E.

State statue ORS and ORS give Oregon motorists the following statutory speed standards: 15 mph Alleys and narrow residential streets residential streets 20 mph Business district and school zones Edward L. Fischer P.E.

25 mph Residential districts, public parks and ocean shores Edward L. Fischer P.E.

55 mph Rural highways, trucks on interstate highways 65 mph Passenger vehicles, light trucks and motor homes on rural interstate highways Edward L. Fischer P.E.

ORS gives the Oregon Department of Transportation the authority to establish speeds on highways (public roadways) in the state. Edward L. Fischer P.E.

 Uniformity: make sense of driving no matter where you roam  Based on research and national practices  More local the road = More local discretion Edward L. Fischer P.E.

COMMUNICATE  NEIGHBORHOOD REQUEST  AGENCY REQUEST  INVESTIGATION  RECOMMENDATION  REPLY ¯ OK = Speed Zone Order ¯ DISAGREE = Review &/or Public Hearing City or County State Traffic Engineer Edward L. Fischer P.E.

 Speed Zone Review Panel was created for deciding contested speed zone cases  The Panel consists of the following Representatives:  ODOT  State Police  Oregon Transportation Safety Committee  League of Oregon Cities  Association of Oregon Counties

INVESTIGATE Type of street Type of street Roadside culture Roadside culture Accident history Accident history Traffic mix and speeds Traffic mix and speeds Average, 85 th percentile, pace limits Average, 85 th percentile, pace limits Traffic volumes Traffic volumes Roadway alignment Roadway alignment Width Width Surfaces Surfaces Edward L. Fischer P.E.

Number of Drivers Average Speed 85%15% 50% Speed at which 85% of the vehicles are traveling at or below

Target Enforcement 85thPercentile 85th Percentile Safety & Enforcement

How does it work? It is based on the assumption that most people are reasonably prudent & choose to drive at a safe speed It saves enforcement resources for high risk takers It encourages more uniform travel speeds, reduces conflicts 85% 42 MPH Edward L. Fischer P.E.

Are clearly reasonable to the driver Edward L. Fischer P.E.

Are clearly reasonable to the driver

Sidewalks define an urban street What’s more likely to slow traffic? Most effective is road design Edward L. Fischer P.E.

Adding vertical elements and creating “friction” to sides of road can be very effective in slowing traffic

Most downtowns have a good “height-to-width” ratio Traffic slows down accordingly

No point in posting this street at 25 MPH!

Is a 25 mph speed limit sign needed here? Edward L. Fischer P.E.

Enforcement can target a small percentage

 Posted speeds are clearly reasonable to the driver  Most effective is road design  Enforcement can target a small percentage  Enforcement should be constantly visible Edward L. Fischer P.E.

QUESTIONS? Wake Up Try to look interested Edward L. Fischer P.E.