I-16/I-75 Improvement Project
Advisory Committee Meeting Summary
Centreplex
August 3, 2000
4:00-6:00p.m.

Advisory Committee Participants:
Elaine Bolton, Macon Heritage Foundation
Grace Bunner, Native American Council
Connie Mac Darnell, Newtown Macon
Jim David, Ocmulgee Nat'l Monument
Daniel Fischer, Caution Macon
Joel Harrell, Norfolk Southern
Regina McDuffie, Centreplex
Paul Nagle, Chamber of Commerce
Anita Ponder, City Council
David Stanley, Minister
Johnny Wingers, Bibb Co. EMA
Sid Cherry, Downtown Council
Sandra Bush, Resident

Project Team Participants:
Joseph Palladi, GDOT
Angela Alexander, GDOT
Rebecca Gifford, GDOT
David Miller, GDOT
Genetha Rice-Singleton, GDOT
Bob Chaapel, FHWA
Brad Hale, MAAI
Garrett Sauber, MAAI
Glenn Scarborough, MAAI
Karla Poshedly, MAAI
Todd Hill, MAAI
Melissa Moreland-Bourbeau, MAAI
Jeff Gardner, Brockington & Assoc.
Tim Heilmeier, HNTB
Liz Sanford, Sycamore Consulting
Denise Watts, Sycamore Consulting

Discussion Summary

The following people would be joining the group as new members of the Advisory Committee:

Ms. Sandra Bush, Macon resident and member of the Pierce / Arkwright Advisory Committee
Ms. Elaine Bolton, Macon Heritage (replacement for Ms. Maryel Battin)
Ms. Grace Bunner, Native American Council
Mr. Richard Enesley, Pleasant Hill resident

The primary purpose of the meeting was to review the remaining concept alternatives and identify a preferred alternative, and then discussed the criteria to be used in evaluating the alternatives.  This included an explanation of level of service (LOS), highway capacity software (HCS), average daily traffic (ADT), design hourly volume (DHV), and stopping sight distance.  The different LOS ratings were explained from A to F.

The project goal, which includes a detailed color matrix chart listing each alternate with a rating of excellent, good needs improvement or unacceptable in relation to the projects goals was given to each ACM member.  A new concept alternative (alternative #7) was introduced as a hybrid of earlier concepts, incorporating their most desirable features.

Before continuing further with a discussion of how each alternative was evaluated, two outstanding issues from previous ACM’s were discussed:
  • The suggested half diamond interchange of Riverside Drive and I-75, relocating the Norfolk Southern railroad
  • A left hand exit ramp from I-75 SB to Riverside Drive via the former K-Mart parking lot

I-75 / Riverside Drive half diamond interchange

Due to the close proximity of Riverside Drive to Hardeman Avenue, the proposed ramps from Riverside Drive to I-75 (NB exit ramp and SB entrance ramp) would need to be braided with the ramps from Hardeman Avenue to I-75 (NB entrance ramp and SB exit ramp).  Ramps from Riverside Drive connecting directly with the core lanes of I-75 would not have enough distance from the Hardeman Avenue ramps to satisfy AASHTO and MUTCD criteria (i.e. unsafe weaving movements would occur).  Engineering diagrams were used to show how the construction of braided (grade separated) ramps would greatly impact the Pleasant Hill District.

A traffic engineer with MAAI explained how the traffic had been analyzed at the Hardeman Avenue/Forsyth Street at I-75 and Spring Street at I-16 interchanges with and without the half diamond interchange at Riverside Drive.  It was shown that the only intersection where the (LOS) improved was the I-75 NB exit ramp at Forsyth Street.

Norfolk Southern Railroad Relocation

MAAI has performed a study to assess the changes that would be necessary to the I-16/I-75 interchange project in order not to preclude a separate project to relocate the Norfolk Southern railroad.  Four possible alternatives for the railroad relocation were looked at as part of this informal study.  These alternatives included:
  • Relocating the existing railroad to the North side of the Ocmulgee River.
  • Enclosing the existing railroad in a structure.
  • Relocating the existing railroad to another railroad line.
  • Constructing a Macon rail by-pass on new location.

After a brief discussion of the pros and cons for each alternative, it was concluded that relocation of the railroad within the limits of the project would not be feasible due to the elevation changes necessary to span the Ocmulgee River at the 100 year flood stage.

Miscellaneous Alternatives

E-mail was received requesting GDOT to examine a left hand exit from I-75 SB to Riverside Drive via the K-Mart parking lot.  Neither GDOT nor FHWA would approve a design with a left hand exit from the interstate.  The geometric of such a ramp would be undesirable and it would be difficult to prevent motorists from accidentally turning onto the ramp from Riverside Drive and going the wrong way.

A committee member asked about the possible Emery Highway Flyover Bridge to I-16.  It was intended to have the ramp extend from Emery Highway SB directly to I-16 WB, which would alleviate traffic at the Spring Street intersection.  The analysis of this shows a connection from I-16 EB to Emery Highway NB.  Essentially the same problems would result.  Grade changes on Emery Highway would be severe.  In addition, this ramp would create a bad-weaving section on the WB collector distributor (CD), introducing a full interchange at Second Street would accomplish this same movement and at a much cheaper cost.

Concept Alternatives - Analysis & Selection

The six alternative concepts and the initial concept (prepared by GDOT for cost estimating purposes) were reviewed briefly.  The committee due to the following fatal flaws eliminated four of these alternatives:
  • Initial Concept - Unacceptable impacts to cultural resources (TCP and Ocmulgee National Monument).
  • Alternative #4 - Poor driver expectancy due to left hand exits from EB I-16 CD road.
  • Alternative #5 - Poor driver expectancy due to left hand exits from EB I-16 CD road.  Undesirable one-way operations on Spring Street and 2nd Street.
  • Alternative #6 - Poor driver expectancy due to left hand exit from EB I-16 CD road.  Undesirable one-way operations on 2nd Street and Coliseum Drive.

The remaining three conceptual alternatives (1, 2, & 3) and a new hybrid concept (Alternative #7) were then discussed.  Line diagrams and the goals matrix were used to discuss the pros and cons of the remaining alternatives.

Alternative #1 - Alternative #1 was discussed in detail with several engineers from the consultant team offering explanations of various design criteria.  The following is a list of the areas that the consultant outlined as needing improvement:
  • Poor signage.  A single Interstate sign containing multiple destinations is undesirable.  This alternative would require signage for three exits (Spring Street, 2nd Street, and Coliseum Drive) at a single location.
  • The EB I-16 CD road between I-75 and Spring Street has an undesirable weaving section.
  • The WB I-16 CD road has a non-directional split at the I-16/I-75 interchange.  This would result in poor driver expectancy.
  • An unsafe condition occurs where the WB CD flyover ramp merges with the WB I-16 ramp immediately prior to a merge with SB I-75.

Although none of the problem areas mentioned were considered fatal flaws, it was agreed that Alternative #1 needed improvement.

Alternative #2 - It was pointed out that the primary goal with Alternative #2 was to reduce construction costs and decrease the footprint of the project by eliminating the braided ramps.  To accomplish this, the ramp from Spring Street to I-16 EB was routed through an at-grade intersection with 2nd Street.  The traffic studies showed that this intersection, as shown in Alternative #2, would operate at a LOS of F.  Alternative #2, despite several desirable features, was therefore eliminated.

Alternative #3 - This alternative was shown to have some of the same positive features as Alternative #2 (reduced footprint and reduced construction costs), but some of the same negative features as Alternative #1 (poor signage, bad weave on CD road, non-directional split, and bad merge at I-75 SB).  The traffic study for this alternative showed that the proposed Spring Street/EB CD road intersection would operate at a LOS of E.  Since the objective of these roadway improvements is to achieve LOS D or better, Alternative #3 was formally eliminated.

Alternative #7 - Alternative #7 was then introduced to correct the deficiencies described in Alternative #1 while incorporating several positive features from Alternatives #2 and 3.  The following is an outline of the problem areas from previous alternatives and how Alternative #7 corrects or improves these areas:
  • Interstate signing.  Several of the previous alternatives had up to five destinations at a single decision point, which can create erratic and unsafe lane changes due to poor driver expectancy.  Alternative #7 corrects this problem by separating the Spring Street ramps from the EB CD road.  This resulting EB CD road only requires signing for two destinations and places the exit nearly one-half mile closer to the destination points.  This is a much more desirable situation for driver expectancy than that of Alternative #1.
  • Non-directional split from WB CD road to I-75 NB and SB.  The ramps in question were simply reversed and pulled closer to the mainline (compare line diagrams for Alternatives #1 and 7&341;.  The resulting ramps for Alternative #7 will have a directional split, i.e. the ramp to the right continues to the right on I-75 NB, and the ramp to the left continues to the left on I-75 SB.  This should improve driver expectancy for motorists approaching the I-16&347;I-75 interchange.
  • Unsafe merge of three ramps feeding I-75 SB.  The flyover ramp from the WB CD road to I-75 SB was modified with Alternative #7 to merge with I-75 on the right instead of merging with the ramp from I-16 WB (please reference line diagram).  This removed the undesirable merge of three ramps within close proximity.
  • Undesirable weaving sections on CD roads.  By separating the Spring Street ramps from the CD roads as shown on Alternative #7, all resulting CD road and mainline weaving sections operate at a LOS of C or better.
  • Property impacts.  The ramps and CD roads between 2nd Street and Coliseum Drive were reconfigured with Alternative #7 to eliminate the braided ramps shown with Alternative #1.  This should result in a more "compact" design requiring less.
  • Right-of-way from the Macon Centreplex and less impact to the 100-year floodplain.

The Advisory Committee agreed to move forward with Alternative #7 as the preferred alternative.

"Parking Lot" and Follow-up Items

There were a few more topics added to the "parking lot" that could not be addressed at this meeting, or should be considered for future meetings.  These included:
  • Several committee members requested to see a signage plan, including informational signs for the Ocmulgee Nat'l Monument and the Macon Coliseum.
  • Pedestrian facilities need to be addressed in preferred alternative.
  • More detailed displays for the preferred alternative, including the plan view on aerial photography and cross-sectional views to illustrate the elevations of the new ramps and roadways.

In closing, it was agreed that the committee would meet before the next public meeting.  Details regarding the time and location of the next committee meeting and the PIM will be provided at a later date.

The meeting was adjourned to a future date to be determined prior to a second Public Informational Meeting.



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