|December 31, 2003
I sent out the below e-mail yesterday but forgot to cover a few other important things pertaining to matter.
1. When you review the Bridge Railing Manual, you're going to see a few rails that allow its height to be decreased and you're going to see several other rails for which the min. height has not yet been established. Even if a rail's height can be decreased, you need to mill-off the existing ACP before placing the new mat. For the rails that don't have an established min. height, you should assume that the allowed decrease is zero.
2. I stated that if the MBGF is being upgraded but not the bridge rail, a custom bridge rail to guard fence transition may be needed. The details for the rail to rail attachment will depend on the type of the existing bridge rail but no matter how it's done, it won't meet the present requirements so if you have this situation, you'd be better off getting exception/waiver approval to leave both the existing bridge rail and the existing transition to the existing guard fence.
3. The Bridge Railing Manual states that the FHWA Policy is for the National Highway System (NHS) but our Austin TxDOT folks decided to apply the same rules to ALL roadways so it doesn't matter if your project is on an Interstate or an FM.
4. The Bridge Railing Manual allows an ACP taper as a way to maintain the rail height. The Manual sates " At least 10 feet of flat (1 V : 10 H or flatter) pavement must exist in front of the railing." This doesn't mean that the taper has to be 10 ft. long because the X-slope of a rdwy is flatter than a 10:1 so the pavement prior to the taper will be flatter. The ACP taper length will be whatever it takes to get the 10:1 such as a min. of 20 inches long for a 2 inch mat. When I said that David said a 10:1 taper is doable, I didn't mean for it to appear that he decided this is an acceptable way to treat the rail height. All David said was that the flat taper can be done with a taper tool attached to the end of the lay-down machine. Maybe some hand racking will have to done so it won't look as good as the rest of the mat but it's cheaper and faster than having to do something to the rail.
5. The Manual states to call the Bridge Division for assistance but if you have a question or need help with a unique situation, please call Jon or myself and we'll contact Austin if needed.
OBSOLETE BRIDGE RAIL
A. On all projects developed under 3R or 4R design criteria, upgrade of obsolete bridge rail, approaching guard fence & bridge rail transitions is required if the bridge is within the limits of the project. This work MUST be done unless:
1. Bridge rails conforming to NCHRP 230 (crash test requirement prior to the present NCHRP 350) do not need to be upgraded. Look at the Bridge Railing Manual and/or Contact Jon Kilgore to find out what the existing rail on your project meets. However, if you are going to replace the rail, the new rail must meet the 350 crash requirements.
2. You process and get Design Exception (for rdwy's W/ an ADT > 1500) or Design Waiver (for rdwy's W/ an ADT of < 1500) approval. An acceptable reason for requesting an Exception or Waiver is that the bridge is already scheduled for rehabilitation provided the rehab. is going to take place within a reasonable amount of time (+/- one year). Stating that bridge rail work is not part of the project's scope or that this work cost too much are NOT acceptable reasons so make sure to include the cost for this work in your preliminary estimate. If MBGF is being upgraded but not the bridge rail, you might need a special transition section between the two rails. If so, contact Jon for assistance.
B. Obsolete bridge rails are NOT required to be upgraded by Preventive Maintenance or 2R projects.
BRIDGE RAIL HEIGHT
Regardless of the type of project, the height of bridge rails can NOT be decreased below the min. needed for satisfactory performance and for some rails the allowed decrease is ZERO. Look in the Bridge Railing Manual or call Jon to find out the rail height tolerance. For the rails with zero height tolerance, you can NOT place an ACP overlay next to the rail and stopping the overlay a few inches away from the rail or placing a steep taper down to the rail is NOT acceptable. And, just removing all previous overlays then placing the new mat doesn't meet the requirement because the rail will still not be at the required height due to the new mat. To meet the rail height requirement for the ones that have a zero tolerance, you can:
1. Inspect the slab and if it is in good shape, do NOT overlay it. Just because a bridge is within the overlay limits of a project doesn't mean you have to overlay it. This should be your no. 1 option.
2. If a slab has a previous overlay or the slab needs to be overlaid (for whatever reason), first consider a seal coat and not ACP. If the traffic volumes are too high for just a seal, a 10:1 taper of the ACP down to and just short of the bottom of the rail is acceptable and according to David Kopp, a 10:1 ACP taper is doable. If you're going to use this option, first make sure the taper doesn't end up trapping surface runoff then make sure the required taper is shown in the plans.
3. Upgrade the rail to a type that meets the present crash test requirements and has a height tolerance of 2 to 3 inches or retrofit more height onto the top of the existing rail. Needless to say, this option is the most expensive but if the existing rail is in need of work and/or this rdwy. is not going to be addressed again for several years, you might want to do this work (if Clay can afford to give you more $'s).
At PS&E time, unless it's shown in the plans, we have no way of knowing what type of rail is on the bridges so it's up to your designers to remember to meet the above requirements. Please forward this e-mail to your in-house and consultant designers.
December 30, 2002
1. When we started sending our plans to the TDLR in the late 90's, TDLR said everything new MUST meet TAS but where new construction tied to existing, the existing SHOULD meet but it was NOT required. TDLR is now saying that the existing has to meet TAS 4.1.6 (1) (c) which states " If alterations of single elements, when considered together, amount to an alteration of a room or space in a building or facility, the entire space shall be made accessible."
What led to this was a project that was constructing new sidewalks either side of existing driveways within the project but was not reconstructing the driveways. The TDLR's review said the sidewalk through these driveways has to meet TAS. So, the designer will have to determine if existing pedestrian elements (sidewalks, driveways, curb ramps, crosswalks, etc.) meet TAS and if they don't, the existing elements have to be reconstructed at the same time as the new sidewalk.
2. When a pedestrian goes across a street, the crosswalk is considered a continuation of the sidewalk so the pavement of the street (main street or side street) has to have a max. cross slope of 2%. If the project is 100% sidewalk work, we can probably get a TAS Variance approved to leave the intersection pavement as-is. However, for a roadway project that has proposed work in the intersection due to geometric changes on the main or side street, it'll be difficult to get a Variance approved. If for safety reasons, we do not want pedestrians crossing the main street at all intersections, we don't have to provide the 2% but at signalized intersections with ped. heads and marked crosswalks in most directions, the pavement on the crosswalk has to be 2% on both the main street and the side street so this has to be taken into account on the roadway's profile.
3. If the cross slope of the street is not 2%, the cross slope of the curb ramp will also not be 2% so we end up not meeting two TAS requirements and the more things we don't meet, the tougher it is to get Variance approval.
During the final inspection, the inspector is checking the crossslope of ramps and crosswalks at intersections with crosswalks. Don't wait until final inspection time, process an ADA/TAS Design Variance as soon as you know that a pedestrian element isn't going to meet.
December 30, 2002
Some revisions were made to the subject Notes last week.
Some revisions were minor editing to start the shift to the new style (active voice instead of passive voice) of the soon to be released 2003 Standard Spec. Book.
The more major changes were:
Added a note stating that moving existing signs to a temporary location on temporary supports will be subsidiary to this item. This note is needed because the latest B&C sheet states that this work should be paid for.
Changed the note pertaining to the electrical and placement requirements for an ignition oven in the field office lab. Not all ovens are the same so the new note directs installation to the manufactures specifications instead of stating exactly what to do.
Added a note pertaining to pavement drop-offs.
Item for Compost Manufactured Topsoil:
Please start using the latest notes for all projects NOW. For projects already in the PS&E review process, Felix's Office will coordinate needed updating with Austin.
October 17, 2002
In case you don't already know it, all on-system illumination designs MUST be in accordance with the TxDOT Traffic Operations Manual and AASHTA. The best way to ensure the design meets the requirements is to use the "Newvolt" and "Serpole" programs that were developed by TxDOT and are based on the Manual's procedure. Use of these programs is not required but please be advised that the Illumination Section of the Traffic Division will use these programs to check illumination designs during the PS&E process and if they come up with a different answer, it could lead to confusion and unnecessary delays to get the differences resolved. So use of these programs is "highly recommended". These programs can be found in the Standards and Forms section of the San Antonio Districts Home Page area on the TxDOT Web-site.
Additional benefits to using these programs are that they will help create the service data chart with all of the required information; relay information will NOT be shown on the illumination layout sheets and they can be used for temporary and permanent illumination systems.
All of the above pertain to on-system illumination systems. If for off-system projects, a local government agency (City or County) has their own design requirements, they can be used as long as their procedure is approved ahead of time. If the local government doesn't have a pre-approved illumination procedure, the design will have to be accomplished based on the same requirements as on-system projects.
I'm nowhere close to knowing the details pertaining to illumination design. All I'm doing is passing on Austin's recommendations but if you have any questions or need additional information, let me know and I'll get answers from Karl Burkett's Office in Austin.
October 17, 2002
The Master list of General Notes has been updated. The following is a brief summary of the changes. The changes affects both the English (E) and Metric (M) sets.
1. The phone numbers for the utility locators in note G-4 were changed to match the numbers shown in the San Antonio Area Utility Coordination Council Listing. The designer needs to add other phone numbers for projects outside Bexar County and for other known utility companies within the project.
2. Got rid of note 9-2 pertaining to TxDOT paying the phone bill for the TxDOT Field Office so the Spl. Prov. that paid for the phone bill through the Force Account Procedure will not be needed anymore. This note has been replaced with a note under Item 504 where the Contractor will be required to provide the phone lines, the phones and pay the phone bill with NO direct payment from TxDOT. The designer has to show how many lines and how many phones will be needed in the field office.
3. Note 423-1: Requires Type A material for backfilling the straps, mesh, etc. of precast retaining walls.
4. Note 502-3-C: All Truck Mounted Attenuators must meet NCHRP 350 crash requirements.
5. Note 540-2: The material to fill-in the concrete blockouts for MBGF posts has to be low strength grout. Use of ACP (hot or cold) to fill in the blockout has been eliminated.
6. Note 611-1 This note pertains to how to handle illumination ballast that might contain PCB and how to handle the lights.
7.Note 3146-1-B: The designer has to show which Pay Adjustment Schedule shown on the referenced Ride Quality Spl. Spec. will be used for the project.
August 2, 2002
The following is a memo from Bridge Division with regards to bridge replacement and rehab funding requirements and contains an attachment from FHWA.
The FHWA is concerned with the number of structurally deficient (SD) and functionally obsolete (FO) bridges and the amount of approach roadway work being funded with the Highway Bridge Replacement and Rehabilitation Program (HBRRP).
The attached letter from the FHWA addresses the limitations on HBRRP funding of approach roadways. Approach roadway work beyond these limitations should be funded with another category of funds. HBRRP projects under development should be re-evaluated to determine if other funding is required for approach roadway beyond these limitations.
Attachment: FHWA Letter
To: Ms. Mary Lou Ralls, P.E.
Dear Ms. Ralls:
Each year, the total number of deficiency bridges is reported to Congress. Although many deficiency bridges are replaced or rehabilitated, the number of deficiency bridges increases yearly. In 1986, a HBRRP funding limitation was established as an attempt to control the utilization of funds to bridge function as much as possible. The target purpose for the HBRRP funds is to replace or rehabilitate deficiency bridges. This HBRRP funding limitation has since been overlooked. It is necessary to address the importance of reducing the number of deficiency bridges for public safety. In order to adequately reduce the number of deficiency bridges, HBRRP funds limitation must be re-emphasized and funds used for roadway work must be limited.
Thus, approach roadway work for HBRRP projects are limited to:
Roadway costs not included in the above limitations should be assigned to funding categories other than Category 6. In special circumstances, roadway costs that have no other category funding available, will be considered for off-system bridge replacement projects.
If you have any questions or would like to discuss this further, Please contact me.
May 1, 2002
The Master list of General Notes has been updated. The following is a brief summary of the changes. The changes affects both the English (E) and Metric (M) sets.
Note G-16 (E) & (M): Added the words "if applicable" because not all projects have an actual environmental document,
Note 160-1 (E) & (M):
New Note 1027-2 (E):
New Note 1009-2 (M): This note revised the existing 160-1 (E) & (M) general notes and adds a new note to the CMT Item. The note adds wording to clarify that the windrow and/or stockpiling as well as the sediment control measures will be considered as subsidiary.
Note 162-2 (E) & (M): Included "Compost Manufactured Topsoil" (CMT) as part of the general note.
Note 450-1 (E) & (M): This note was removed. (Reminder T-6 is allowed for roadways with posted speed of 45 mph or less.)
Note 502-3 C (E) & (M): Added wording to clarify the all TMA's used on TxDOT projects after Jan. 1, 2003 must meet NCHRP 350 requirements.
Note 531-1(E) & (M) changed to 5866-1 (E) and 5433-1 (M): The change in the note reflects the requirements of new Special Specification Item 5866.
Note 540-1 (E) & (M): The note was changed to allow the use of composite material posts and calls for round posts with domed tops.
New Note 618-2 (E) & (M): This note deals with conduit used on City of S.A. Illumination projects. The City requested that we call for a minimum depth of cover of 36 inches (914 mm) instead of 18 inches (457 mm).
New Note 3146-9: This note was added at the request of our District Lab Engineer as a result of some conflicts during HMACP operations.
Note 4438-1 (E) & (M): Made this a required note whenever we call for Flowable Backfill on our projects.
April 17, 2002
The list of due dates for PS&E's that will be processed for letting in FY 2003 is now posted on the San Antonio Districts' Bulletin Board and the TxDOT Web-site. Everybody involved in PS&E submissions should already be familiar with the procedure but I'm going to cover some of the main points for newcomers to the process.
The above process involves a considerable amount of work in just one month especially on large complex projects and on off-system projects that involve an outside agency and their consultant. For this reason, if the due dates are not going to be met, consider moving the letting one month vs. asking us to accept a late submission.
Austin will accept late submissions but they report the late submissions to TxDOT's Main Office and this information is used when the District is evaluated so we need to avoid late submissions.
Please forward this message and the Schedule to your designers.
January 16, 2002
From time to time a driveway permit, sidewalk or drainage permit has been approved in which the consulting engineer has not properly shown the location of existing TxDOT highway light poles, ground boxes, or electrical meter loops (serving overhead sign lighting or highway lighting) that must be relocated and modified for the driveway or drainage construction.
Since most TxDOT owned highway lighting is located in the median of a freeway or next to the main lanes of the freeway, it is unusual to find TxDOT light poles between the highway and the ROW; but this does occasionally occur on roads like Wurzbach Parkway or certain major freeway intersections and other TxDOT highways. Circuit breaker panels and meter loops serving TxDOT electrical facilities are most often located at the ROW line.
Since the consultant engineer typically fails to show this important information on the plans, it becomes the primary responsibility of the Area Engineer and/or Maintenance Supervisor to review the field conditions before the driveway permit or other permit is approved to determine if any TxDOT electrical facilities must be relocated or modified. If TxDOT electrical facilities must be modified, the driveway permit or other permit should not be approved until accurate engineering plans (prepare by a consulting engineer) for the relocation or modification of TxDOT electrical facilities have been submitted to my office for review and approval. My office will coordinate with Roy McCue to insure that these electrical plans are in accordance with TxDOT standards and Roy's electrical crew will perform the inspection of the electrical modifications in the field.
If a driveway permit or other permit has been approved and driveway work or other private entity work has begun and it has become apparent that they have or will encounter TxDOT electrical facilities, the TxDOT inspector should shut down all private work until we have a chance to review and approve the plans for modifications to TxDOT electrical facilities. It is absolutely critical for us to insure that all modifications or relocation of TxDOT electrical facilities are done in accordance with TxDOT requirements. Your attention to this matter is sincerely appreciated.
If the Area Engineer and/or Maintenance Supervisor staff have any questions about possible TxDOT electrical facilities that may conflict with a driveway permit or other permit, please call Roy McCue at 615-5995 for assistance and they will be glad to come look at this site.
January 7, 2002
This message is to remind you that Mr. Kelly wants us to take aesthetics into account in all of our projects. The designer can't go crazy where the cost of a project increases by a considerable amount but there are a few things that should be addressed in all of our projects.
1. Retaining Walls: We should NEVER set up plain/concrete colored retaining walls because most walls are visible from the mainlanes, frontage roads, cross streets, homes/businesses, etc. First, determine the overall theme (shape and color) for the project. "Beauty is in the eye of the beholder", sometimes the theme has to match/blend with other projects and most engineers are not trained in aesthetics so if the designer needs help, Mr. Kelly, Julie, Clay, myself, our staffs and a bunch of other folks at the District are ready and willing to help. We don't know anymore about aesthetics than your in-house or consultant designer but several heads are better than one.
2. Concrete Sideslopes: Like retaining walls, riprap sideslopes are visible to the public so the best thing to do is to eliminate the need for them by designing flatter grass slopes. If there isn't enough space to flatten the slope, consider a short wall and if this is not possible, consider stamped/colored concrete. Pavers are an alternative to concrete but keep in mind that grass will grow between the pavers so the area needs to be fairly flat and easy to get to for maint.
3. Riprap Ditches: Try to design the drainage structures and ditches where they're not too steep or too flat to eliminate the need for concrete. If a concrete ditch can't be avoided, consider stamped/colored concrete for the side slopes and plain but colored concrete for the ditch bottom.
4. Bridges: A bridge with several bents and several columns per bent will not look good even if we do something fancy to the bents/columns. So, try for a bridge with beams that can handle longer spans and bents with fewer columns. The public doesn't see bents at rivers and creeks but from an environmental and maint. standpoint, the fewer bents and columns per bent we've got in or near the water the better.
A plus to all of the above is that a concrete surface that isn't plain will hopefully decrease the amount of graffiti and grass filters runoff while concrete doesn't.
I only addressed a few things that pertain to our projects so if there are some other situations that normally come up on our projects and you have an idea for an aesthetic treatment, please share it with the rest of us.
January 7, 2002
We're getting ready to update the subject notes. So you won't have to look through all of the notes to find what's different, here's a summary of the main changes.
Note 5-1: Added a note for referencing the pavement markings BETTER at OSB signs, TMS arrows, etc. locations to make sure the lane markings placed after the sealcoat and/or overlay end up under the signs, arrows, etc.
Note 9-2: Reworded the note about the State providing the phones and the contractor providing the phone lines to the field office.
Note 504-2: Got rid of the note because it's already addressed in note 9-2. This moved the remaining notes for Item 504 up one number.
All notes for Item 540: Revised the notes due to the 2001 MBGF State Standard update.
Note 5519: Got rid of the sentence pertaining to payment because it's covered in the Spl. Spec.
November 26, 2001
The Traffic division in Austin updated the subject Standard sheets last year so all of our plans should be using the 2000 sheets instead of the 1998 sheets. When the 98 sheets were updated to 00, Austin did NOT provide the Metric version but we still have several projects in the design stage that will be let in Metric so Rob Haley ( W/ Felix's Plan Review Office) converted the sheets and we're now ready to place them on our Web page as San Antonio District Standards for all designers to use.
There are a few things I need to point out pertaining to the ED Sheets:
Note B. 4. on the ED 3 sheet requires the contractor to do some grounding related work when an existing ground box is utilized as part of the project. This additional work will not be paid for directly but the plans must show the boxes and describe the work that will be required. If the plans don't show this, the work still has to be done but since it wasn't shown, it'll becomes extra work and you'll have to pay for it.
Note B. 5. on the ED 3 sheet states that the Engineer may direct the contractor to do the same grounding work to existing ground boxes that were not utilized as part of the project. It says "The Engineer may direct" but we need this work done on all of our projects that have other electrical related bid items to ensure that all ground boxes are properly grounded when the project is completed. Since the grounding work will be the only thing done to the boxes, the Engineer has to identify the boxes in writing and this work will be paid for separately. To avoid having to do this during the construction stage, your designers need to address this in the plans and provide a bid item & quantity for this work.
ED 5 provides Service Enclosure details. On previous projects where CPS was going to assume maint. and operation of an illumination system, we were using a CPS enclosure detail instead of TxDOT's standard so we had to use a District Standard Sheet. Recently CPS told us they'll accept the State Standard so we're going to get rid of the District Standard for the Type S service enclosure. We're still going to have a District Standard for the ED 5 but it's just the Metric version of Austin's English sheet.
Austin did convert ED 11 to Metric so we didn't have to do so it'll remain a State Standard instead of a District Standard but to make it easier for the designer to call it up, we are going to place this State sheet with our District sheets.
October 18, 2001
The following is a memo from the Bridge Division Director with regards to the new Hydraulic Design Manual:
Please refer to the Manual Notice 2001-1 attached below, which gives the Administration's approval of a new Bridge Division online manual. The Hydraulic Design Manual provides guidance and recommended procedures for analyzing and designing effective highway drainage facilities. It will be useful to TxDOT personnel and consultants involved in the design of drainage systems. The units for this manual are metric; the manual will be updated to dual units next year. This new manual replaces the Hydraulic Manual (third edition, 1985).
This manual is now available on both the Internet and TxDOT's Intranet:
This manual is part of the Bridge Collection of TxDOT Manuals. Any questions about this manual should be addressed to David C. Stolpa, P.E., Manager of the Hydraulics Branch in the Bridge Division. You may reach David by phone at 512-416-2271.
From: Kirby W. Pickett, P.E., Deputy Executive Director To: Districts, Divisions and Offices
RE: Hydraulic Design Manual Effective Date: October 1, 2001
This manual will provide guidance and recommended procedures for the design of Texas Department of Transportation drainage facilities.
This manual replaces the Bridge Division Hydraulic Manual, Third Edition.
The manual contains fourteen chapters Manual Introduction; Policy and Guidelines; Types of Documentation; Data Collection, Evaluation, and Documentation; Hydrology; Hydraulic Principles; Channels; Culverts; Bridges; Storm Drains; Pump Stations; Reservoirs; Storm Water Management; and Conduit Strength and Durability.
For more information regarding any chapter or section in this manual, please contact the Hydraulics Branch of the Bridge Division.
October 8, 2001
The following memo is from Bridge Division with regards to updating the Concrete Slab and Girder Standards:
New sets of Concrete Slab and Girder Standards (English and Metric) with an issue date of October 2001 are posted at the TxDOT web site and available for immediate use. The following roadway widths are available: 24 ft (7.2 m), 28 ft (8.4 m), 30 ft (9.0 m), 38 ft (11.4 m), and 44 ft (13.2 m).
The metric standards were revised to conform to the significant changes that were made to the pan forms when the new English set was issued in April 2001. The most significant change is the redesigned overhang with an 8-inch (204-mm) thickness. In some cases, the number of pans needed for a particular roadway width changed. These changes will make the use of pan form girders less confusing on the remaining metric projects. In addition, a new English set is being issued to correct several small errors.
The new standards are available from the Bridge Standards (English and Metric) web pages in MicroStation® "dgn" and Adobe® Acrobat® "pdf" formats; therefore, copies of the sheets were not included with this memorandum. Effective immediately, these new standards replace the old metric sheets that were last issued on April 1997 and the English sheets that were issued April 2001. Some of these standards have had significant changes since their initial release; therefore, the user is strongly encouraged to check the TxDOT web site for the most current version. Please distribute this information to the appropriate district staff and area offices as well as those consulting engineers working on TxDOT projects.
September 10, 2001
The following is a memo from the San Antonio District Bridge Engineer with regards to the use of Bridge Protective Assembly (BPA) on future projects.
In the past a Bridge Protective Assembly (BPA) was required if clearance was inadequate. The bridge division no longer requires that a BPA be placed on concrete beams. The protection they provide only is for minor impacts, which are not a major maintenance problem. For major impacts to concrete beams, the BPA provides little protection and may cause a safety hazard by falling into the traffic lane after impact. Repair is difficult after impact since the new angle must align with the existing bolt locations, in most cases they are just not re-installed.
Currently when mounting a sign on a bridge, the BPA sheet is the only standard available to do so. Sign mounting details will be separated into its own standard in the near future. The bridge division is going to eliminate the BPA standard eventually.
It is therefore recommended not to use BPA's in future projects.
Jon H. Kilgore, PE
September 5, 2001
The attached memo was send out nearly 3 years ago. The memo urges use of the Book by both field and design personnel but as far as I know, our most of our designers ( in house & consultants) have not been using it.
At a CEC/TxDOT joint meeting on 09 05 01, I gave the consultants a copy of the memo and instructed them to get a copy of the Book from Austin and start using it in their design. The Book is available by calling Jeannie Black at 512 416 3134. It's free for TxDOT designers but consultants will have to pay $8.39 for the Book, $5.00 for the Binder and $1.00 if they use a credit card.
Please make sure all of the designers your Office is managing use the Book!
To: All District Engineers
In the past, field crews had to rely upon the Texas Manual on Uniform Traffic Control Devices (Texas MUTCD) and the TxDOT Traffic Control Standard Sheets, to determine the most effective placement of guide signs, delineation, and object markers for conventional roadways. However, these documents only address a few typical situations. As a result, many signing and delineation situations are treated inconsistently throughout the state.
Due to the efforts of TxDOT and Texas Transportation Institute personnel, the Sign Crew Field Book, 2nd Edition- A Guide to Proper Location and Installation of Signs and Other Devices is ready for distribution.
The Sign Crew Field Book is intended to provide field and design personnel with information beyond that contained in the Texas MUTCD or the TxDOT Traffic Control Standard Sheets so that signing and roadside markers for conventional roadways can be applied in a more uniform manner. This field book does not supersede, but rather provides additional guidance with respect to standards, recommended practices, or other requirements established by other TxDOT documents.
The 2nd Edition contains a new chapter dedicated to roadside markers. Roadside markers consist of object markers, delineators, and barrier reflectors. They are intended to provide motorist recognition and guidance information about roadside features. This chapter includes treatment guidelines for horizontal curves, bridges, guardrail, and exit/entrance ramps to controlled access facilities. Additional information is also provided so that proper roadside marker treatments can be implemented in practically any situation.
It is urged that your field and design personnel use the guidance provided by the Sign Crew Field Book as they work to upgrade and install new sign and roadway marker installations. If you have any questions concerning information or use of the field book, please call Tom Newbern at (512) 416-3200 or Greg Brinkmeyer at (512) 416-3120.
Attached is a memo from the Bridge Division pertaining to retaining walls. It addresses design, construction and maintenance so please forward this material to your folks involved with walls in any of these areas.
When you read the memo, you're going to see that there are a lot of decisions that need to be made during the design of a wall. They include such things as selecting the right type of wall that best fits the existing and proposed conditions, additional testing of the existing soils, type of backfill (A, B, cement stabilized, 1 vs. 2 ft. of wall embedment below finished grade, etc). We'd like our plans to be as standardized as possible. We'd like to make things easier for the designers but every project is a little different so it's not possible for Austin or the District to make these decisions ahead of time. Please remind your designers to take all of the existing/ proposed conditions and the things covered in the memo into account.
If your project has some unique conditions or you just want to verify something, contact Jon Kilgore's Office and he'll work with you and coordinate with the Austin experts if/when needed.
MEMO FROM BRIDGE DIVISION
Based on our analysis of recent failures, we would like to provide the following recommendations regarding the design, construction and maintenance of retaining walls, with particular emphasis on proprietary Mechanically Stabilized Earth (MSE) walls. There are two primary issues: 1) selection of the proper system for a given location and 2) proper construction practices. Further, proper maintenance and design are also important for long term wall performance. Below are our recommendations to address each of these issues.
We have noted MSE walls specified in inappropriate locations. In many situations, especially cuts, MSE may not be the most appropriate wall type. Often the additional excavation and shoring required for installation of MSE walls in cut situations make them uneconomical and difficult to construct.
Sometimes MSE walls are selected because only a geometric layout and a standard sheet are required in the plans (the final detailed drawings are produced as shop drawings). This minimal design effort up front makes MSE walls a popular choice among engineers with limited time and resources. Although tied-back, soil nailed, drilled shaft and spread footing walls all require considerably more design effort and time, they are preferable in some cut situations.
The Texas Cone Penetrometer is poorly correlated for very low soil strengths and may yield overly conservative results. When evaluating stability of walls on soils weaker than 20 blows per foot, it may be appropriate to conduct laboratory or in-situ testing in addition to the TCP. Triaxial or direct shear laboratory tests will generally yield more accurate soil strengths for this type of analysis.
Engineers in the Geotechnical Branch of the Bridge Division are available to assist with the determination of testing for specific situations and with the slope stability analysis.
Actual soil conditions -
Adherence to plans and specifications -
Base backfill -
Filter Fabric -
Periodically inspect walls for evidence of backfill loss, loss of joint seals, or movement. Reseal joints, particularly those that may allow surface water to enter the wall backfill. If evidence of backfill loss is observed, backfill the effected area with select fill if the area is accessible, or use flowable fill if access is restricted. Water infiltration into voids in walls can cause excessive pressures within the wall and result in displaced panels and wall failures. Treat voided areas when they are small and manageable, as they will always increase in size with time.
MSE Walls have been the most common retaining wall type on TxDOT projects for the past two decades. The advantages of MSE walls include their low cost, low design effort, speed of construction, and attractive appearance. MSE walls will continue to be used in large quantities on TxDOT projects in the coming years. With this in mind, we recommend that the following be considered on upcoming projects utilizing MSE walls:
Retaining walls serve us well, but there are some key points for successful wall performance: the correct system must be chosen for each location and proper construction practices must be employed. Also, as described above, there are a number of design and maintenance issues that are equally important.
Please let us know if we can be of any help with your retaining wall issues. Feel free to call Mark McClelland, P.E., at (512) 416-2226, Ronnie Medlock, P.E., at (512) 416-2518, or me at (512) 416-2183 as needed.
As you know, the subject Standards can now be downloaded from the District's Web site and the Bull. Board. From time to time, we have to update existing sheets and provide new sheets to keep up with the changing times. We just got through with an update so I need to tell you what we did and why.
1. Austin updated the Electrical Detail (ED) Standard Sheets late last year and our District Standard for the Service Enclosure is a modification (to get it the way CPS wants it) of the State's sheet so we had to update ours. It was ED(4)-98 and it's now ED (5)-00. The District's sheet has to be used for illumination systems that are going to be operated and maintained by CPS. For illumination systems outside CPS's service area, the designer has to find out which detail ( State or District) the electrical company wants.
2. Curb Inlets: The Type I through VIII Curb Inlets (constructed outside the pavement edge) provided the details to bolt inlets side-by-side. This resulted in having inlet locations that were very long (up to 40 ft.) and big (full size inlets). To remedy this, the 1 through VIII has been replaced by a "Type I & II w/ Inlet Extensions". For a single inlet, the details are still the same but if you need more than one, you'll bolt an extension instead of a full size inlet. The inlets and the extensions are each 10 ft. long so please use a max. of 1 inlet and 1 extension per location to avoid the 30 to 40 ft. installations that not only look ugly but create problems with existing and future driveways.
3. Curb Inlets: The Type C Inlet is constructed under the roadway pavement to avoid other lines running along the outside of the roadway. The Ty. C did not have a bolting detail so we've replaced it with the "Type C w/ Extension" . As with the Ty I & II, please use a max of 1 inlet and 1 extension to avoid long inlet installations.
4 Single Slope Traffic Rail ( SSTR): There are two State Standard sheets for this rail but they don't provide details for supporting an illumination pole as requested by CPS (to make it easier to get to the pole's handhole). We've had a District detail for several years that is a modification of 1 of the State's 2 sheets but we called both sheets District sheets. Now, whenever there's a project with this rail, the designer will call for the 2 State Standards and if the rail is going to have light poles on top of it, the designer has to call for the District's "Single Slope Traffic Railing With Illumination" for a total of 3 sheets.
There are 12 Electrical Detail ( ED) State Standard Sheets and Austin issued only English sheets so our District Standard for the Service Enclosure is also only in English. If your Office is going to need these details in Metric units, let me know and we'll convert our sheet and whichever of the 12 State sheets you're going to need for the project.
The inlet and the rail standards are available in both English and Metric.
All District Standards were developed to make it easier on designers and contractors. If there's an existing sheet you'd like for us to change or something new you'd like us to address as a standard, let me know and we'll check-it-out. Please forward this information to your in-house designers and consultants.
May 24, 2001
The subject Notes have been revised. Some of the revisions were only minor editing that don't need to be mentioned but there are some changes that I need to point out.
1. Whenever a Standard sheet is modified, we've been showing it as (Mod) on the project's title sheet. Now, in addition to this, we've got to identify the modified sheets (by the name of the Standard) in the General Notes so we've added a note for this.
2. The "Soil Stabilization Practices" note provides a list of Structural Practices for the designer to check off the ones that apply to the project. Marvin Hatter has recommenced a different type of berm but it's not shown on the list and most designers don't even know about it so it's now on the list. It's "Mulch/Compost Filter Berm ( Spl. spec. No. 1023)" and as I said, Marvin Hatter is recommending we use it.
3. Item 100: We've already got a note pertaining to trees and areas of vegetation that the Contractor is required to NOT remove or clear. This note has been expanded to say " To ensure that these areas are not disturbed, the Contractor will be required to place protection fencing when shown in the plans or when directed by the Engineer."
4. Item 162: We've added the following note. " Use organic or non-asphaltic biodegradable material approved by the Engineer as the tacking agent for straw and/or hay mulch applications. Use of an asphaltic material as the tacking agent must be approved by the Engineer"
5. Item 316: A note showed the different type (AC, MC, CRS P, etc.) of materials that will be allowed but this info. is also in the item's description code so there's no need to say the same thing twice in different places. So, other than saying that the rates are based on asphalt, we got rid of the note.
6. Item 432 and 540: We've been requiring a block out at guard fence posts that are within concrete sections. the size of the block out has been changed from 12 inches to 15 to 18 inches to ensure the concrete near the posts does not change how the post is suppose to function when it's hit.
Please pass this on to your designers!
May 7, 2001
New Concrete Slab and Girder (Pan Form) Standards (English) and, new Retaining Wall Standards (English and Metric), were issued April 2001. These standards are posted on TxDOT's web site. You can reach the standards at the following location: http://www.dot.state.tx.us/business/standardplanfiles.htm .
Once at the site, click on "Bridge Standards (English)" under the "Bridge Division" heading. Scroll down to the "Concrete Slab and Girder (Pan Form)" heading or, the "Retaining Walls" heading, or click on "Bridge Standards (Metric)" under the "Bridge Division" heading and scroll down to the "Retaining Walls" heading. Click on the appropriate PDF icon to access the desired standard. By clicking on the PDF icon, the standard can be viewed and printed without the need for MicroStation. Note that by downloading these files, the receiver accepts the terms and conditions of TxDOT's CAD Standard Plan Files Disclaimer.
The Bridge Standards page has also been updated to include copies of memorandums of issued or revised standards dated after September 2000.
April 26, 2001
The list of due dates for PS&E's that will be processed for letting in FY 2002 is now posted on the San Antonio Districts Bulletin Board and the TxDOT Web-site.
Please keep in mind that before the design project manager ( CCMO or Area Office) turns in a PS&E to the District, they're suppose to review it one last time so the due date for the designer (in-house or consultant) will probably be earlier than the District's due dates.
The list provides dates for the different funding and review types of projects and it doesn't depend on the proposed construction yet we've got some very big and complex projects coming up in FY 2002 such as 410/281 & 410/10 Interchanges and other freeway upgrading projects. We'd appreciate it if big/complex projects are turned in earlier than the dates shown.
Austin will accept PS&E's even if we miss their due date a week or two but the District gets a black mark whenever this takes place and this info. is reported to our Austin Main Office. Last year, our District had the highest percentage of late PS&E than the other 4 Urban Districts and Mr. Kelly has instructed us to do whatever it takes to get us off the bottom of the list!
Most PS&E's are turned in to the District in time but a lot of times there's required paperwork missing which means the package was not ready but was submitted anyway just to meet the due date. Another problem is that there's too much time being taken by the designer to address the review comments and we end up being late with our submission to Austin even when the submission to us was on time. It's understandable for a designer to want to take some time off after completing a design project but they need to be reminded that they're not through until the review process is completed.
March 15, 2001
As you know, there are several engineering documents that are required to be signed, sealed and dated by the Engineer and in most cases TxDOT as the Office Of Record, needs the ORIGINAL and not a copy.
As every bodies copy and reproduction machines get better and better, it's difficult to tell if what is submitted is an original or a copy. For this reason, we are going to require the use of a blue ink pen to sign original documents such as reports, plan sheets (for both paper & tracing material) , certification statements, etc.
Please forward this message to all of the engineers on your staff that will be signing engineering documents so they'll know to use a blue pen and we won't have to be asking for this over and over when documents are submitted.