According to Article 4 1 of the Bidding Law of People's Republic of China (PRC), the bid of the successful bidder shall meet one of the following conditions: it can meet all the comprehensive evaluation standards stipulated in the bidding documents to the greatest extent; Can meet the substantive requirements of the tender documents, and the evaluated bid price is the lowest, except that the bid price is lower than the cost.
In addition, Article 29 of the Interim Provisions on Bid Evaluation Committees and Methods issued by seven ministries 12 also clearly stipulates that bid evaluation methods include the lowest evaluated bid price method and the comprehensive evaluation method.
Bid evaluation methods are generally divided into two categories: comprehensive evaluation method and evaluated lowest bid price method. The difference between them can be seen from the table 1
According to table 1, for a complex project like Nanjing subway project, the tenderee mainly considers not the price, but the bidder's quality, technology, reputation and professional knowledge, so it is necessary to adopt the comprehensive evaluation method.
2 Comprehensive evaluation method
2. 1 The meaning of comprehensive evaluation method
Comprehensive scoring method is a kind of bid evaluation method that scores the quality, technology, staffing, construction period, price, reputation and performance of bidders' technical and economic bids according to relative weights, and uses comprehensive scores to measure whether the bidding documents meet the evaluation standards stipulated in the bidding documents to the greatest extent.
The bid evaluation committee quantifies all bid evaluation factors according to the same basis or standard specified in the tender documents, and then weights the quantitative results of the technical part and the economic part to calculate the comprehensive bid evaluation price or comprehensive bid evaluation score of each bid. The bidder who meets the comprehensive evaluation criteria stipulated in the tender documents to the greatest extent is the candidate for winning the bid.
2.2 Evaluation process of comprehensive evaluation method
The evaluation process of comprehensive evaluation method for Nanjing subway project is generally divided into two stages:
(1) stage 1 is the first trial. The tender working group will "clear the tender", conduct a preliminary examination of the tender of the tenderer, and exclude bidders who have not responded to the tender documents and have significant deviations in the tender offer.
(2) The second stage is detailed review. The bid evaluation committee composed of the owner's representative and relevant technical and economic experts will conduct evaluation on the basis of initial evaluation. The bid evaluation committee quantifies the evaluation factors according to the evaluation method determined in the bidding documents, and then weights the quantification results to calculate the comprehensive evaluation score of each bid.
The bid evaluation committee ranks the bidders according to the final comprehensive evaluation score, and the owner generally determines the winning candidate ranked first as the winning bidder on this basis. If the winning candidate ranked first gives up winning the bid, fails to perform the contract due to force majeure or fails to submit the performance bond within the time limit specified in the tender documents, the winning candidate ranked second can be determined as the winning bidder.
3 Nanjing subway comprehensive evaluation method design
3. 1 Theoretical basis of comprehensive evaluation method design
3. 1. 1 game theory
The whole bidding process is a game process between bidders and owners, bidders and bidders. When bidding, each bidder does not know the opponent's decision when making his own decision. He can only work out the tender that the owner may accept according to his own actual situation and the prediction of the whole market, and consider the possible decisions of other bidders, and send it to the owner or agent in a sealed form, so as not to let his quotation and other information be known to the opponent. Only at the time of bid opening can all the information in this respect be disclosed to determine who won the bid. Therefore, in general, bidding belongs to a typical static game with incomplete information-Bayesian Nash equilibrium. The design of bid evaluation method in bidding is actually the mechanism design in game theory, and the design of scoring method in bidding can be guided by the relevant principles and methods in game theory.
3. 1.2 Principal-agent theory
The project owner established the principal-agent relationship with the winning bidder through bidding. In order to better achieve the goals of quality, investment, construction period, health, safety and environmental protection, the owner needs to effectively motivate the bidders. Therefore, the design of scoring method needs to use the principal-agent theory to solve the problem of how to motivate, and must meet the incentive compatibility constraints.
Incentive compatibility constraint means that the designed mechanism (i.e. scoring method) should enable the bidder to actively choose the behavior that the tenderer wants, so as to ensure that the mechanism can achieve the expected goal of the tenderer and avoid the unintended result of the tenderer. According to this constraint, Nanjing Metro Project encourages enterprises with high quality and good reputation, and gives such enterprises higher scores in scoring methods, so that contractors can strive to improve the project quality, ensure the construction period and achieve the goals expected by the owners.
Accordingly, in the design of comprehensive evaluation method, according to the engineering nature, characteristics and technical content requirements, the evaluation factors and weights of technical and economic targets, as well as the benchmark scores related to economic targets are stipulated, so it can well meet the incentive compatibility constraints in the above mechanism design. In addition, there are various mathematical methods and statistical methods used for comprehensive evaluation.
3.2 Determination of bid evaluation factors and weights
The comprehensive evaluation method is basically adopted in the bidding of Nanjing subway project, and the bidders are selected according to their comprehensive evaluation scores Ai:
[Ai]=[α] [Bi]+[β] [Ti]
Among them, [bi] refers to Bidder I's technical bid (including construction organization design scheme and technical points, difficulties and countermeasures analysis, selection and supply scheme of main materials and equipment, bidder's personnel, equipment and technical force input in this project, quality, safety, civilized construction and other guarantee measures, construction period, technical scheme optimization and rationalization suggestions, company reputation and related engineering performance, bidder's defense, etc.). ); [α]-weight of technical target; [ti]- economic bidding of bidder I; [β]-the weight of economic goals.
Because of the one-off feature of project implementation, there are no two identical projects. According to the difference of each project, different scoring methods need to be formulated. Therefore, according to different technical difficulties and different scope of work, Nanjing subway project determines different weights to highlight the different requirements of the owners for each project.
(1) civil architecture. The technical part accounts for about 60 points, mainly including the construction organization design scheme and technical points, difficult analysis and countermeasures, the selection and supply scheme of main materials and equipment, the bidder's investment in personnel, equipment and technical force in this project, the guarantee measures such as quality, safety and civilized construction, the construction period, optimization and rationalization suggestions of technical scheme, the company's reputation and related engineering performance, and the bidder's defense; The economic part accounts for 40 points, mainly including the bid quotation and the rationality of the quotation.
(2) design. The technical part accounts for about 75 points, mainly including optimization design, personnel, qualification, performance and rationalization suggestions; The economic part accounts for 25 points, mainly including the bid quotation and the rationality of the quotation.
(3) consultation. The technical part accounts for about 90 points, mainly including work outline, related research, rationalization proposal and overall coordination plan, performance and personnel. The economic part accounts for 10, mainly including the bid quotation and the rationality of the quotation.
(4) supervision. The technical part accounts for about 80 points, mainly including reputation, qualification, staffing, rationalization suggestions and defense; The economic part accounts for 20 points, mainly including the bid quotation and the rationality of the quotation.
(5) Equipment procurement. The technical part accounts for about 50 points, mainly including advanced design, reliability, advanced production and reliability, quality assurance system and measures, supply plan and measures, qualification, performance, maintenance and service commitment. The economic part accounts for 50 points, mainly including the bid quotation and the rationality of the quotation.
(6) Installation and construction. The technical part accounts for about 60 points, mainly including the construction organization design scheme and technical points, difficult analysis and countermeasures, the selection and supply scheme of equipment and materials, the bidder's investment in personnel, equipment and technical force in this project, the technical scheme optimization and rationalization suggestions, the company's reputation and related project performance, the bidder's defense, debugging scheme, etc. The economic part accounts for 40 points, mainly including the bid quotation and the rationality of the quotation. See figure 1 for the economic and technical weights of each bidding project.
In addition, the comprehensive evaluation method of Nanjing subway project is characterized by paying attention to people, considering the factors of bidders' defense in the bid evaluation method and setting other weights all reflect this point.
Generally speaking, when determining the scoring weight of Nanjing metro project according to different bidding projects, the scoring methods of design, consultation and supervision should consider more technical and human factors, while the material procurement should consider more quotation, supply scheme, maintenance and service commitment, and the installation and construction should be specially added to the debugging scheme.
By determining different weights for different projects, bidders' bidding behavior can be reasonably guided and the owners can realize their intentions well.
3.3 Determination of scores
For the technical part, when determining the score, the experts of the Bid Evaluation Committee will score according to the method specified in the tender documents, and then on the basis of preliminary evaluation, the score will be weighted and averaged according to the relevant contents in the tender documents and the bidder's defense.
For the economic part, score according to the deviation between the bidder's quotation and the benchmark price, the rationality of the quotation (including the rationality of the main unit price and the rationality of the quotation composition) and stability. It is particularly important to note that although the weights are sometimes the same for different bidding projects, the specific scoring methods are different for the specific requirements of different bidding projects; For example, when inviting bids for civil buildings, the bid price lower than the benchmark bid price 1%~3% is determined as the reasonable low bid; When inviting tenders for station decoration, the bid price which is 2%~5% lower than the benchmark bid price is determined as the reasonable low bid.
3.4 Specific application examples
Taking the bid evaluation of a civil engineering in Nanjing subway as an example, the comprehensive evaluation method is illustrated, and the full mark of bid evaluation is 100.
(1) Technical part (60 points).
Mainly includes: selection of main materials and equipment and supply scheme (14 points); Construction organization design scheme and technical points, difficulties analysis and countermeasures (24 points); The bidder's investment in personnel, equipment and technical force in this project (6 points); Company reputation and related engineering achievements (5 points); Suggestions on optimization and rationalization of technical scheme (2 points); Quality, safety, civilized construction, time limit for a project and other guarantee measures (2 points); Bidder's defense (7 points).
(2) Economic part (40 points).
The bid evaluation factors mainly include:
(1) Bid quotation (30 points). Benchmark price = arithmetic average of bidders' quotations after removing the highest and lowest quotations. The bid price lower than the benchmark bid price 1%~3% is a reasonable low price, with a score of 30 points. On the basis of winning the bid at a reasonable low price, 0.5 points will be deducted for each increase of 1% and each decrease of 1%. The middle number is calculated by interpolation, and two digits will be reserved after the decimal point.
(2) Rationality of tender offer (10). Among them, the main unit price rationality is 4 points, and the quotation rationality is 6 points.
The main unit price is an important unit price in the bill of quantities, and the bid evaluation ranking after bidders' preferential treatment is calculated according to the following formula:
Where di refers to the position of the unit price in the review; Pi -- the bid evaluation unit price after the preferential treatment of the bidder; Ti-the unit price of each bidder after preferential treatment; N-number of bidders; α-the downward fluctuation range of the benchmark price determined by the owner (2%). Fraction distribution: D∈(- 10%~0), fraction100%; D∈(-20%~- 10%), with a score of 80%; D∈(-30%~-20%), scoring 70%; D∈(0~+10%), with a score of 80%; D∈(+ 10%~ +20%), with a score of 70%.
Score according to the proportion of units falling in each interval, and then multiply the total score of five intervals by the weight of the total score of the main unit price, which is the final score of the rationality of the main unit price. Those exceeding -30% or +20% will not participate in the grading.
The evaluation of the rationality of quotation is divided into four sub-items, namely, whether the work content is complete, the rationality of charging, the clarity of unit price analysis table, and the rationality of labor, materials and machine consumption.
Among them, whether the work content is complete, including quotation description, bill of quantities summary table, bill of quantities, comprehensive unit price analysis table, lump sum project quotation calculation table, steel bar and cement content table, and whether the understanding is correct; The quotation indicates whether there is a reservation, etc. The rationality of fees includes whether the relevant rates are reasonable or not, and whether they exceed the relevant government regulations on cost management; The cost of the main combination price items is basically reasonable. The clarity of the unit price analysis table includes whether the contents of the unit price analysis table are complete; Whether the unit price in the unit price analysis table is consistent with that in the bill of quantities, etc. ; Whether the unit price analysis is based on the list unit of measurement or the quota unit of measurement; Whether the material adjustment lists the material name, quantity and unit price. Rationality of labor, materials and machine consumption. Including whether the consumption of labor, materials and machinery is basically reasonable.
The full mark of each scoring item is 1.5, which is divided into the following three grades according to the degree of conformity with the evaluation content: general 0~0.5 (including 0.5), good 0.5~ 1.0 (including 1.0), and excellent1.0 ~/kloc.
From the above, it can be seen that the comprehensive bid evaluation method of Nanjing Metro Project is scientific and reasonable, completely in line with the legal and theoretical basis mentioned above, and can enable bidders with high quality, good reputation, strong ability and reasonable quotation to win the bid.
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