BACKGROUND

A meeting was held in Charleston, South Carolina, to develop a project plan for measuring the vertical clearance for the Cooper River Bridges, known as the Grace Memorial (older bridge) and the Silas Pearman (newer bridge). This measurement is critical to ensuring safe navigation for the Port of Charleston.

This is the first step towards implementation of real-time, using GPS, sensors that will determine the maximum height of a vessel at the lowest point of the Cooper River Bridges. This follows NOAA goal to Promote Safe Navigation. A timely response is extremely critical to this problem for navigation since a ship recently struck the Silas Pearman bridge.

Preliminary meetings were held in Charleston, South Carolina, with the following in attendance:

1. Captain Russell Woodill, Maritime Association Port of Charleston.
2. Commander Bob Bennett, Marine Safety Office, U.S.C.G.
3. Mr. J. Wesley Timmerman, South Carolina Department of Transportation
4. Commander John Wilder, NOAA/ NOS/CS
5. Mr. David Zilkoski, NOAA/NOS/NGS
6. Mr. Jim Dixon, NOAA/NOS/OPSD.

During the meeting the following scenarios were discussed:

1. Two GPS receivers on the older bridge for 1 week
2. One receiver on the newer bridge for 1 week
3. Threes GPS receivers on the older bridge for 30 days
4. One GPS receivers at the tidal station for 37 days

It was finally decided that two GPS receivers would be on the newer bridge, one receiver on the old bridge, and one receiver at the pilot house.

Preliminary schedule is as follows:

1. SCDOT provide NGS drawing of bridges by 11/30/1998 - DONE
2. NGS/OPSD/SCDOT conduct full site reconnaissance by 12/11/1998 - DONE
3. Finalize project plans NGS/OPSD by 01/15/99 - DONE
4. Conduct Static Measurements during 01/15/99 to 02/28/99 changed to 02/04/99- 03/05/99
5. One sensor to remain in place 03/05/99 to 03/31/2000

The following will do the following for the project:

1. NGS and OPSD will do the necessary field work.
2. SCDOT will provide guidance and or perform the climbing on the bridge.
3. SCDOT will provide for the electrical power required on the bridges.
4. NOS will provide the DGPS and associated radios and computer equipment.
5. Pilot Association pilot house will provide space, AC power, telephone service and security for the base station.
6. Charleston Center's will provide the T-1 communication lines.

1. Position the bridges observing with three different receivers on the bridges, one at the pilot house and a CORS site (CHA1). Observations will be 1 week to 30 days. (CORS plus 4 receivers)
2. Perform two one hour (min) sessions observing three NAVD88 bench marks plus one primary tidal station (bench mark). One session will be in AM of day 1 and PM of day 2. (CORS plus 4 receivers at min., working on getting one more receiver to co-observe at the pilot house at the same time.)
3. Leveling observations to determine the height of the bottom of the bridge to each of the antenna mounts.
4. Do a psuedo-kinematic survey of at least three NAVD88 bench mark between the primary tidal station and another bench mark from phase 2. (Note this will be done only if time permits.)

1. All GPS observations will be blue booked and adjusted and loaded into the NGS data base.
2. All leveling observations will be blue booked and loaded into the NGS data base.
3. There will be a relationship between the ellipsoid heights and water level values.
4. It will be training for OPSD (FOB & REB) groups on planning, observing, processing and doing adjustments of GPS-derived ellipsoid and orthometric height projects to 2 cm and 5cm.
5. There will be GPS-derived height for the bottom of the bridge and leveled height of the bottom of the bridge to compare results.

The following responsibililies and assignments were determined during the meeting held on January 7, 1999 at NGS with the following people present, from NGS; Edward Carlson, Bill Rindal, David Crockett, David Crump, Audie Murray, and David Zilkoski, from OPSD; Jeff Oyler, Brad Winn, Brooks Widder.:

1. Determining the height of the bridge, bottom to antenna mount - Murray, Rindal, Crockett
2. GPS observations - Carlson, Oyler, Wynn, Widder
3. Installing the GPS equipment and gathering the GPS data on the bridges and the pilot house - Crump, Maron
4. Any leveling needed to be done - Crockett, Murray, Rindal, Carlson
5. All vertical observations are blue booked, adjusted and loaded into the NGS data base - Murray, Crockett
6. All GPS observations are processed, adjusted, blue booked and loaded into the NGS data base - Oyler, Carlson
7. Project coordinators - Carlson, Oyler

Jeff Oyler - will contact Cmdr. Wilder about contacting the Charleston Bridge DOT about the following:

1. lane closures on the two bridges, Wednesday, Feb 3 - southern most lane on new bridge; Thursday, Feb 4 - northern most lane on the old bridge; Friday, Feb 5- southern most lane on new bridge (if needed); Saturday, Feb 6 - northern most lane on old bridge (if needed).
2. Three days to install the GPS receivers on the two bridges after the trig leveling and bench mark GPS work is completed .
3. Supplying continuous 110 VAC power at the centerspan for the three receivers.

Brad Wynn - will find about lodging for the project. Design and procure bridge and pilot house antenna mounts.

Dave Crump - will let Edward Carlson know how much data can be stored on the FLASH CARD used in the receivers. Find two additional Ashtech antennas and one receiver which can be used for this project.

Audie Murray and Bill Rindal - will practice and determine the best method/procedures for determining the elevation at each antenna mounting plate, for profiling the span and methods to compute the elevation for the bottom of each bridge.

David Crockett - will investigate the bench marks which will be used for leveling to the new bench mark which will have to be set.

Dave Crump, Edward Carlson, Ernie Maron - will test each receiver at NIST.

Edward Carlson and David Crockett - will transport all the FOB GPS equipment to Charleston.
 
 

 
 

	AM	PM
Monday  February 1, 1999	Travel	Travel
Tuesday February 2, 1999	Finish RECON + set marks (Crockett, Carlson, Oyler, Widder)  Set mounting plates on new bridge and install antenna cables (Crump, Murray, Rindal,Wynn) Set up base station at pilot house (Marion)	Static GPS observations on bench marks (Crockett, Carlson, Oyler, Widder) Mount antenna and cables at PILOT house (Crump, Murray, Rindal, Wynn) Set up base station at pilot house (Marion)
Wednesday February 3, 1999	Static GPS observations on BMs (Wynn, Carlson, Oyler, Widder) Trig leveling on new bridge (Crump, Murray, Rindal, Wynn) Set up base station at pilot house (Marion)	Psuedo-kinematic GPS on BMs around the tidal station (Wynn, Carlson, Oyler, Widder) Trig leveling on new bridge (Crockett, Murray, Rindal, Crump) Set up receivers on the new bridge (Marion, Crump, plus others)
Thursday February 4, 1999	Level new bench marks  (Crockett, Carlson, Oyler, Widder) Trig leveling on old bridge (Crump, Murray, Rindal, Crockett)	Training on processing GPS data (Carlson, Oyler, Wynn, Widder ) Trig leveling on old bridge (Crump, Murray, Rindal, Crockett) Set up receiver on the old bridge ( Crump, plus others)
Friday  February 5, 1999 (See note # 2)	Psuedo-kinematic GPS on BMs around the tidal station (Carlson, Oyler, Widder, Wynn) Trig leveling on new bridge (Crump, Murray, Rindal, Crockett)	Training on processing GPS data (Carlson, Oyler, Wynn, Widder ) Trig leveling on new bridge (Crump, Murray, Rindal, Crockett) Set up receivers on the new bridge (Crump, plus others)
Saturday February 6, 1999 (See note # 2)	Training on processing GPS data (Carlson, Oyler, Wynn, Widder ) Trig leveling on old bridge (Crump, Murray, Rindal, Crockett)	Training on processing GPS data (Carlson, Oyler, Wynn, Widder ) Trig leveling on new bridge (Crump, Murray, Rindal, Crockett) Set up receiver on the old bridge  (Crump, plus others)
Sunday February 7, 1999	Travel	Travel

NOTE 1 - Ernie Marion could return on Thursday morning.

NOTE 2 - When the trig leveling to determine the height of the bridge, bottom to the antenna mount, for all the antenna mounts on both bridges and the static GPS observations on the BMs is completed which could be as early as Friday or Saturday morning then Carlson, Crockett, Murray, and Rindal will travel home. Remember trig leveling could take longer than scheduled above because of weather conditions or the DOT which means that Rindal, Murray and Crump would have stay longer in Charleston.