|
DESIGN MEMORANDUM NO. 5-98 TO: Chief District Engineers FROM: John B. Sacksteder, P.E. DATE: February 11, 1998 SUBJECT: Traffic Management
The amount of construction required on our existing major highways, including our interstates has been increasing astronomically for the last several years. In a presentation before the legislature a few months ago, Secretary Codell advised that Kentucky’s emphasis for the future will be to maintain the integrity of our existing roadways with limited new construction. With the emphasis on reconstructing or rehabilitating our existing roadway systems, impacts to the public traffic operations increases. While recognizing the need for the roadway maintenance, the public demand and involvement gives an increasing voice for minimizing delays to and increasing safety for the motorist. Similarly the construction workers have increasing conflict with vehicles as a result of more projects adjacent to existing roads and greater traffic involved. Our Designers therefore must be charged with developing the most efficient and safe methods of traffic management within cost parameters. Traffic should be inhibited as little as possible during construction with an identical number of temporary lanes matching the existing facility, whenever possible. Clear and positive traffic control is needed with adequate signing and special devices such as message boards and flashing arrows provided to clearly guide the motorist through the construction zone. When required, provisions for pedestrians must also be considered. The use of flaggers for traffic control should be a last resort consideration and should generally only be used for some short term basis. For the past few months, the Divisions of Highway Design, Traffic, Operations, and Construction in conjunction with members of the Kentucky Association of Highway Contractors and the Federal Highway Administration have investigated methods to improve traffic operations during construction. This has resulted in a number of new strategies or increased emphasis on previously employed methods and includes changes in construction bid items and methodology. Included in these thoughts are an increased emphasis on the Designer to weigh the requirements and interests of construction against the public involvement. Following is a discussion of new directions and considerations that the Project Development Teams (PDT) will have to consider and implement as deemed necessary with each project.
TRAFFIC CONTROL PLAN Effective with the publication of the 1998 Standard Specifications for Road and Bridge Construction, the standard notes currently included as Exhibit 03-10 in the Highway Design Manual will become part of the Standard Specifications. The sole exception to this is the note for pavement edge drop-off currently shown on page 7 of the standard notes. This note will become a general note on the computerized listing of notes that will be able to be called for when appropriate by its computer coded number. Exhibit 03-10 will become void with the release of the 1998 Standard Specifications book. With this change, the traffic control plan will be reduced to only the specific phasing required by the particular project. This phasing will now be required only to be shown in the plans and will no longer require a written submittal. Drawings and notes are to be developed and placed on traffic control sheets within the plans or if limited notes are required, these notes may be placed on the General Notes sheet for the project. The approval of the Traffic Control Plan will be the responsibility of the Project Development Team (PDT) (see Design Memo 4-98). No submittal of the Traffic Control Plan to Central Office will be required. It will be necessary for the PDT to agree upon an appropriate documentation for each plan that will consist of the signatures of at least the District Branch Managers for Pre-Construction, Construction, and Traffic and FHWA on interstate or other special projects. This documentation must be contained in the file folder retained by the District. Approved plans involving road or lane closures must be sent to the Traffic Control Coordinator in Central Office at least 90 days in advance of the project letting with an indication of expected dates for such closures. The Traffic Control Coordinator is currently posting all information with the American Automobile Association and making it available to the Public Information Office to make necessary news bulletins in local newspapers or other media. The PDT should still consider making critical information available through special sources, such as pamphlets to be handed out in public locations. The Traffic Control Plan (TCP) is to be developed using the Standard Specifications and Standard Drawings as a basis. Only those requirements not provided in the Standard Specifications required for maintaining and controlling traffic are to be written into the TCP. The TCP will clearly indicate all required phasing, method of traffic control, and any time or construction limitations that will be placed on the contractor. Attention should be given to developing strategies that will limit impact to the traveling public. As much as possible, the existing number of lanes should be attempted to be maintained throughout a construction project, particularly on the interstates and other major routes. Where it is determined that lane restrictions are necessary, decisions on the best manner to assure limited closures must be made. Considerations for these decisions will include restricting work during peak periods of traffic flow on the route and demanding the use of nighttime construction. The TCP should also take into account other adjacent roadway sections that may be under construction and avoid conflict between competing phases of adjacent projects. BID ITEMS A number of new bid items have been included in the Standard Specifications that relate to traffic control. The new bid items included are for:
The Designer should read the Standard Specifications and familiarize themselves with the requirements for each of these new bid items. Section 112 of the Standard Specifications specifically involves maintenance of traffic issues and may reflect some changes in how items are bid beyond the new items shown above. One major change is a requirement that all temporary or permanent signs required for a project will be bid on a square meter basis. This includes those signs shown routinely in the Standard Drawings. A lump sum bid item for "MAINTAIN AND CONTROL TRAFFIC" shall be included for every project with no exceptions. The PDT is now responsible for developing all permanent and temporary striping plans including the use of pavement markers required for each project. Adequate striping and other traffic control devices shall be determined for each phase of a contract. Other traffic control devices, such as message boards and flashing arrows, must also be identified and bid in adequate numbers for each project.
INNOVATIVE BID PROCESSES The designer should carefully consider the impacts of construction on the motorists. The use of innovative bid processes should not be routinely utilized. These processes are recommended where the public will experience extreme disruption and delays and where time of completion of a project or an individual phase is particularly critical. Should the designer choose to use this methodology, a well-developed traffic control plan with all phases well thought out and developed is mandatory. The rates applicable in each of the following described processes is based on established practices for benefit/cost ratios based on road user delay costs. The Division of Multi-modal Programs may help in the development of these ratios. A) INCENTIVE/DISINCENTIVE Liquidated damages are commonly charged against all project completion dates. Liquidated damages may also be charged in excess of rates established in the Standard Specifications when deemed appropriate and when the expected impacts to the public may be considered to be greater than the damages established by specification. Liquidated damages may also be charged against individual phases of a contract, particularly when the phase is deemed to be particularly critical to the operation of the highway or for the safety of the motoring public. However, the use of incentives/disincentives described in the next paragraph are probably a more effective method to handle the impacts of individual phases. Incentive/disincentives are commonly used on projects with high traffic volumes and involving construction requirements that will greatly restrict or even shift traffic away from the existing facility. The incentive/disincentive contract compensates a contractor the same per day for early completion of a contract or phase as he is penalized for late completion. If for some reason it is decided that a different incentive and disincentive cost is to be applied, the incentive rate shall not be greater than the disincentive. The amount applied for the incentive/disincentive is based on estimates of such items as traffic safety, traffic maintenance, and road user delay costs. Incentive/disincentives are generally applied only to work that directly affects the motorist and therefore frequently does not replace normal contractual liquidated damages. The incentive/disincentive provision should be of an adequate amount to motivate a contractor to complete the project or phase ahead of schedule. In considering the use of incentive/disincentives or any of the other innovative practices that follows, the Designer must assure that the work zone will be free of delays that will be beyond the contractor’s control; i.e., utility work. The use of incentive/disincentive contracts will normally be based on a calendar day completion rather than a work day; therefore any contractual language that suggests a conflict with the times established for the incentive/disincentive must be addressed or waived. This includes the end of construction seasons or other seasonal construction limitations and impacts by holidays. Incentive/disincentive contracts should take into account a contractor working beyond a normal five day/week on eight hour shifts to accomplish the work. Expectancy for this type of work would be for a much greater effort to be made by the contractor to complete the project or phase.
B. COST PLUS TIME BIDDING (A+B BIDDING) Cost plus time bidding is utilized where it is desired for the contractor to develop the most timely method of completing a project. Bidding is developed for this type of project by the formula A+B=C where A = the traditional bid for contract items and is the actual contractual amount and B= the total number of calendar days required to complete the project times a road user cost/day established by the DPDT. The contract is then awarded based on the total bid C made by the contractor. A disincentive is then placed in the contract based on the established road user costs which is placed in effect if the number of days bid by the contractor is exceeded. Similarly an incentive cost is usually included in the contract to reward the contractor if the work is completed earlier than the time bid. A+B bidding can be utilized for specific major phases of a contract rather than the entire contract, if desired. Cost plus time bidding is effective when multiple bidders will be involved. If the designer determines that there is a likelihood that a single bidder will be involved for a project, it is more appropriate that one of the other two described innovative bidding processes be utilized for that project. C. LANE RENTAL The lane rental concept is used to encourage contractors to minimize road user impacts during construction while permitting him the greatest flexibility in deciding the appropriate time frames for lane closures and restrictions. In this concept, there is no specific bid item for lane rental. Rather the award of the project is based solely on the contractor’s estimated bid price. However, a provision for a lane rental fee assessment based on a road user cost is included in the contract and is assessed against the contractor’s contract on his monthly contract payments. The fee is assessed for the time that the contractor occupies or obstructs any part of the roadway or may be specific to certain segments of the contract. The rental fees may be based on weekly, daily, hourly, or even fractions of an hour. Lengths of lane closures may also be taken into account. Greater fees may be charged for certain times when traffic may be greater; i.e., during rush hours when hourly rates are bid or during holidays when a daily rate is bid. Restrictions on lane closures for special events or holidays may still be made, but generally the Department should limit the restrictions placed on the contractor and leave the decision of the best time frames for his actions within the contractor’s decision making. Obviously CPM scheduling of this type of an operation is very critical for the contractor to assure the least economic impact to his contract and for the Department to completely understand the schedule on which he will complete his work. Neither the Department nor the contractor will give any indication in the project bid as to the anticipated time for which assessments may occur. This concept should be particularly considered on projects where the traveling public will be most impacted. Major urban projects are prime candidates. The intent of lane rentals is to encourage contractors to schedule their work to keep lane restrictions to a minimum, both in terms of length of duration and the number of closures or other obstructions that occur. Pre-bid Conferences should be considered whenever innovative bidding methods are utilized so the contractor can best understand the established restrictions, the time frames involved in the overall project and for specific phases that require extra control and effort. CONSTRUCTION PRACTICES A new Special Provision will be forthcoming shortly for "Portable Traffic Control Systems (PTCS) for Work Zones". This system is a wireless communication system that provides the motorist with advance warning messages of reduced speeds, delays, alternate routes and aids in the merge of traffic in restricted lane conditions. The system consists of electronic sensors that can monitor the speed of traffic in the work zone and based on drops of speed can provide pre-set messages in advanced warning signing. Within the work zone, the sensors identify backups and through message boards advises the traffic to merge in advance of the restricted condition. As traffic backs up further, the merge point shifts backwards and the signs within the backup indicate that no merging is permitted within the restricted area. This moves traffic through the zone in the fastest and safest manner. Enforcement of this no merge area is required to ensure that the efficient flow of traffic is optimized. This system should be utilized on major projects with a high ADT, particularly interstates, where reduced lanes or restricted lane widths occur that are likely to result in considerable traffic delays or stoppages. A lump sum bid for the system will be provided when the Designer decides to call for it on a project. As indicated above, enforcement is frequently needed in work zones to assure the safety of construction workers, to maximize construction zone safety, and to maintain the motorist’s compliance with speed zones established with the project construction. Secretary Codell has determined that as staffing permits, officers in the Department of Motor Vehicle Regulation may aid the Department in policing construction work zones. The DPDT should contact this Department to advise of potential needs of officers and to determine the officer’s availability for the project. The Federal Highway Administration has indicated that the cost required for the use of officers, including the Vehicle Regulation staff, is eligible for federal funding. Direct charges or inter-account billing may be utilized for the costs of the Vehicle Regulation officers. The method of charging staff will be developed as required. The Transportation Research Board completed a series of studies that measured the actual flow of traffic in work zones. The following chart is an indication of expected impacts to traffic flow when lane reductions occur:
The average capacities shown are for the expected total traffic on the open lanes in the construction zone and traffic per vehicle lane. As shown in these charts and as should be expected, the more merging that is required in a construction the less traffic can pass through the work area. These numbers may be utilized for a rough prediction of expected delays that may be encountered as a result of lane closures. Obviously, having the presence of ramps within the construction zone increases the impact to the traffic flow. Considerable discussion of lengths of lane closures that may be permissible and the impacts to traffic delay occurred during the process team’s review. However, it was basically decided that the impact to traffic occurs at the merge point. As traffic flows into the reduced lanes, traffic counts as shown above may be expected. Length of closure has no impact on the amount of traffic that can pass any roadway segment as the reduced lanes controls the number of vehicles which may pass. However, lengthy lane closures - particularly if no apparent work is visible to the motorist - are frustrating to travelers and should be avoided. Lengths of closures should be established based on a reasonable time frame to accomplish work activities. As discussed previously, lane rentals based on a per mile basis of closure may be an effective method to permit the contractor the maximum closure he deems feasible in an established time frame. Complete closures of roadways or ramps may be considered to finish construction in the shortest time frames possible where alternate routes exist and should not be ruled out as possible alternates. Another consideration would be to permit closures on only one side of the highway at a time. An appearance that work is occurring on one side while the other side is restricted with little activity can also be discouraging to the motorist. Two-lane, two-way operation (TLTWO) on one roadway of a normally divided highway shall be utilized only after careful consideration of other available methods of traffic control. On the interstates TLTWO will require the use of median barrier wall for positive separation of traffic. On other roadway systems , the use of median barrier wall should always be a first consideration. Generally, a TWTLO should be used on urban type streets or other low speed operations and where the driver can see the transition back to normal one way operations. There may still be some reason why the PDT may choose to utilize TWTLO in circumstances other than those cited without the use of barrier wall. In these cases, the lanes shall be separated by tubular markers, which shall be paid for on an each basis. In that past, there has been a general recommendation that a raised bituminous median would be utilized on which the markers would be mounted. It has now been determined that the raised bituminous median is not desirable and should be eliminated from use on future projects. All measures discussed in this memo should be put into effect immediately. Items applicable to the 1998 Standard Specifications are to be effective with the April, 1998 letting. However, if the Designer wishes to utilize any of the items included in that document prior to that date, it may be added by special note and is encouraged. JBS:jad
|
|
|