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14 Staff Report - Roberts Road Bridge Closing~pW N 0 COUNCIL AGENDA REPORT OS"G'ASO DATE: APRIL 26, 2005 MEETING DATE: 5/2/05 ITEM NO. 14 TO: MAYOR AND TOWN COUNCIL FROM: DEBRA J. FIGONE, TOWN MANAGER SUBJECT: REVIEW UPDATED REPORT ON THE ROBERTS ROAD BRIDGE CLOSING AND PROVIDE DIRECTION ON THE AVAILABLE OPTIONS A. ADOPT RESOLUTION CLOSING ROBERTS ROAD BRIDGE TO VEHICULAR TRAFFIC, OR B. REPAIR AND REHABILITATE TH EXISTING STRUCTURE, OR C. REPLACE THE EXISTING STRUCTURE RECOMMENDATION: Review updated report on the Roberts Road bridge closing and provide direction on the available options: 1. Adopt resolution closing Roberts Road Bridge to vehicular traffic, or 2. Repair and rehabilitate the existing structure, or 3. Replace the existing structure BACKGROUND: The bridge on Roberts Road across Los Gatos Creek was built in 1918. The design of this bridge was in accordance with the engineering standards and requirements of the early 1900's and is far from today's modern and complex criteria in terms of both structure and seismic design. This bridge was basically a one lane structure used to carry agricultural products across the creek at that time. This bridge has aged and deteriorated over the years and requires attention if Roberts Road is to continue as a route between University Avenue and Blossom Hill Road. The Town Council at its September 20, 2004 meeting reviewed a staff report regarding the condition of the Roberts Road bridge and the options available, which included closure to vehicular traffic, repair, or replacement of the structure. Zz PREPARED BY: OHN E. CURTIS Airector of Parks and Public Works Reviewed by: ? -&Assistant Town Manager _~i, Town Attorney Clerk Administrator Finance Community Development Revised: 4/27/05 2:30 pm Reformatted: 5/30/02 N:\B&E\COUNCIL REPORTS\roberts.rd.bridge.update.5205.wpd PAGE 2 MAYOR AND TOWN COUNCIL SUBJECT: REVIEW UPDATED REPORT ON THE ROBERTS ROAD BRIDGE CLOSING AND PROVIDE DIRECTION ON THE NEXT STEPS APRIL 26, 2005 Council direction was to close the bridge to vehicular traffic. After analyzing before and after traffic counts and conducting an independent structural condition assessment of the bridge, staff was to report back to the Town Council in early 2005. The decision to close the bridge to vehicular traffic was based on a report from Caltrans. Caltrans inspects bridges for many agencies, including Los Gatos. The Roberts Road bridge had the lowest sufficiency rating (31% versus 76-95% for other structures) amongst all of bridges in Los Gatos. Caltrans recommended that prompt action be taken by the Town to address various deficiencies of the Roberts Road bridge. These deficiencies include spalls or holes in the concrete, on the deck, cracks on the structure, and scouring or an eroding away of the concrete by the action of water of the bridge pier and fouundation. Generally, these degraded areas are not visible from the roadway. Iu considering the available options of keeping the bridge open or closing it, the Council considered the input of the local residents and those who remarked on its historical significance and beauty. DISCUSSION: Staff held a meeting with the residents of the Roberts Road area on November 16, 2004 to go over various issues related to the bridge and its closure in advance of the actual closing of the bridge. The purpose of the meeting was to seek input on how best to implement the closure. This meeting was attended by nearly 3 0 residents. Attendees not only sought information about bridge closure, but also inquired about repair and/or replacement of the bridge. Generally, the residents who attended the meeting expressed concern about the closure. They raised questions about the replacement of this bridge with a new structure which could meet current standards and would have an architectural element similar to the current bridge. They supported having a new bridge striped as a one-lane bridge after its construction, similar to the current configuration. Some of the residents were concerned with the impacts of cut-through traffic on Oak Meadow Drive and were informed that traffic counts would be taken both before and after the closure to determine if there is any cut- through traffic or if this is only a perceived problem. On November 23, 2004 staff notified the residents of the area and the meeting attendees of the outcomes of the meeting and informed them of the next steps and Council discussion on this matter. (See attachment). One result of this meeting was that bridge closure was delayed until after the holidays. The bridge was closed on January 10, 2005. Traffic counts were taken at a number of locations in the vicinity of the bridge, for a week both before and after closure. The following is a sumunary of average daily traffic counts before and after the bridge closure. This analysis indicates that there has not been cut-through traffic on Oak Meadow Drive as a result of the bridge closure and that former users of the bridge have turned to using University Avenue and Blossom Hill Road as the preferred circulation route. PAGE 3 MAYOR AND TOWN COUNCIL SUBJECT: REVIEW UPDATED REPORT ON THE ROBERTS ROAD BRIDGE CLOSING AND PROVIDE DIRECTION ON THE NEXT STEPS APRIL 26, 2005 Location Before Closure Weekday Nov-04 After Closure Weekday Feb-05 Roberts Road from Ohlone to Blossom Hill Road 971 459 Roberts Road from Oak Meadow Drive to Ohlone 817 0 Roberts Road from Brickway to Oak Meadow Drive 916 151 Total on Roberts Road 2704 610 Oak Meadow Drive north of Roberts Road West 181 134 Oak Meadow Drive south to Blossom Hill Road 188 226 Total on Oak Meadow Drive 369 360 In addition to the above traffic counts and evaluation, an independent structural inspection and evaluation of the bridge was also performed (Attachment 2). This report confirmed the Caltrans report as to the condition of the bridge and the need to take actions to rehabilitate or replace the bridge if it was ever to be reopened to vehicular traffic. The report also pointed out the need to place a weight restriction on the bridge if it was ever to be reopened prior to being repaired. By limiting the allowable vehicle weight on the bridge, the service life may be prolonged. This would enable a deck structure, which is in poor condition, to survive without failure for an extended time. For about six months prior to the closing of the bridge, staff posted signs on the bridge approaches limiting the weight to 10 tons. However, it was not practical to enforce this requirement and there were many anecdotal reports of heavier vehicles using the structure, likely because it was a convenience to do so. Even though the local companies with heavy vehicles had been informed of this new condition, they did not appear to widely adhere to this requirement. Signage and contact with the relevant local firms with heavy vehicles did not serve to prevent heavy vehicles from using the bridge when it was open to traffic with weight restrictions. It is not possible to estimate the remaining life of this bridge, as many factors such as weather and creek flows in the channel could have a maj or impact to the bridge foundation which has experienced substantial erosion and scouring and could become a major source of failure. Further, the bridge is used for transmitting a number of utility lines (sewer, water, gas) across the creek and any failure of the structure would have detrimental impacts to the community and to the Los Gatos Creels. PAGE 4 MAYOR AND TOWN COUNCIL SUBJECT: REVIEW UPDATED REPORT ON THE ROBERTS ROAD BRIDGE CLOSING AND PROVIDE DIRECTION ON THE NEXT STEPS APRIL 26, 2005 Very little resident response has been received by staff beyond the first week of full closure in January. During that first week, in which many drivers apparently did not believe the "bridge closed" signs, there were may calls to the Town about u-turns and errant drivers. When these activities abated, the calls stopped. One email was received which praised the Town for closing the bridge citing the reduction of traffic on Roberts Road. After the completion of the above evaluations, the following options are presented to the Council for consideration: Option 1- Close the Bridge Permanently to Vehicular Traffic, Keep it Open for Pedestrians and Bicyclists Under this option, the bridge would remain closed as it is presently. Traffic counts collected in November 2004 and February 2005 indicate that "cut-through" traffic did not develop on Oalc Meadow Drive, which was one of the primary concerns regarding the closure of the bridge. By causing through traffic to use University Avenue and Blossom Hill Road, which always was the intended route for through traffic in this area, no adverse impacts have been created on those streets. The increased flow is well within the capacity of those two streets and their intersection to accommodate it. By enabling a continued usage by pedestrians and bicyclists without allowing vehicles, the roadway is safer for the users than when the roadway was shared with motorized traffic, and this is a benefit to continued closure. Attachment 3 is an e-mail from a Roberts Rd. resident thanking the Town Council for closing the bridge to vehicular traffic for this and other reasons. A further concern that was related to the bridge closure was the possibility that young people might use the bridge as a gathering place. This, at least so far, has not happened. The possibility of this area becoming a problem spot in the future is no more acute than that possibility in any other area of the Town. Closing of the bridge to vehicle traffic has led to changes in the circulation patterns of the adjacent neighborhoods. Council may have considerations in addition to the staff observations in evaluating the continued closure of the Roberts Road Bridge. If the bridge is closed to all but pedestrian and bicycle traffic, there are a few long range conditions that should be understood. The first of these is that the existing railings should be made safe. They have been damaged over the years and those damaged areas require repair. Additionally, the existing railing needs to be raised to meet current safety standards for bridges. Staff has not developed a reliable estimate of the cost at this time. If this is the option selected by Council, staff would prepare a preliminary design and cost to be included in the Capital Improvement Program for FY 2005-06 as a funding priority. PAGE 5 MAYOR AND TOWN COUNCIL SUBJECT: REVIEW UPDATED REPORT ON THE ROBERTS ROAD BRIDGE CLOSING AND PROVIDE DIRECTION ON THE NEXT STEPS APRIL 26, 2005 Secondly, the bridge will continue to deteriorate, even if there is no vehicular traffic using it. The middle pier and the abutments, which are the foundations ofthe structure, show signs of severe wear and this is contributory to the weakness of the structure as described by Caltrans and the independent structural engineers report. At some stage, not necessarily immediately, repairs to these bridge elements would be required, even if the bridge is to remain closed. The cost of these repairs, though unknown at this time, are expected to be the significant portion of any repair project that would enable the bridge to be opened to vehicular traffic again. Again, a preliminary design and estimate of these costs will need to be developed if Council selects this option, but the prioritizing of this repair can be delayed to another year in the Capital Improvement Program budget and work plan. Given the current condition of State finances, and the unknown policy of Caltrans regarding bridge repair, staff believes the state would not fund a bridge repair in which the product of the repair was abridge that remained closed to traffic. There maybe other funding sources for such a project, but staff has been unable to locate asource for funding that type of project. Based on staff's review of data and other observations, traffic can use the intended routes of travel without unintended consequences. However, it is recommended that under continued closure, the Town make the repairs and safety upgrades to the bridge railings a funding priority. The Town should also plan for eventually snaking significant repairs to the bridge substructure as part of a longer range plan to continue the use of the structure for pedestrians and bicyclists. If the Council selects this option, the attached resolution must be adopted pursuant to Vehicle Code Section 21109. Option 2 - Repair and Rehabilitate the Bridge Structure If the bridge is to be reopened to vehicular traffic, it will need extensive rehabilitation of the deck, rails, foundation, and support structure below the deck at an estimated cost of $1,000,000. This rehabilitation would repair the structural deficiencies of the bridge and make it earthquake safe. It would not raise it to current design standards, which are related primarily to the width of the structure. Raising a structure to current design standards is a requirement of Caltrans in order to fund a bridge rehabilitation project. This estimated rehabilitation cost would have to be funded by the Town. It would take a minimum of 18 months to design, process and review, and perform the repairs to this bridge. This is a viable project, provided that funding canbe found or made available for it. From a fiscal perspective, staff does not recommend this approach if the Council determines the bridge should be reopened. If this option is selected, staff recommends that the bridge remain closed to vehicular traffic until it is rehabilitated. PAGE 6 MAYOR AND TOWN COUNCIL SUBJECT: REVIEW UPDATED REPORT ON THE ROBERTS ROAD BRIDGE CLOSING AND PROVIDE DIRECTION ON THE NEXT STEPS APRIL 26, 2005 Option 3 - Replace the Bridge An option for keeping this road open to all users is to replace this bridge with an adequate structure. A new bridge can be designed with architectural features similar to the existing bridge, in addition to having a proper width. Grant funding could be used for the replacement project and architectural features on the bridge, as long as such features are similar to the existing bridge. Other reasons for replacing the bridge include improved sight distance and traffic safety, pedestrian and bicycle safe railings, lower maintenance and repair costs, and a much higher level of seismic protection. The new bridge would be a single span structure and would not have columns in the middle of the creels like the existing structure. This will eliminate all problems with the erosion of foundation in the middle of the creek that we face with the existing structure. A replacement bridge has an estimated cost in current dollars of $1,500,000. Eighty-eight percent of the cost can be funded by Caltrans grants for bridge replacement. It would take approximately three years from the time Council direction is given to replace the bridge to the time when actual construction of the new bridge would take place. There would be time needed to apply for and secure funding from Caltrans, design the project, and go through various regulatory agency reviews. In addition, a new structure can be designed and built incorporating aesthetically pleasing architectural elements. One of the other benefits of replacing this bridge is to provide proper support for the utility lines which are currently suspended from the bridge deck. These utility lines are suspended from the bridge by brackets and straps. A new bridge would place these utility lines inside the structure and provide a much higher level of protection and security especially-in cases of seismic activity. Along with the benefits of replacing the existing structure, there are some negatives to consider. Financially, about 12%, or $180,000 of Town funding would be needed to enable the State funding of a new structure to take place. The replacement would cause a disruption in trail use during construction. A new structure would look different architecturally than the present structure. And lastly, the need for a vehicular bridge at Roberts Road should be determined. These considerations should be evaluated before any decision on any replacement is made. If the bridge is to be reopened, staff would recommend that the replacement alternative be selected. This is based not only on the favorable financial comparison of the repair versus replace alternatives, but also on the consideration of the time to complete the project and the structural superiority of a new structure over a repaired structure. If this option is selected, staff recommends that the bridge remain closed to vehicular traffic until replaced. PAGE 7 MAYOR AND TOWN COUNCIL SUBJECT: REVIEW UPDATED REPORT ON THE ROBERTS ROAD BRIDGE CLOSING AND PROVIDE DIRECTION ON THE NEXT STEPS APRIL 26, 2005 CONCLUSION: This report provides information regarding impacts of closing the bridge to vehicular traffic since mid-January. Viable approaches to the future for the bridge have been examined. Staff seeks Council direction on continuing the closure of the Roberts Road Bridge or on seeking channels for funding repair or replacement. ENVIRONMENTAL ASSESSMENT: . This project is not defined under CEQA. A Notice of Exemption is not required. FISCAL IMPACT: Depending on the direction given by Council, staff will update the Capital Improvement Plan accordingly. If the structure is to be closed permanently, that will require one set of safety projects in the next fiscal year and further capital expenditures in the long term. If the direction is to repair the existing structure and reopen it to vehicles, another Capital Improvement Program update of an estimated $1 million will be needed, most likely for another year in a five year budget plan. Currently, the FY 2004/09 Capital Improvement Plan allocates $100,000 of local GFAR funding and $900,000 of state grant funding totaling $1,000,000 for this project. If the direction of Council is to seek replacement funding, the cost estimate used to develop these figures will need-to be updated. We will also update the CIP for the future years as this project moves along. If the bridge is to remain closed to vehicular traffic, staff should proceed to develop a preliminary design and estimate of cost of the repair that would be needed as soon as possible. If the structure is to someday be reopened to vehicular traffic, using either scenario of repair or replacement, staff would recommend that the bridge remain closed as it is now. Under either of these options, staff would install more attractive fixed barricades at the bridge ends to replace the temporary barricades currently in place. Attachment: 1. Resolution closing Roberts Road Bridge to vehicular traffic 2. Roberts Road Bridge Evaluation Report 3. E-Mail from Julene Dee Pief Distribution: Anne Lamborn, 7 Monroe Court, Los Gatos, CA 95030 Peggy Willey, 134 Ohlone Court, Los Gatos, 95032 Oak Meadow Drive Homeowners Association RESOLUTION RESOLUTION OF THE TOWN COUNCIL OF THE TOWN OF LOS GATOS CLOSING ROBERTS ROAD BRIDGE TO VEHICULAR TRAFFIC WHEREAS, the Town Council of the Town of Los Gatos desires to provide roads, streets, and bridges that are safe for public travel; and WHEREAS, the bridge at Roberts Road has been found to be unsafe for continued travel in the rnanrrer it was originally intended; and WHEREAS, the rnostprudent option currently available is to close the Roberts RoadBridge to vehicular traffic; and WHEREAS, the Vehicle Code Section 21109 allows local authorities to adopt rules and regulations by ordinance or resolution regulating traffic on bridges. NOW, THEREFORE, BE IT RESOLVED THAT, the Town Council of the Town of Los Gatos hereby orders the closure of the Roberts Road Bridge to vehicular traffic, and further directs staff to place permanent barriers preventing its use by vehicular traffic and enabling bicyclists and pedestrians continued safe passage on the closed bridge. PASSED AND ADOPTED at a regular meeting of the Town Council of the Town of Los Gatos held on the day of , 2005 by the following vote: COUNCIL MEMBERS: AYES : NAYS : ABSENT: ABSTAIN: SIGNED: MAYOR OF THE TOWN OF LOS GATOS LOS GATOS, CALIFORNIA ATTEST: CLERK ADMINISTRATOR OF THE TOWN OF LOS GATOS LOS GATOS, CALIFORNIA ATTACHMENT 1 BRIDGE EVALUATION REPORT FOR ROBERTS ROAD BRIDGE OVER LOS GAI'OS CREEK LOS GATOS, CALIFORNIA March 2, 2005 2004385 Attachment 2 E3 ASSOCEATE BFic STRUCTURAL ENGINEERS '1871 The Alameda, Suite 200 San Jose, CA 95125-1752 Telephone 408-298-5515 Facsimile 408-22B-8114 Town of Los Gatos Public Works Department 41 Miles Avenge Los Gatos, CA 95031 Attention: Kevin Rohau Subject: Roberts Road Bridge Evaluation Dear Kevin: March 2, 2005 This structural evaluation of the existing Roberts Road Bridge presents the findings of our investigation. We hope this report will be sufficient for the Town to compare alternatives for the crossing. The findings of this report are limited to those elements of the structure that are visible and assumes the bridge constriction conforms to the original construction plans. Should you have any questions, please do not hesitate to call. Sincerely, RTES, INC. PB CARDOSA . Devlin Principal cr-_ EXECUTIVE SUMMARY The intent of this report is to evaluate the condition and load rating of the Roberts Road Bridge over Los Gatos Creek and propose alternatives for future use of the existing structure or the need for replacement. Alternatives must consider the deficiencies identified by field observations, bridge load capacities based on the record drawings, foundation scour susceptibility, seismic vulnerability, roadway geometrics and the expected service life of the structure. The existing bridge is an 84' long, two span cast-in-place concrete T-beam structure supported by tall abutment walls and a central pier wall. The pier wall and abutments are founded on spread footings with shallow depths below the existing ground surface. The following areas of deficiency are the principal factors that need to be considered in preparing recommendations for the existing stricture or the need for its replacement: 1. Constructed in 1918, the remaining service life of the structure is very limited without substantial repairs and load limits (traffic weight restrictions). 2. The central pier supported on a shallow spread footing is located at the side of the low flow channel. These conditions make the pier wall very susceptible to scour, which could result in the loss the bridge structure and blockage of the creek channel under high flow conditions. 3. The roadway alignment and "the narrow bridge width limit the roadway to one way traffic alternating with stop signs at each end of the bridge. Based on these conditions and the costs associated with addressing these deficiencies, the following alternatives are presented with rough order of magnitude cost estimates: 1. Limit the existing structure to a load rating of 12 tons and retrofit the central pier wall to resist scout under critical stream flow conditions. Repair concrete spalls and cracks. This load rating should extend the service life of the bridge but much higher than average maintenance costs should be expected because of the structure's age. Load ratings are generally difficult to enforce and even higher maintenance costs should be expected to account for this. Estimated Cost = $1,000,000 (initial cost for scour retrofit/channel reconstruction and spall/crack repair; long term maintenance costs not included) 2. Remove the existing structure and construct a one or two span structure. The available options for a replacement structure range from a simple concrete girder bridge to an architecture that mirrors the original bridge type in either a one or two span configuration. Estimated Cost, single span = $1,300,000 (long term maintenance costs will be very low) 1 Estimated Cost, two span = $1,400,000 (long term maintenance costs will be higher) Cost estimates for these alternatives, beyond a rough order of magnitude estimate, are beyond the scope of this report. Such estimates would require farther investigation of the channel hydraulics, subsurface conditions and roadway geometrics. The existing bridge can be opened for automobile/light truck traffic with negligible impact to the service life of the structure. The scour critical condition of the bridge warrants remedial measures to protect the bridge, supported utilities and the immediate area. ,2 PROJECT BACKGROUND The existing structure on Roberts Road in Los Gatos, California is a two span continuous concrete bridge over Los Gatos Creek. The concrete bridge was built in 1918 with two equal spans. EXISTING CONDITIONS Bridge Stricture: Spans: two 42'-3" spans, total length = 84'-6" ® Concrete slab; average structure depth = 7.5" with 2"asphalt wearing surface 0 Two rectangle concrete girders (18"X49") spaced at 10' supporting the bridge deck. Numerous utilities hung from each side of the bridge deck Bridge Roadway: 0 Roadway width = 20' (clear distance between barriers) 0 Barriers: concrete parapet walls (10" wide and 36" tall) 0 One traffic lane only Existing Conditions: 1. The concrete deck slab is poor condition. Spalls and reinforcement are visible at the underside of the deck slab. Deficiencies at the top of the deck slab, if any, could not be verified due to the asphalt overlay. 2. The two primary longitudinal concrete girders are in fair condition. A large spall at the southern longitudinal edge beam has exposed the main reinforcement for this beam. 3. There are several large rock pockets at the abutments and the sides of the central pier wall. No reinforcement is exposed by these deep pockets. 4. The concrete barrier is spalled in several locations resulting in exposed reinforcement and reduced traffic impact resistance. 5. Cracks are visible in the long wingwalls on the western end of the bridge. 3 SCOUR POTENTIAL The existing concrete pier wall is founded on a spread footing at the side of the low flow channel. At high flow stages (Elevation 320' according to the Santa Clara Valley Water District) the pier wall is situated in the center of the channel and it is likely that the pier will catch debris brought downstream by the creek flow. At the time of our inspection, the bottom of footing based on the record drawings is approximately 5.5'feet below the channel invert at the pier location. This is very limited scour protection for a spread footing foundation system. These conditions result in a pier wall that is susceptible to scour and undermining. The undermining of the support of the center portion of the bridge could result in collapse of the bridge and blockage of the creek flow under high water conditions. The bridge supported sewerline, waterline and other utilities could be ruptured or lost under this scenario. Scour risk increases with structure age due to long term degradation of the streambed. Upstream improvements may increase or decrease scour rates but overtime scour depths will increase. Based on the original drawings and recent field observations, general scour is estimated at 4'-6" below original grade at the time of bridge construction. Local scour may significantly exceed this during a flood event. Scour holes due to local scour are often only a short-term condition associated with flood events. It is the combination of general and local scour that produces a scour critical condition at the Roberts Road Bridge center pier. Due to the risks and level of susceptibility to scour, the central pier should be retrofitted to increase its scour resistance. This could be accomplished by the driving of sheetpiling around the pier footing. Driving or vibrating the sheetpiles into place under low headroom conditions is generally a costly repair. Providing access for equipment will also impact the channel environment. Alternatives such as channel invert protection will produce even more channel disruption during construction and may be unacceptable to the regulatory agencies as a repair alternative. 4 BRIDGE LOAD RATING The bridge superstructure consisting of a pair of concrete T-beams was evaluated for flexure and shear to establish a bridge load rating. Table 1 provides a comparison of the moment capacities of a T-beam and the factored moment induced by an HS20-44 design vehicle. Bridge ratings can be developed based on these calculated capacities. Table 1- SUPERSTRUCTURE FLEXURAL DEMAND VS. CAPACITY 7 Positive Moment (kips-ft) Negative Moment (kips-ft) Capacity 924 881 Demand 1894 1862 Deficit (kips-ft) -970 -981 I Bridge load ratings are based on the AASHTO Manual for Condition Evaluation of Bridges, 1994 with Interim Revisions. The bridge was load rated at both the Inventory and Operating levels. The results are summarized in Table 2. An inventory level load rating defines a live load which can safely utilize the bridge for an indefinite period of time. An operating level load rating defines a maximum permissible live load to which the bridge maybe safely subjected. Allowing unlimited numbers of vehicles to use the bridge at Operating level would shorten the life of the bridge. Table 2 - BRIDGE LOAD RATING Level Rating Factor HS Truck Max.Load (tons) Inventory Rating Level 0.203 7.3 Operating Rating Level 0.338 12.2 Posting and enforcement of these load ratings will extend the life of the structure. The operating rating level will extend the seivice life of the bridge but much higher than average maintenance costs should be expected because of the structure's age. The inventory rating level will extend the service life of the bridge where factors other than traffic loading will determine the structure's ultimate service life (long term maintenance costs, channel efficiency, creek bank erosion, etc.). A load rating of 12 tons is recommended for the Roberts Road Bridge. This load rating should extend the service life of the bridge but much higher than average maintenance costs should be expected because of the structure's age. Load ratings are generally difficult to enforce and even higher maintenance costs should be expected to account for this. As a general basis for comparison: Garbage truck weight: 25 tons (this is sometimes exceeded by a full track) Delivery truck: 18 tons Large SUW: 4.5 tons 5 BRIDGE REPLACEMENT ALTERNATIVES Due to critical scour potential of the existing bridge pier, a bridge replacement alternative should be considered. Removal of the existing structure and construction of a one or two span structure can address the existing deficiencies at the site. The available options for a replacement structure range from a simple concrete girder bridge to an architecture that mirrors the original bridge type in either a one or two span configuration. A single span bridge will eliminate the mid-channel pier wall and eliminate the scour risk and channel maintenance associated with stream carried debris. For these reasons it is probable that the Santa Clara Valley Water District (SCVWD) would strongly favor a clear span structure especially since freeboard for the 100-year flow is not critical with a deeper single span structure (Top of bridge deck elevation = 335', 100-year water surface elevation = 320'). Removal and construction work will disturb the creek channel to the point where some bank protection will be required especially in consideration of the existing steep banks on the west side. Storm drain outfalls would be addressed as part of this channel bank protection. A replacement structure will allow for the realignment of the roadway to improve the traffic safety with increased sight distance and larger radius horizontal curves. Utilities supported by the structure can be placed within the structure and out of view. Accommodations for future utilities are easily provided through the bridge structure. The impacts of a replacement structure would require further evaluation of environmental issues, channel restoration measures, and traffic, geotechnical and hydraulics issues. 6 BIGGS CA.RDOSA ASSOCIATES, INC. Bridge North Elevation Bridge South Elevation BIGGS CARDOSA ASSOCIATES, INC. Bridge Deck OwmapEftsm Deck Spalls and Corrosion of Reinforcement BIGGS CARDOSA ASSOCIATES. INC. E.a Curb Beam Spalls and Corrosion of Reinforcement Abutment Concrete Spalls BIGGS CARDOSA ASSOCIATES, INC. ~WF a ~H a Bridge North Elevation Bridge South Elevation BIGGS CARDOSA ASSOCIATES, INC. Bridge Deck a B Deck Spalls and Corrosion of Reinforcement BIGGS CARDOSA ASSOCIATES, INC. Curb Beam Spalls and Corrosion of Reinforcement MIN f.uu!~r k Al. Abutment Concrete Spalls . Message Page 1 of 2 Patsy Garcia - Note of Thanks for the Roberts Road Bridge Closure From: "Julene Dee Pief ` ° To: <parks@losgatosca.gov>, <manager@losgatosca.gov>, <police@losgatosca.gov> Date: 3/25/2005 7:43 PM Subject: Note of Thanks for the Roberts Road Bridge Closure Hello there, I am writing to thank you and the Town Council for making the decision to close the Roberts Road Bridge and in doing so, eliminating some, but not all of the "cut through" traffic Roberts Road was experiencing when the bridge was open. In the months leading up to the closure, we experienced the following dangerous traffic conditions on a daily basis: • Vehicles consistently exceeding the speed limit on Roberts Road • Vehicles consistently running the stop signs at both sides of the bridge • High volume of "cut through" traffic traveling from University Ave. to Blossom Hill and vice-versa to avoid the light and intersection at University and Blossom Hill Since the bridge has been closed, we still have a fair amount of local traffic, and some cut through traffic going down Roberts Road and through Oak Rim Way, even though this is a very windy and inefficient route. The speed of traffic has diminished, although we do have occasional speeders. We do not see the traffic accelerating down the hill because the only alternatives at the end are 90 degree turns either on to Brickway or on to Oak Rim Way. ' Before the bridge was closed, there was an unsafe condition for pedestrians on Roberts Road. We have no sidewalks and the street narrows approaching the bridge. Many of the pedestrians are children walking to and from Fisher school, and so many times I have seen near misses by drivers not paying attention or in a hurry. Now, we have a pleasant walking street, where the students attending Fisher can walk without the volume of speeding traffic to contend with. Recently there was a home for sale in the neighborhood and the realtor showing the home mentioned to several prospective buyers that the bridge was planned to be re-opened. I questioned where he had heard this, but did not get a firm answer. I hope this is not the case and that the closure will remain. The benefits of the closure really far outweigh the slight inconvenience it causes. I have lived on Roberts Road for 28 years and I must say, the closure of the bridge is, in my opinion, one of the best things that has been done for this neighborhood since I've lived here. I would encourage you to adhere to the closure and make it more permanent. If there are any plans to re-open the bridge, could you please let the residents know, so we can provide our input. Many thanks, Julene Dee Pief i file://C:\Documents%20and%2OSettings\pgarcia\Local%2OSettings\Temp\GW}OOOOl.HTM ATTACHMENT 3