bridgehankcobbs

The Raphael Semmes Bridge

Elegant, simple location for new I-10 bridge over Mobile River or Bridge Gargantua?

By Chip Drago

Mobile Bay Times

On first encountering H. Stewart "Hank" Cobb, Jr., a short, round 77-year-old man who resembles a cross between Winnie-the-Pooh and Owl, one wouldn't necessarily muse, "I bet he taught Jimmy Buffett to sail," or even that Cobb could resolve all the conflicts spicing the process of selecting the route for a proposed new I-10 bridge over Mobile River near downtown.

But oddities and surprises come in all ages, shapes and sizes.

Cobb is an Eagle Scout, Silver Beaver, Wood Badge, Order of the Arrow, with 52 years as a Scouter and 42,000 miles of ocean racing sailing.

"I taught Jimmy Buffett to sail when I was a Sea Scout Skipper," recalls Cobb of days gone by with the youthful native son of a son of a sailor.

And he remarks, not in the same breath, but also: "There is an elegant and simple solution to the location of the I-10 downriver bridge over Mobile River."

Cobb analyzed 20-40, multi-million dollar contractor proposals a year during a 25-year career as a contracting officer for the federal government. He is inquisitive. He likes problems. Without problems, he would have no opportunity to think outside the box of pedestrian fixes where an untethered mind may capture an "elegant, simple" solution flitting about in a field unbothered by the experts.

One suspects Cobb relishes those 'shazam' moments when the masses clap their collective hand to forehead, exclaiming 'why didn't I think of that?'

Could such be the case in the hubbub over the proposed new I-10 bridge intended to relieve the bottleneck choking the cross-country artery at the Wallace Tunnel in Mobile?

Traffic engineers say, 'let's wring out this kink.' A to B quickly and efficiently.

But in-the-way shipyards and other waterfront interests say 'whoa, do you want to foul the lifeblood of the local economy?'

And what of the city's new award-winning cruise terminal, home to the wildly successful Carnival Cruise Lines' Holiday cruise ship, perhaps just a starter in Mobile's much bigger splash as a cruise port? Should a mammoth bridge footing squash that promise?

Historic preservationists, downtown redevelopment proponents, Down-the-Bay residents all stand alarmed in the shadow of the three proposed routes for the 200-foot-plus high new bridge.

Into the fray strides Cobb.

"Where is this mysterious, elegant and simple location ...?" he asks. "The answer is that it is hidden -- hidden in plain sight!"

Grant Cobb the stage: "From the I-65 merge with I-10 travel straight-line easterly to the Broad Street overpass and (on the straight ahead rising approach ramp) go up and over the McDuffie Coal Terminal, cross the bridge over the tip edge of the mouth of Mobile River, come down over Pinto Island south of the Battleship Alabama and merge into the new Bayway in the center of the Bay."

In Cobb's lexicon, "simple, easy and obvious" should not be construed necessarily with small or inexpensive.

The river clearance under the bridge would be a minimum of 360 feet at neap tide, and the roadbed at 375 feet, according to Cobb's proposal. Support piers for such a structure would be as high as 600 feet, according to local engineers. The Cooper River Bridge in Charleston, SC has towers rising 575 feet high, although the roadbed's vertical clearance above the median high tide mark is only 200 feet.

At a cost of $800 million-$1 billion, the bridge would be 10-25 percent more expensive than the mid-river routes, Cobb estimated.

Accepting as official the dismissal of a northern route using the Cochrane-AfricaTown Bridge, Cobb posits a picturesque Raphael Semmes Bridge soaring majestically above any of the three remaining prospective routes/bridges that engineers have left on the table that once held fully 14 alternate routes.

"Fly over this site and it is obvious it should be the location for the new bridge," states Cobb.

The straight east/west crossing would feature three-mile approach ramps with a gentle seven to nine percent slope enabling fully-loaded cross-country trucks to maintain speed while crossing the bridge, according to Cobb.

No more trucks spilled at the hairpin eastbound entry to the Wallace Tunnel, clogging traffic for hours, not to mention injury and loss of life and property.

Because the Raphael Semmes Bridge is so much farther south of downtown, the perspective on its size and scale changes for the better. A monster looming over a trembling downtown becomes an awesome, inspiring monument at a certain distance.

Architects, engineers and bridge designers would have "much greater freedom and latitude to design a strong, earthquake-resistant bridge of great beauty comparable to the Golden Gate or the Verrazano Narrows Bridges," said Cobb.

"Shipping and shipbuilding interests will love this location, the historic preservationists will love it, and the city fathers will love it as a magnificent backdrop to our new downtown Mobile city skyline," Cobb said.

Other advantages in Cobb's view include:

No dangerous sharp curves or compound curves or S curves;

No entrance merges or exits all the way from horizontal east to horizontal west;

No, "repeat no," vehicle exhaust miasma/smog ("remember carbon monoxide sinks") blown from mid-river bridge crossing approach ramps enveloping existing urban renewal residential areas;

Limited need to acquire expensive right-of-way since most of the necessary land is vacant today;

No need to bring any of the long distance, cross-country, state-to-state traffic close to downtown Mobile.

And, says Cobb, that's not all; there's more, much more and he will tell you about it later.

But first let's talk about the weather -- earthquakes, tsunamis, hurricanes and global warming.

Mobile Bay, Cobb points out, is sandwiched between two earthquake zones:

The first zone is the tectonic plates shifting on the floor of the Gulf of Mexico (a 6.8 Richter Scale quake 300 miles south of Mobile in 2006, and quakes with epicenters in Atmore and Brewton in 2005), and

The second zone is the radius around the New Madrid fault line extending south through Tennessee, with branches in Alabama and across to Charleston.

The New Madrid, Missouri, Great Earthquake in 1811 (8.6 on the Richter scale) is the strongest recorded earthquake in the contiguous 48 states with severe damage for a radius of 600 kilometers (more than 500 miles) and the Charleston earthquake in 1883 was a 6.6 Richter, Cobb said. Scientists predict the next earthquake along the New Madrid fault line, possibly nearer Mobile, to already be 100 years overdue, he noted. Thus, a major quake could happen any time in the coming 200 years and set off a 20- to 50-foot high tsunami in north Mobile Bay, according to Cobb.

Hurricanes Ivan, Georges and Katrina sent 20-foot surges up Mobile Bay and Mobile River. Polar Ice Melt is expected to produce a 20-foot sea level rise around the world during the next 200 years, Cobb noted, citing National Geographic magazine as his source.

"Because of the pull of gravity from the sun, the sea level rise will be higher in the equatorial belt meaning Mobile (at 30 degrees north latitude) would likely experience a 25- to 30-foot sea level rise in the summer season when we are closer to the sun," Cobb stated.

"Any two of these events at the same time on top of a storm tide would mean that the Bridge would have to be 40 to 80 feet higher than presently planned to allow Mobile Harbor and Tennessee-Tombigbee river traffic to continue to move safely under the bridge," Cobb said.

"Cochrane Bridge is not high enough for Texas Tower drilling rigs to move under it, as Katrina proved," he continued. "In the coming 200 years, 12- to 15-deck cruise ships will move under the downriver bridge for passengers or drydock."

Therefore, said Cobb, a 360-foot clearance should be the minimum height for the new Raphael Semmes Bridge.

There exists adequate space, land and distance for gentle approach ramps east and west to accommodate a bridge 360 feet high, he added.

Other advantages, as Cobb promised, include:

The potential for an east-bound 12-lane toll plaza (no west-bound toll collected) on "the copious land available in the I-10/Dauphin Island Parkway interchange, the I-10/Michigan Avenue interchange, the junkyard at the Navco Road overpass, or on the vacant land southeast of the I-10 Broad Street overpass, thus there would be no storm-vulnerable, expensive-to-build toll plaza in the middle of the Bay;

The bridge abutments for the east end of the bridge would be built on the clean vacant land at the south end of Pinto Island where Cheniere originally planned to build an LNG receiving facility, thus the bridge east-side approach ramp would avoid a necessity for Federal Highway Administration to clean up the contaminated-with-toxic-metals river dredge spoil area between Battleship Park and Atlantic Marine, saving FHA $50-$100 million in clean-up costs that would be required if a mid-river bridge crossing option was selected;

The short distance that the new Bayway (raised to 40-plus feet above neap tide and widened to eight through lanes) from the Daphne shoreline to the end of the east-side approach ramp would be reduced in length by more than 60-percent, thus saving FHA $40 to $60 million over existing mid-river crossing options;

The bridge abutments could be built well back (200 to 300 feet back) from the river shoreline on both sides, thus facilitating construction, with abutments adequately anchored to eliminate earthquake shaking and prevent future ship-barge/bridge-abutments collisions;

The existing I-10/Wallace Tunnels/Bayway route can be renumbered I-210 and restricted to local traffic or two-axle passenger vehicles only;

The new Raphael Semmes Bridge would be five miles east and much lower than the flight path for the north-south runway at Brookley and ten or more miles north of the flight path serving the southeast-northwest 12,500 foot main runway at Brookley Field.

A seven-degree approach slope would allow a parallel railroad bridge to be built alongside the new Raphael Semmes Bridge to serve Choctaw Terminal, central Baldwin County and points east, and create a double-back route possibility from the east to serve Alabama Port expansion on Blakeley Island;

I-10 traffic is variously predicted to triple or quadruple in the coming 50 years. With enough lanes, or planned expansion opportunities built in, the new Raphael Semmes Bridge in this downriver location could easily handle future traffic capacity challenges;

"This list of suggestions answers all the realistic objections -- except cost -- that I can remember to the mid-river, close to downtown, bridge crossing," said Cobb.

Cobb has only one request should his proposal come to pass.

"If the new Raphael Semmes Bridge is located, designed and built as I have suggested, it will take seven or eight years," he said. "I will be 85-years-old when it is completed and opened, and I would very much like to be invited to be one of the people to participate in cutting the ribbon at the opening ceremony."