what makes a roadway safe?
Post on 30-Dec-2015
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What Makes a Roadway Safe?
ISLAND COUNTY
PUBLIC WORKS DEPARTMENT
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First off, some facts:• More than one million people are killed
each year on the world’s roadways.
• More people die in the U.S. each month from traffic accidents than died in the September 11 terrorist attacks.
• U.S. Traffic Accidents cost more than $150 billion annually.
• Rural two-lane roads represent 80% of all U.S. Highways and most lanes are less than 11 feet wide.
• Rural two-lane roads experience higher rates of accidents than freeways.
• Wider lanes and shoulders are among the most effective means of improving rural roadway safety.
Shoulders Provide:
• Space to escape serious accidents
• Space to pull over because of vehicle malfunction
• Space to pull over to let emergency vehicles respond
• Improved sight distance
• Space for bicycle and pedestrian use
• Space for bus stops
• Space for plowed snow and maintenance operations
• Reduction of storm water degradation of pavement
Some Roadway Considerations:
• Sight Distance - ability to see and anticipate ahead
– Topography - hills vs. flat ground
– Horizontal Curves
• Posted speed vs. driver speeds
• ADT - Average Daily Traffic
• Types of traffic - cars, trucks, buses, bicycles, pedestrian
• Type of service - residential, collector, arterial
• Uniform dimensions to conform with roads elsewhere
Roadways Aren’t Just Pavement;They also provide:
• Stormwater treatment with grass strips and swales
• Stormwater runoff absorbed with infiltration trenches
• Embankments, cut slopes and retaining walls
• Signage and utilities set back from edge of roadway
• Driveway accesses with safe sight distances
• Vegetation to control erosion and enhance the view
What are My Chances?
• Q: I drive all the time. When am I more likely to be involved in a car accident?
A: Double-check your seatbelt on Saturday, by far the most likely day for an accident. The worst time is between 10:00 pm and 2:00 am.
• Q: How much safer is my big fat SUV?
A: Some say not at all. Although very large vehicles offer more protection in an accident, they are far more likely to be involved in an accident in the first place.
• Q: Which groups are least likely to wear a seatbelt?
A: Those with the least common sense: minors, drunks and males.• Q: What is my most dangerous toy?
A: Your bicycle accounts for almost 400,000 emergency room visits per year. (Well, ok, not your bicycle).
Reprinted with permission from Whidbey Printers, “Facts of Life”, May 2003
Sidewalks
• Vertical and/or lateral separation from roadway
• Minimal grades and drop-offs
• Minimal cross-slopes
• Minimum Width to allow two-way pedestrian traffic
• Easily maintained
• Meets ADA standards (mobility)
• Clearances of 8 feet above sidewalk
• People prefer straight lines; Point A to Point B
• Determine pedestrian destinations and align to serve the greatest amount of pedestrian traffic
II know no safe depository of the ultimate powers of the society but the people themselves;
and if we think them not enlightened enough to exercise their control with a wholesome discretion,
the remedy is not to take it from them, but to inform their discretion by education
Thomas JeffersonSeptember 28, 1820
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