1. Efficient Traffic Flow:
Creating Safe and
Efficient Traffic Flow:
GDOT I-285 Increased Speed Limit and Variable Speed Limits Project

2. Agenda Project Background Action Plan What are VSLs? Why is it needed?
How it will work
Discussion and Questions

3. Project Background Project location: I-285 Project Goals:
Increase speed limit to 65 mph during non-congested times
Provide consistent travel times
Reduce accidents (primary and secondary)
Decrease sudden stops by slowing traffic in advance (reduce accordion effect)

4. Action Plan
The general speed limit on I-285 will be raised from 55 mph 65 mph.
The north side of I-285, (above I-20) is being transitioned to variable speed limits (VSL).
The speed limit will be adjustable between 65 mph and 35 mph, depending on road conditions,
Expectation that the speed limit will remain at 65 mph the majority of the time.
Speed limit will be adjusted at 10 mph increments.
The southern portion of I-285 (below I-20) will have the speed limit raised permanently to 65 mph.
The general speed limit on I-285 will be raised from 55 mph 65 mph, the highest allowed by law for an urban highway.
the north side of I-285, where traffic flow is heavier, is being transitioned to variable speed limits (VSL).
The speed limit will be adjustable between 65 mph and 35 mph, depending on road conditions, with the expectation that the speed limit will remain at 65 mph the majority of the time.
When the speed limit is adjusted it will be at 10 mph increments.
The southern portion of I-285 that is not undergoing the change to variable speed limits will have the speed limit raised permanently to 65 mph.

5. This color signifies the portion of I-285 that will undergo the change to VSLs from 35 mph up to the new increased speed limit of 65 mph
This color signifies the portion of I-285 that will permanently change to a 65 mph speed limit

6. What are Variable Speed Limits (VSLs)?
VSL systems are a type of Intelligent Transportation System (ITS) that utilize current traffic speed and volume detection, weather information, and road surface condition technology to determine appropriate speeds for safe travel.
VSL systems are usually part of a larger incident management, congestion management, weather advisory, or motorist warning system.

7. Why is it needed?
Traffic studies of I-285 have shown that an increased speed limit is warranted.
Northern half of I-285 much more congested;
carrying significantly more traffic each day than the southern half
an average of 50,000 more vehicles and in some sections as many as 100,000 more.
There also are more interchanges on the northern section (28) than the southern (15).
more weaving and more merging for drivers
Both increase the risk of accidents

8. Why is it needed? Higher traffic volumes on northern section of I-285
traffic flow often deteriorates into a constant accelerating/braking process
very inefficient and dangerous
Studies show that by travelling at a slower but more consistent speed
eliminates accordion-like, stop-and-go pace,
Motorist save on gasoline,
Arrive at their destinations sooner

9. How it will work:
Posted speed will be based on current speeds measured by roadway sensors (max 65 mph; min is 35 mph)
Posted speeds will be updated automatically via NaviGAtor II (NAVII)
Logic will include:
When to increase the speed
When to decrease speeds
How often speeds can change
TMC can also override to manage the VSLs as conditions warrant
Incidents
Events
Weather

10. How it will work: VSL signs are regulatory and enforceable
Overhead dynamic message signs will advise motorists in advance of an upcoming reduction in the speed limit
Motorists will be advised of the reason for the speed limit change
An array of LED speed limit signs will replace static signs on the outside shoulder and center median

11. Next Steps Key element to the future success Education Enforcement
Web page
Video
Information meetings
Letters to stakeholders
Media relations
Enforcement
These will lead to greater driver understanding and compliance.

12. Brief history of VSLs 1960 – Michigan – Congestion Mitigation
1960’s (late) – New Jersey – Congestion Mitigation
1989 – New Mexico – Congestion Mitigation
1995 – Colorado – Tunnel Truck Speeds
1998 – Arizona – Experimental – Weather Conditions
More recent:
I-270/I-255 Missouri – Congestion Mitigation (2008)
I-4 Orlando – Congestion Mitigation (2010)
“Smarter Highways” Washington – Congestion Mitigation (2010)
United Kingdom – Congestion Mitigation (2006)

13. Questions?

14. Contacts Kathy Zahul Andrew Hoenig State Traffic Engineer
Andrew Hoenig
Project Manager