1. Traffic Topics Does the Zipper Merge threaten our way of life. Ken E
Traffic Topics Does the Zipper Merge threaten our way of life? Ken E. Johnson Office of Traffic, Safety and Technology

2. Zipper Merge Recent media attention:
“Turns out those “jerks” were right…”
Pioneer Press 5/17/10
“I’ve seen a threat to our very way of life – The Zipper Merge”
Joe Soucheray 5/23/10
We are competing with the world for our message.

3. What have been the problems? Where are we and what is Mn/DOT doing?
Why Zipper Merge?
What are the benefits?
What have been the problems?
Where are we and what is Mn/DOT doing?
We are competing with the world for our message.

4. Terminology
Zipper Merge:
Merging behavior where drivers are encouraged to use both lanes prior to defined merge area
Active Zipper Merge:
Sensors and intelligence telling drivers when to use the Zipper Merge
Passive Zipper Merge:
Signs or PCMS notifying drivers to use Zipper Merge when backups occur

5. Existing Merging Problems
Why Zipper?
Existing Merging Problems
Backups
Can extend beyond the advance warning signs when motorists queue up in a single lane
Can block access or interchanges
Rear end crashes caused by:
Traffic flow disruptions caused by erratic merging along the entire length of the queue during backups
Speed differential between lanes
Increased Road Rage against those “cheaters”
Self-appointed “cops” straddling lanes
It’s perfectly legal…

6. This scenario commonly occurs during lane closures
Why Zipper?
This scenario commonly occurs during lane closures

7. Preferred Traffic Flow — Utilizing Equal Lane Occupancy
Why Zipper?
Preferred Traffic Flow — Utilizing Equal Lane Occupancy

8. 2004 Dynamic Late Merge Study
Why Zipper?
2004 Dynamic Late Merge Study
Four Deployments:
I-494 Northbound in Plymouth
I-494 Southbound in Plymouth
US 52 in St. Paul
I-35 around Lakeville
Evaluation of 2004 Dynamic Late Merge System by URS

9. Dynamic Late Merge Study (2004) Before and After Deployment
Why Zipper?
Dynamic Late Merge Study (2004)
Before and After Deployment

10. Findings and Results of 2004 Dynamic Late Merge Study
Why Zipper?
Findings and Results of Dynamic Late Merge Study
Not enough info to evaluate crashes but it was clear:
Reduced aggressive driving
Less confusion
Queue Lengths were reduced by 40%
Lane occupancy increased everyday during congestion - reached near equal lane occupancy after short duration
Throughput not increased – 1600 vph

11. Passive Zipper Merge Why Zipper? Signs added:
USE BOTH LANES DURING BACKUPS
TAKE TURNS AT MERGE
Used over the past few years successfully
I-35 between Pine City and Hinckley
I-35 near Faribault and Owatonna
Hastings bridge maintenance project
State Highway 61 in St. Paul Park
I-494 in Woodbury
Similar benefits to what was found in the DLMS

12. Expected Benefits Speed differential reduced
No Zipper - 1 lane stop and jerk and 1 lane fast
Both lanes moving at same speed
Reduced length of queue
Theoretically up to 50%
Reduced blocking of accesses and interchanges
Fair
Both lanes are equally disadvantaged by the backup
Reduced Road Rage
More protection for work area when both lanes have queues
But – it won’t get you through faster

13. Problems? Inconsistent application Some mixed messages
Advance warning sign that tells the driver which lane is closed
Some road rage issues even at locations signed for Zipper
Online Community Surveyed
80% Early Mergers
2/3 unhappy about late mergers
14% would block late mergers
40% Zipper Merge concept is new to them
Statewide Work Zone Safety Committee
We know it works, what can we do?

14. Where are we? What is Mn/DOT doing? Decision made:
Work to change typical driver behavior to do the Zipper Merge as standard
When driving highway speeds – merge early
When backups occur – use both lanes
How:
Public education effort
More standard implementations of Zipper Merge
Construction
Maintenance
In Metro – will implement when volumes exceed 1800 vph (Lane Closure Manual)

15. Layouts…

16. Layouts…

17. Where are we? What is Mn/DOT doing? CO Communications:
Working to develop Public Education blitz
CO Traffic:
Created layout for Field Manual
Trying to get funding for signs for Maintenance
Construction:
Received Destination Innovation Funding to implement for 2011 construction projects
Active Zipper Merge systems in Metro projects
Stopped Traffic Ahead systems in Greater MN projects
Maintenance:
Implement Zipper Merge where appropriate

18. Resources… Handout available on web: Late Merge…the Zipper System
Google mndot zipper
Layouts in the Field Manual
Dynamic Late Merge System information
Dynamic Late Merge System Evaluation
DLMS Video

19. Taupo, New Zealand – Courtesy of Derrick Dasenbrock
Not the only ones
Taupo, New Zealand – Courtesy of Derrick Dasenbrock

20. Final thought…
When you go to the grocery store – what line do you get into?
Why are highway projects different?

21. Questions?