Monday, November 7, 2016

I-49 Lafayette Connector Update: Tier II Analysis Nearly Completed, ECI Surface Tunnel Gets Stoned, Elevated Option Most Likely Solution


[NOTE: All illustrations are from the Tier II Draft Technical Memo Findings Report that was introduced to the three I-49 Connector committees on November 4th and 5th; and were posted to the LADOTD Lafayette Connector website on November 5th. The report is downloadable from that website as part of a compressed folder in the "Project Library" section under any one of the relevant committee bar tags.]

------------------------------------------------------------------------------------------------------ 

This week was a long awaited week of movement in plans towards the Lafayette Connector freeway project. The Connector Design Team , under the leadership of the Louisiana Department of Transportation and Development (LADOTD) and the Federal Highway Administration (FHWA), unveiled yesterday the notes and results of their Tier II Analysis of the 2 remaining design concepts for the central core portion of the project; and the report opened and closed many options.

In case you may have missed it: LADOTD had decided after their initial Tier I Concept Analysis back in August to further study 2 conceptual designs for the central core: an elevated freeway mainline with cross streets passing underneath and the Evangeline Thruway used as dispersion between the freeway and downtown; and a partially depressed mainline (10 feet below ground level + 10' above for 20' of vertical clearance) with cross streets passing over the freeway. The latter option was itself divided into two sub-concepts: an open trench with cross-street bridging, and a "surface tunnel" or "cut and cover" option where the freeway would be capped and covered with embankment allowing the cross streets to pass over the tunnel. The "surface tunnel" variation was in direct response to feedback from the Evangeline Thruway Redevelopment Team's Evangeline Corridor Initiative (the program to reconnect neighborhoods affected by the Connector that was partially funded by a federal TIGER grant) and some in the public who wanted what they thought would be a less visually impacting corridor.

The final draft of their Tier II analysis just came in....and it doesn't look too good, unfortunately, for the "surface tunnel" option. Based on the initial scoring and the costs, it looks more and more like the Elevated option, probably with a conversion of the existing Evangeline Thruway core section to a "grand boulevard", will become the chosen alternative for the Connector freeway.

Before we get to the meat of the analysis, a quick review of the background.

------------------------------------------------------------------------------------

FEIS/ROD Selected Alternative/Concept 1A & ECI Alterations

The original Selected Alternative based on the 2003 Final Environmental Impact Statement/Record of Decision is illustrated below.

Original Refinement Concept 1A, consisting of the
Selected Alternative approved through the
2003 Final EIS/Record of Decision

That concept included standalone interchanges with Johnston Street and a consolidated couplet of Second and Third Streets, a mostly elevated mainline on structure (except for a section on fill between Jefferson and Johnston Streets, railroad grade separations with the above mentioned interchange locations (along with the current Jefferson Street underpass), and maintaining the existing Evangeline Thruway one-way couplet as part of the frontage road system.

Most local officials immediately panned this alternative because, according to them, the interchanges and underpasses took up too much space that could be more useful for economic development, the filled embankment section and interchange ramps were too divisive and didn't allow enough connectivity, and the interchanges brought too much traffic into streets that they were trying to downgrade for "Complete Streets" multimodal use (bicycles and pedestrians).

The Connector Design Team responded by opening up the process to allow for "refinements" to the design for the core segment; this produced a total of 19 concept refinement proposals utilizing 6 concepts. It was here that the ETRT and ECI attempted to intervene with their ideas for better neighborhood connectivity and compatibility with "New Urbanism" techniques of broadening mixed use development. In early August, DOTD announced that they would reduce the level of alternative concepts for their Tier 2 series of detailed analysis down to two: the Elevated Mainline (Series 4) and the Semi-Depressed Mainline (Series 6). This was also in sync with the ECI pushing out their own proposed concepts based on those two alternatives. For posterity's sake, here are the two ECI options for the downtown core of Lafayette. (From the ECI's September 27th Charrette Report)




The hope for the ECI was that initial testing did show their Partially Depressed and Covered Mainline to be marginally feasible, and the possibility of huge economic development gains from exploiting the space over the freeway would justify the higher costs as compared to the Elevated Mainline option.

Unfortunately, it appears that those hopes have been dashed to pieces upon further analysis by DOTD engineers.

For the last 2 months, DOTD and the Connector Design Team basically reworked and tested the Elevated, Partially Depressed/Open Trench and Cut-and-Cover designs, eventually resulting in 4 final proposed design options that were presented this week. Let's go through each one individually:

-----------------------------------------------------------------------------------

1) Concept 4-1: Elevated Mainline with Evangeline Thruway Couplet


There are some aspects where the Design Team did incorporate some elements desired by the ECI "TIGER Team"; they "flattened" the mainline in the area between Second Street and Taft Street so that it paralleled Chestnut Street and the Burlington Northern Santa Fe Railway (BNSF RR) line; and they did do away with the original plan of a loop ramp at Taft Street for connecting the Thruway to the southbound Connector mainline in favor of a more traditional slip ramp pair to the Thruway at Eleventh Street. In addition, the Elevated Mainline would assume a taller structure for the viaduct; only thing left to be determined would be whether a 22' or 30' vertical clearance would be utilized.

In Concept 4-1, the Evangeline Thruway stays mostly in its existing one-way couplet up to just past Jefferson Boulevard, where it transitions into boulevard-like facility centered on the southbound Thruway roadway, to get away from the Sterling Grove Historical District and the St. Genivieve Catholic Church. It then gets incorporated into the freeway frontage road system, but with the northbound Thruway roadway rebuilt on new alignment parallel to the mainline; the former northbound roadway would be transformed into a local two-way street (Cigg Street before the Thruway was built, maybe??)

Cross section profile for Elevated Mainline

The existing profile for the Elevated concepts allows for a 22 foot vertical clearance under the structure in order to reduce the visual impact to surrounding areas; however, there is an option to even further increase the height to allow for a 30' clearance, which could possibly raise the height of the freeway to as much as 45' above ground level.

I-49 Connector Elevated Profile Heights above current
ground level, reflecting both 22 foot & 30 foot verticals

Another interesting adjustment is that Simcoe Street is essentially severed across the freeway mainline in order to free up more space for mitigating the visual impact on the St. Genevieve Church property. On the west side, Simcoe traffic would be diverted to Chestnut Street and then the Second/Third one-way couplet, which would then tie back into Simcoe on the east side. There would be also a new connection on the west side using the old Dudley Avenue right-of-way to connect with Greig Street. (Dudley Ave. was absorbed by the southbound Thruway when the latter was built.)


Section of I-49 Connector Elevated Option near Sterling Grove
Historical District (Concept 4-1, with One-Way Couplet)

Also noted is that Mudd Avenue, which traverses the Sterling Grove District, is severed between the former northbound roadway/future local street and the rebuilt northbound Thruway frontage road. This is apparently to remove direct heavy traffic access from Mudd eastbound, and to further provide a continuous buffer for homes in Sterling Grove and the St. Genevieve church/school property. Mudd would still have full access to the Thruway frontage system, though, because it would pass underneath the freeway mainline to connect with the northbound roadway. 

Treatment of Mudd Avenue intersecton with
realigned Evangeline Thruway frontage system
under both Elevated concepts (severage between
new northbound Thruway and former northbound
Thruway roadway converted to local street)
The proposals from the Evangeline Corridor Initiative studying means to retain connectivity throughout the Connector freeway corridor originally recommended Mudd Avenue be retained as a continuous arterial across the freeway/frontage system, but with the portion crossing the Sterling Grove Historical District converted into a "Complete Streets" multimodal facility more friendly to bicycle and pedestrian traffic. Both Concept 4 plans differ in that they would sever Mudd between the new northbound frontage road and the former northbound Thruway roadway, which would be converted back to a local two-way street. Negotiations with Sterling Grove residents and further feedback could get that connection restored during the latter stages of Tier III analysis.

Essentially, this is Concept 4A from the Tier 1 studies, with some minor tweaking. Other than the changes around Sterling Grove and St. Genevieve, and the addition of the elevated portion shadowing Chestnut Street, it's pretty much status quo.



----------------------------------------------------------------------------------


2) Concept 4-2:  Elevated Mainline with Evangeline "Grand Boulevard"


This concept is basically the same as 4-1 but with one important exception: the Evangeline Thruway one-way couplet is replaced with a tighter "urban boulevard" taking up the southbound roadway's ROW and just to its west. The northbound Thruway in its entirity is downgraded to a two-way local street. (Clay & Magnolia Streets used this ROW before they were taken by the Thruway.) The complimentary Tier 1 proposed refinement concept was Concept 4D.

Original Refinement Concept 4D, which served as the
genesis for Concept 4-2

The freeway would be pretty much offset by one block in the downtown core area from the Thruway frontage system (whether a couplet or a boulevard); and, as I said, Chestnut Street would remain open but would be shadowed by the open freeway structure. Full access underneath the freeway would be retained. The same option for higher vertical clearance (30' instead of 22') would exist for Concept 4-2 as it would for 4-1, as would the same revisions for access for Sterling Grove.

Section of I-49 Connector Elevated Option near Sterling Grove
Historical District (Concept 4-2, with Boulevard)




-----------------------------------------------------------------------------


3) Concept 6-1: Semi-Depressed Mainline with Open Trench



This proposal is an improvement on Concept 6A in the Tier 1 study, with refinements and adjustments developed through feedback with the Evangeline Corridor Initiative group. Its main feature consists of dropping the Connector freeway mainline 10 to 12 feet below ground level, while also allowing an additional 10-12' of vertical clearance space above ground level. This would meet the DOTD standards for 20' of vertical space for freeway vehicles. Important cross streets would be elevated over the freeway via bridge structures.

Original Refinement Concept 6A (Semi-Depressed with
Open Trench); the genesis for Tier 2 Option 6-1

One interesting variation that was added since Tier 1 was the realignment of the southbound Evangeline Thruway roadway south of Johnston Street to pass over the mainline before Taft Street in order to align itself correctly with the southbound frontage road near Pinhook Road. This realignment requires a similar realignment of Taft Street to pass over the freeway, shifting its connection with the northbound Thruway roadway from Fourteenth Street to Thirteenth Street. Also, Fifteenth and Sixteenth Street would be severed at the Thruway to allow for the south connection ramps to slope properly.

Profile of Semi-Depressed Open Trench structure

The same evolution of the Thruway into a semi-boulevard from Jefferson to Simcoe, then to a parallel frontage road system north of there, would exist as with the Elevated option. However, the access for the Sterling Grove and Ballard Addition neighborhoods would be radically different with the Partially Depressed option due to the needed transition of the mainline from depressed to elevated to cross the Louisiana & Delta Railroad (L&D RR) spur line. Mudd Avenue would have to be completely severed across the freeway, and would be connected only with the frontage roads with no access between them. Chestnut Street would be totally wiped out, of course; so access for Simcoe would have to be switched to North Grant Street to access Second Street to cross the freeway and get to the east side. (Second and Third Streets would become autonomous two-way streets rather than a one-way couplet in this option.) Simcoe on its eastern flank would be diverted into the Dudley Avenue ROW and then turned back onto Greig Street with no connection at all to the southbound frontage road. Bellot and Tissington Streets would be the only means of cross-street access north of Second Street for Sterling Grove and Ballard Addition up to the L&D RR crossing.

Closeup view of cross-street access changes near
Sterling Grove Historic District from
Concept 6-1 (Semi-Depressed Open Trench)
But the rubber starts to really hit the road with the Semi-Depressed option (and Cut-and-Cover option as well....more on that later) with the downtown major cross street crossings and how they cross the BNSF railroad. The original Concept 6A proposal had Jefferson, Sixth, and Johnston Streets all grade separated over both the freeway and the rail line. That created some issues with the cross street railroad bridges extending past Cypress Street on the west side and disabling it as an access street; as well as issues with Johnston Street's intersection with Cypress Street and Garfield Street, which sets the boundary for the Freetown-Port Rico neighborhood. That's a major issue, considering that F-PR was recently made an Historical District with all the protections included.

Original concept for Tier I Enhancement Option 6A
(Semi-Depressed Mainline) showing grade-separated
overpasses of BNSF RR at Jefferson, Third, &
Johnston streets

The original 6A, as seen in the above graphic, used the original curvature of the 2003 ROD Selected Alternative, bringing the freeway close to the BNSF rail line near Johnston Street. The ECI folks, in their Charrette presentations, proposed the idea that if the curvature of the freeway mainline was "flattened" to push the apex of freeway curvature 150 feet eastbound away from the railroad, there would be enough space that the cross streets would return to ground level to cross the rail line at grade. The general idea for the ECI proposal was to have 50-100 feet of slope on either side of a 150' mainline ROW, raised 18' above ground level, and returning to existing level before the rail line to the west and the existing southbound Evangeline Thruway to the east. (More on why that idea fell apart for the Surface Tunnel option later on.) The original ECI Covered Mainline proposal for the downtown segment is illustrated below:


Evangeline Corridor Initiative's original concept
for Semi-Depressed/Cut-and-Cover "Surface Tunnel";
including "flattening the curve" of mainline
& shifting Evangeline Thruway frontage roads
to directly above/flanking covered freeway (from 10-27-16
Charrette Report)
DOTD and the Design Team, upon further study, found and reported that the concept of returning the cross streets to existing grade at the BNSF RR crossings would marginally work with the crossings at Second, Third, Jefferson, and Sixth streets. While those roadways could be returned to ground level in time to cross the BNSF/UP railroad at grade, there would be some issues with the slope of grade (nearly 7%) approaching the railroad crossings, especially for high profile vehicles. It was, though, technically feasible. Note that this option replaces the existing Jefferson Street underpass of the BNSF rail line with an at-grade crossing....for obvious reasons.

Overview of proposed Semi-Depressed overpasses of
Second, Third, Jefferson, and Sixth streets; with return
to level-grade BNSF RR crossings


Profile of Semi-Depressed option overpass of Third Street
(would also apply to Second, Jefferson, and Sixth)

Semi-Depressed (Open Trench)
cross street gradient profiles for
Downtown section

Such was not the case, unfortunately, for the Johnston Street crossing. The studies found that there simply wasn't enough space between the depressed freeway ROW and the railroad to allow for a safe return to grade to provide a grade level crossing. 

Original profile of Johnston Street overpass of Semi-Depressed
option returning to level grade to cross BNSF RR (rejected
due to insufficient space)
Thusly, the only alternative for Johnston Street was to elevate it in order to cross over the railroad. And that's where everything starts to fall apart. For starters, the required 23.5' clearance over the BNSF rail line would be much higher than the clearance needed over the Semi-Depressed freeway ROW. Most important, though, is that the overpass would require an excessively steep gradient to the west of the railroad if the idea was to return Johnston to grade near the Cypress Street/Garfield Street intersection. That was important because Johnston runs right through the Freetown-Port Rico neighborhood, which was recently endowed with Historical District status, giving it special protection against any intrusion upon it. Johnston Street is also the main arterial to the campus of University of Louisiana at Lafayette, and ultimately serves as the hurricane evacuation route for Vermilion Parish. You really don't want hurricane evacuation traffic having to traverse a 9% grade.

Original Johnston St. BNSF RR overpass profile with Semi-
Depressed option to avoid penetrating Freetown-Port Rico
Historic Distric
t
An alternative that was proposed to mitigate that situation was to raise Johnston Street and extend the structure to meet level grade at Vermilion Street to produce an acceptable gradient of 4%. That would not only require elevating the Garfield Street intersection nearly 12' above ground and severing Cypress Street; but also elevating Lincoln Street's intersection as well. The resulting penetration using Johnston Street would be a serious encroachment of the Freetown-Port Rico Historical District, bringing the full wrath of Section 4(f) and Section 106 violations. Nevertheless, the proposal here does include the elevated and separated Johnston Street overpass with the extended gradient.


Johnston St. profile for Semi-Depressed option
revised for sufficient gradient profile; note serious penetration
of FTPRHD due to need to elevate Garfield & Lincoln
streets.


Vertical view of intrusion of revised Johnston
St./BNSF RR overpass for Semi-Depressed
Open Trench option into Freetown-Port Rico
Historic District

You can notice also how the intersection of Johnston Street and the southbound Evangeline Thruway/frontage road has to be elevated on fill to meet the profile of the railroad overpass.

The Semi-Depressed alternative would also have some very severe ramifications for the neighborhoods surrounding the Sterling Grove Historical District as well. While the SGHD would not be impacted directly with any ROW takings with this or any other of the proposed concepts (same with the original 2003 ROD Selected Alternative), there would be some very nasty indirect impacts.

For starters, the Evangeline Thruway between the L&D RR rail spur crossing and Jefferson Street would have to be totally rebuilt and raised on either fill or structure to adapt to the standard vertical clearances required for the 10' depressed mainline. This would mean the Thruway and cross streets would have to be raised as much as 8 to 10 feet, and the actual crossing of the mainline would require as much as a 19 foot vertical clearance. While the northbound Thruway roadway would be shifted westward further away from the SGHD (and especially Saint Genevieve Catholic Church and School, which directly fronts the original northbound Thruway roadway), the raised height would still introduce at least a strong visual impact.

Semi-Depressed Open Trench cross street
access changes for Sterling Grove/Simcoe/
Second/Third/Jefferson area


Roadway vertical profile heights for Semi-Depressed
Open Trench option (values are above ground level)

Profile gradients of cross streets & frontage system for
Semi-Depressed Open Trench option

Then, there is the severing of Mudd Avenue at its intersection with the Thruway frontage roads. Due to the need to elevate the southbound roadway to cross over the mainline, Mudd on the west side is "teed" (terminated at a T intersection) at the southbound Thruway, while its east side going through the SGHD is similarly "teed" with the realigned northbound Thruway frontage road. No access across the freeway is possible there due to the vertical clearance requirements for the mainline. Considering that Mudd Avenue is an important arterial that also carries US 90 off of the Thruway, that's an important issue. 

Severage of Mudd Avenue due to Semi-Depressed Open Trench
option


The local cross streets from Goldman to Tissington up to the rail spur are kept open underneath the mainline (where it transitions to an elevated facility to cross the rail spur) to allow for cross access. The elevation of so many cross streets would require far more displacements and loss of access for residents, causing much more disruption for those neighborhoods.

The same would also go for the segment near Taft/Fourteenth streets, because of the realignment of Taft Street to connect with Thirteenth rather than Fourteenth, and the subsequent severing of Fourteenth, Fifteenth, and Sixteenth streets to accomodate the south connection ramps and the raised grades for the southbound roadway to pass over the mainline and connect with Taft.

Treatment of cross street access with
Semi-Depressed Open Trench option
near Taft St./Pinhook Rd. area

--------------------------------------------------------------------------------


4) Concept 6-2: Semi-Depressed "Cut-and-Cover" Mainline



This concept originally evolved out of Concept 6E of the earlier Design Team Concept Refinements. The original thought was that perhaps if both the railroad and the freeway mainline were shifted east a bit, the overpasses would remove the impact of at-grade rail crossings. One look at the implications of derailments of the railroad within the tunnel, as well as the impacts to access downtown, was enough to render that concept as impractical.

Original Refinement Concept 6E, which served as the foundation
for both the ECI Semi-Depressed Covered Mainline proposal
and the ultimate Tier II Concept 6-2 "Cut-and-Cover" option

However.....the Evangeline Corridor Initiative group (aka the "TIGER Team" due to the Department of Transportation grant it was bestowed upon to study integrating the Connector freeway into the community better) seized upon the burnt ashes of Concept 6E to develop their own alternative which they though could serve the same goals better. The resulting "Surface Tunnel" proposal eliminated the overpasses altogether and pushed the railroad centerline back to its existing ROW, creating enough space between the freeway ROW and the railroad to allow all the cross streets to return to grade.

Evangeline Corridor Initiative's "Partially Depressed
and Covered Mainline" proposal

It certainly looked more than good on graphics, and it was enough for LADOTD to allow that concept to get more detailed vetting in the Tier II process. Unfortunately, the same problems and issues that affect the Semi-Depressed open trench also dissuade the Cut-and-Cover option as well...and then some.

It should be noted that the ECI propsal extended the capped/tunneled section north to include a total reconnection of Mudd Avenue, and allowed for the extension of some more local streets between Johnston and Taft streets for better connectivity. Apparently, DOTD found those to be impractical, because they don't make their final Cut-and-Cover proposal. The cap remains set between Second Street and Taft Street, with the remainder of the mainline open-trenched.

Profile of Cut-and-Cover Tunnel structure

The same issues involving the downtown cross-street crossings with the Semi-Depressed open trench also exist with the Cut-and-Cover tunnel...but with the additional need of even higher vertical clearances to accommodate the cap. The result for the minor cross streets (Second, Third, Jefferson, Sixth, and Taft) is an even steeper gradient required to return the streets to grade to cross the BNSF/UP line. Even with that, the gradients are still marginally feasible (although, according to LADOTD, "not desirable"). Note also that, as with the Semi-Depressed open trench, the existing Jefferson Street underpass of the BNSF RR is removed and replaced with an at-grade crossing.

Downtown cross street gradients for
Cut-and-Cover option


Vertical profile for Cut-and-Cover Third St. Overpass
(applicable to Second, Jefferson, and Sixth streets as well)

Notice also that unlike the ECI Covered Mainline option where the cap returned to existing grade before the existing southbound Evangeline Thruway, this Cut-and-Cover option massively expands the embankment eastward to the point that the Thruway frontage roads have to be raised nearly 16 feet and straddled to meet the desired sloping profile. The ECI's proposal for their Semi-Depressed Covered Mainline was to reduce the embankment on the east side that it would return to existing level grade before the southbound Evangeline Thruway, similar to the sloping on the westbound side. Apparently, that was rejected by the LADOTD engineers as too excessive a slope; instead, the embankment extends all the way to the existing northbound Thruway roadway ROW, and even takes on area east of the Thruway between Third and Simcoe streets.

Profile of proposed Cut-and-Cover Johnston St. overpass
(showing insufficient space for return to existing grade level
for at-grade BNSF RR crossing)
The same issues that befell the Semi-Depressed Open Trench option also exist here with the Johnston Street crossing; to which the same solution of an expanded railroad overpass penetrating the Freetown-Port Rico Historic District is offered.


Proposed Cut-and-Cover Johnston St./BNSF RR overpass
based on avoiding FTPRHD penetration
(rejected due to excessively steep gradient)

Revised Cut-and-Cover Johnston St./BNSF RR overpass
adjusted for sufficient gradient
(with penetration of FTPRHD)

Overview of proposed Cut-and-Cover Johnston St./BNSF RR
overpass showing penetration of FTPRHD

The resulting gradients and roadway heights:

Summary of the cross street/frontage system gradient profile
for the Cut-and-Cover concept
Summary of profile heights of roadways/embankment above
ground level for Cut-and-Cover option
And also....the same issues with cross access for Sterling Grove exist as with the Semi-Depressed option, with the same resolutions therein.

Treatment of cross street access for Cut-and-Cover option
near Mudd Avenue/Sterling Grove/Second/Third/Jefferson
(virtually same as Semi-Depressed Open Trench)
Those issues alone would be enough to dissuade the Cut-and-Cover option....but apparently that wasn't enough for LADOTD. The Tier II Technical Memo report also gives some clear and concise detail of the potential downsides of constructing and operating the surface tunnel, as well as the high costs of maintenance and operation. There would have to be additional considerations for ventilation and egress of trapped vehicles in the event of an incident inside the tunnel. Fire suppression, lighting, and drainage would also have to be dealt with, especially in the event of a major hurricane evacuation through Lafayette. Also, due to Louisiana state law, handlers of hazardous materials would not be allowed to use the tunnel; they would be rerouted through the surface frontage road system.


----------------------------------------------------------------------------------

Conclusion: Comparing The Tier II Alternatives

All of this leads to the ultimate comparison: How do they stack up? The following two tables tells the tale.

First, the displacements and ROW that would be needed:

Displacement and ROW acquisition matrix for all Tier II concepts

As plainly seen, the two Concept 4 options would require less ROW than even Concept 1A (the original 2003 ROD Selected Alternative) due to the elimination of the two direct interchanges, and would have fewer displacements as well. 4-2 (with the boulevard) would use up slightly more takings than 4-1 (the couplet). The Semi-Depressed option (Concept 6-1) would be slightly worse than Concept 1A overall. The Cut-and-Cover option (Concept 6-2), though? Off the charts, with nearly three times the displacements and ROW needed due to the expanse of the embankment needed to cap the tunnel.

Even worse for the Cut-and-Cover option is that LADOTD could only acquire and pay for ROW for those areas used for "transportation purposes", meaning that other funding sources would have to be located for any property takings outside of the immediate ROW. That would add an additional expense for LCG outside of its otherwise full commitments.

Matrix of 4(f) and Section 106 impact
to Freetown-Port Rico and Sterling Grove Historical Districts
for all Tier II Concept proposals

This is the preliminary impact matrix to the two Historical Districts that the Connector passes near. An Memorandum of Agreement (MOA) is already binding on all parties regarding mitigation for the visual impacts of Sterling Grove Historic District of the originally approved Concept 1A/2003 ROD alternative. More than likely, that MOA will be extended and modified to fit the needs for the new alternative concepts.

It's likely that the impact will remain the same or even be sightly reduced with the two Concept 4 options, since the shift of the northbound roadway and the adjustments to the northbound connection ramps, combined with the removal of Simcoe Street, do lessen the impact to Sterling Grove greatly. Freetown-Port Rico would not be significantly affected either by the Elevated Option, save for a possible visual impact due to the height of the viaduct, especially if the higher 30' vertical clearance is chosen.

By contrast, Concepts 6-1 and 6-2 would both require the penetration of the Johnston Street overpass over the freeway and BNSF railroad -- a major penetration into the FTPRHD which would probably trigger Section 4(f) protocols for avoidance of impacts to historic properties.

Now, we get to the most important consideration: the cost.

Matrix for comparison of planning level costs for all Tier II Concept alternatives

Keep in mind that these cost estimates are only for the core section between the L&D rail spur and Pinhook Road, not for the entirity of the Connector freeway.

Finally, LADOTD made a comparison matrix rating all the Concepts they studied based on specified criteria. The results are shown below:

LADOTD Comparison Matrix for all Tier II Conceptual Alternatives
As plainly seen, the Concept 4 alternatives, due to their elevated nature, scored higher on the favorability index than the original Concept 1A/2003 ROD Selected Alternative; and both were far higher ranked than the Concept 6 alternatives. Concept 6-2 (the Cut-and-Cover concept) was universally panned for its excessive up-front costs, its high maintenance, its incompatibility with the goals of hurricane evacuation and Haz-Mat material transport, and its excessive taking of ROW and displacements as compared to the Concept 4 (Elevated) concept alternatives. Concept 6-1 (the Semi-Depressed Open Trench option) scored only less slightly worse than the Cut-and-Cover, but still got plenty of red and yellow marks.

Some advocates for the Cut-and-Cover point to the fact that while the front end costs for that option seem prohibitively expensive, the induced rewards for redeveloping the property taken near the ROW would ultimately make for a better economic return down the line. The ECI did do a study on that, claiming that there would be a $6 million a year local tax base return on overall economic development from the Semi-Depressed Covered Mainline option as opposed to the Elevated Mainline option.

Problem is, though, most people don't think so long-term, and the sticker shock of $818 million for a 1-1/2 mile tunnel will probably be more than enough for most officials to declare the Cut-and-Cover option to be a good idea that just wasn't good enough. The Semi-Depressed open trench option might be a bit cheaper, but the image of it becoming a flowing tributary of the Vermilion River after a heavy rainfall event may become etched enough in people's minds to reject that, too.

Which means that it's becoming more apparent that we are back where we were at the beginning, with an elevated I-49 Connector freeway going through the heart of Lafayette.

Unless some unforseen new environmental impact (such as the possible contamination of the former Southern Pacific Railroad rail yard, or the resolution of the Connector messing with the flight path of Runway 11-29 at Lafayette Regional Airport) was to emerge, the only remaining obstacle to the Connector's implementation will be the legal firestorm from those opponents who want to kick this project completely out of Lafayette in favor of their Teche Ridge Bypass through St. Martin Parish. I'm sure that the Concerned Citizens for Good Government and the Greater Acadiana Sierra Club are already calling their lawyers for the inevitable second lawsuit that will be filed the day after the Supplemental ROD is delivered for this current study. We'll just have to watch this unfold.

Monday, October 17, 2016

Building The Better Mousetrap: ECI, Signature Bridges, And The Surface Cover That Could Change The Game

The most fundamental question involving construction of the I-49 Lafayette Connector from the beginning has been this: Can a major six-lane freeway be built through the heart of Lafayette that can be integrated with the historic neighborhoods and downtown without wiping them off the map?

Many living in those neighborhoods, along with many advocates for New Urbanism, have said, "Oh HELL TO THE NO!!", citing the history of badly planned and executed freeways being driven through inner cities without any due planning or respect for those being razed. They have been and still are the biggest advocates for swinging I-49 around the city via a bypass, while protecting the inner neighborhoods through "road diets" and reemphasis on non-auto based transportation options.

Thankfully, that attitude is being seriously challenged by a new breed of urban planning that could change the way that urban freeways are built in these areas. And, they just might have more than a snowball's chance in Hell of executing their designs here in Lafayette.

The Evangeline Corridor Initiative (ECI) is an outgrowth of the Evangeline Thruway Redevelopment Team (ETRT), an organization founded by the Lafayette City/Parish Consolidated Government (LCG) as a go-between for redevelopment of the neighborhoods affected by the Connector freeway. The ETRT was formed under the guise of a joint agreement between LCG and the Louisiana Department of Transportation and Development (LADOTD or DOTD) to enact preliminary corridor preservation and property acquisition for the Connector project. It's main focus, however, is to attempt to successfully integrate the Connector project with the surrounding neighborhoods and downtown in a seamless and constructive fashion that promotes both Smart Growth principles and appropriate development.

In 2014, the ETRT applied for and was awarded a $500,000 grant from the US Department of Transportation through its Transportation Investment Generating Economic Recovery (TIGER) Grant program for implementing and integrating the Connector freeway project with the community of Lafayette that would be most impacted by its construction. Their now ongoing study has the goal of not only meshing the freeway with its surroundings, but also provide more direct connectivity between the neighborhoods affected through more diverse options for transport (such as bicycles and walking); as well as improve opportunities for more suitable and better scaled economic development.

To facilitate the implementation of the project, three Areas of Influence were established for the Connector freeway:

-- Area  Level I consisted of the actual right-of-way taken for the freeway facility;

-- Area Level II consisted of a 500 foot buffer zone on either side of the ROW, which would serve as a transition zone between the freeway and its surrounding neighborhoods; and

-- Area Level III consisted of the boundaries of the neighborhoods immediately impacted by the project.



ETRT's and ECI's main purpose would be to develop Area Levels II and III, and interact with DOTD and FHWA on refining Area Level I to meet their goals.

When the ECI originally announced its initial study, the assumption was that the design for the Connector would strictly follow the Selected Alternative that was approved in the 2003 Record of Decision. That alternative consisted of a mostly elevated freeway utilizing most of the Evangeline Thruway corridor, save for a segment near downtown where it would follow a gradual curve just east of the Burlington Northern Santa Fe/Union Pacific (BNSF/UP) main railroad line. Two standalone interchanges along that section with a realigned Second Street/Third Street couplet and Johnston Street would provide direct access to downtown and the neighborhoods surrounding that area; grade separated underpasses of the railroad line would prevent conflicts. Other than a brief section between Jefferson Street and Johnston Street where the mainline freeway would be elevated on embankment to account for the ramps to the two close interchanges, the mainline would be elevated for most of its entirity. Higher than usual vertical clearances (22 feet rather than the typical 16.5 feet) would be used in the segment between the Louisiana and Delta Railroad (L&DRR) spur line and Simcoe Street as part of mitigation for the visual impact to the Sterling Grove Historic District neighborhood. Also, the existing Evangeline Thruway couplet would be retained as part of a frontage road system feeding the Connector freeway and providing secondary access along with the interchanges.

Aerial profile of I-49 Lafayette Connector Selected Alternative, based on
2003 Record of Decision and 2007 Conceptual Study

However, when the Conceptual Study was revived in October of 2015, those assumptions quickly were rendered useless. There was the historical strong opposition from those who opposed building the freeway through Lafayette from the very beginning, preferring a bypass alignment to the east such as the Teche Ridge Bypass or the Lafayette Regional eXpressway (LRX) alternative to the west.

However, a different form of opposition soon emerged from downtown interests who did favor the central alignment, but begged to seriously differ on some of its details. The Lafayette Downtown Development Authority (LDDA) was particularly not so keen to some elements of the Selected Alternative; and their objections were reinforced through both the public involvement process of the main Conceptual Design Study and the initial meetings of the Evangeline Corridor Initiative through their innovative "charrette" meetings. The main objections were:

1) The two standalone interchanges with the Connector at Johnston Street and Second/Third Streets took way too much right-of-way that could be used for development, and were unnecessarily divisive for connectivity.

2) The embanked segment of the mainline between Johnston Street and the Jefferson Street underpass was too divisive, and severed an important collector (Sixth Street/Lee Avenue).

3) The Second/Third Street couplet interchange/railroad underpass potentially forced too much traffic onto Congress Street (which the couplet directly fed into), which contradicted plans for remodeling the latter as a "Complete Streets" prototype for pedestrian/bicycle access and slowing vehicle speeds. It also potentially impacted the Coburn Building, an old retail shop that had recently been approved into the National Register of Historic Buildings.

In reaction to those objections, LADOTD was induced to add a six-month period where modifications to the Selected Alternative could be proposed to address these needs. While the alignment remained the same as to not disturb the concept approved by the 2003 ROD, tweaks to the system of access were proposed, ultimately resulting in 19 design "refinement" modifications by May of 2016.

The ECI study was conceived to run parallel with and advise the DOTD study, and to provide some form of feedback for addressing the Joint Use and greenspace requirements for the freeway. Originally, the idea was that ECI would serve only to perform the development of design for Levels II and III...but as the ideas kept rolling in, it was becoming apparent that they should intervene with DOTD to offer up their own alternative designs more suitable to their goals. In the end they settled on two main concepts, both based on concepts developed by DOTD, but with their own alterations.

Elevated Mainline with Signature Bridge

Overview of Elevated Mainline with Signature Bridge
concept from Evangeline Corridor Initiative
(from ECI Draft Charette Report)
DOTD Concept 4D (Evangeline Parkway), the genesis of ECI's
Elevated Mainline with Signature Bridge design



Generally based on the Series 4 concept from DOTD, this alternative design entailed a continuous elevated structure along the length of I-49 from the Chalmette Drive crossover all the way to the Vermilion River crossing (or even the University Avenue/Surrey Street crossing). The effect would be more of a large scale land bridge crossing Lafayette, with the peak of the crossing designed as a "signature bridge" landmark that would define downtown Lafayette. Instead of direct interchanges downtown, access would be provided through direct connection "slip ramps" to a redefined Evangeline Thruway frontage system, with the slip ramps placed between the L&DRR and Mudd Avenue for north access, and between Pinhook Road and the Vermilion River crossing for south access. The Evangeline Thruway southbound roadway would be reformed as a six-lane urban boulevard for local business development; the northbound Thruway roadway would be downgraded to a two-way local street and returned to the local grid for the McComb-Veazey neighborhood. Accessibility and connectivity would be improved and restored underneath the "signature bridge" by adding additional cross streets over the BNSF/UP railroad, and restoring some one-way streets to two-way for refining the downtown grid. The space immediately under the bridge structure would be developed for public parking and green park space.



Semi-Depressed Mainline with Cover (Surface Tunnel)



This concept was actually not included in the 19 design modifications put out by DOTD, but is a modification by ECI of one that was included. Part of the Series 6 concepts, this was originally developed thanks to input from an unnamed constituent who noted that an original concept of a depressed Connector freeway was vetted and rejected in the early studies. That concept would have depressed the mainline freeway 20 feet below ground level within the median of the the entirity of the Evangeline Thruway. While it was ruled to be marginally feasible, it was rejected out of practicality and the need for I-49 as a hurricane evacuation route. The constituent suggested that maybe a partially depressed freeway would work better; and studies did confirm initially that a 10 foot drop would better allow for gravity drainage.

The Series 6 concept designs are based on dropping the elevated segments from just south of the L&DRR spur overpass to Pinhook Road down 10 feet below ground level, and adding 10 feet of vertical clearance, for a total of 20 feet. Crossing streets would then be allowed to pass over the freeway for connectivity. The first concept (6A) called for an open trench; subsequent concepts added the cover for a partially submerged tunnel effect.



The ECI Covered Semi-Depressed Mainline alternative is an adjustment to LADOTD's Concept 6E, which originally called for flattening the curve of the mainline freeway and also shifting the alignment of the BNSF/UP rail line 150 feet east of its current ROW and dropping it to the same level as the freeway. All ECI did was to return the rail line back to its current trajectory, but keep the shift of the freeway centerline so that the resulting berming over the freeway tunnel could return to existing grade prior to the rail line. This allowed all the crossing streets to retain at-grade crossings of the railroad, removing the need for overpasses.


The other striking feature of the Semi-Depressed/Covered Mainline alternative is that the Evangeline Thruway is essentially replaced altogether with an avenue/boulevard hybrid built directly on top of the tunneled mainline segment, and accessible through the same "slip ramp" connection system as the Elevated Mainline uses. The original Thruway roadways would be downgraded to local streets within the neighborhood grid. (There is an option that utilizes both the avenue on top and the boulevard on the side.)

Initially, DOTD balked at including ECI's alterations to their Series 6 options in their initial analysis, citing both the protocol of DOTD handling Area Level I and that the time for entering concept modifications had passed. Under strong pressure from LCG officials insisting that the alterations be added (as a new concept "6F"), DOTD partially relented and allowed for consideration of the ECI alterations to 6E, provided that that series passed the initial Tier I analysis...which it did by August 2016. All of the modifications under Series 4 and 6 are now currently under a more involved Tier II analysis by DOTD, which will result in the culling down to three finalist alternatives by the end of October, and a final selected and approved alternative by the end of December.

Reinventing Lafayette Gateway North...The Arc d'Willow???

Another goal of the ECI study was to find new ways of exploiting the Connector freeway to redevelop neighborhoods that had been struggling to rise economically. The Lafayette North Gateway District is one distinct example. Once a center of activity through Northgate Mall, Albertsons', and Walmart, North Lafayette along the Evangeline Thruway has suffered greatly economically, and it is accelerated by the lack of through access due to the nature of the at-grade Thruway.

The original concept for the Selected Alternative in this area was to integrate the Evangeline Thruway into the frontage road system as traditional one-way frontage roads, with a slip-ramp diamond interchange at Willow Street and underpass connections at Martin Luther King Drive/Castille Avenue and at Donlon Avenue/Walmart Drive. The Gateway Visitors Center within the median of the Thruway would be removed and relocated to make room for the Willow Street overpass/interchange.




Needless to say, the ECI folks took one look at those plans and announced: "Ummmm...nope. We can do much better than this." And this was the result:



The second most distinct feature of this refinement is the radical transformation of the Willow Street interchange. No more slip ramp diamond; now it's a huge circle interchange with the ramps from I-49 connecting directly to the circle rather than the frontage roads. The MLK/Castille and Donlon/Walmart intersections are now smaller circle/roundabouts, too, and all connected with two-way local streets fronting houses and mixed-used development. Both the Northgate Mall and Walmart properties are also transformed into mixed-use/smaller business development as well.

I did say second most distinct, right? For #1, you got to look what's inside the Willow Street Circle. Behold, behold...the Arc d' Lafayette!!


Yes, that would be a 60 foot imitation of Paris' Arc d'Triomphe straddling the Connector overpass of Willow Circle, complete with a new home for the Visitors' Center and an observation deck on top. This is what you call "thinking outside the box".

All of this may seem quite expensive and beyond the reach of funding for the Connector freeway, but considering the alternative of not completing I-49 South or having it diverted around Cypress Swamp and St. Martinville and Breaux Bridge for no benefit, I'd say that this deserves more than just a look.