TRANSPORTATIONRESEARCHPARTEPERGAMONTransportationResearchPartE38(2002)439-456www.elsevier.com/locate/treMeasures for evaluating supply chain performancein transport logisticsKee-hung Lai a,, E.W.T. Ngai b, T.C.E. ChengaDepartment of Shipping and TransportLogistics,TheHongKongPolytechnicUniversity,Hung Hom,KowloonHongKongbDepartment of Management,The HongKong Polytechnic University,Hung Hom,Kowloon,HongKongReceived 26 November 2001; received in revised form 13 March 2002; accepted 5 April 2002AbstractThisstudyaimstoinvestigatetheconstructof,and developameasurementinstrumentfor,supplychainperformance(SCP)in transportlogistics.Basedon the supplychainoperationsreferencemodeland variousestablishedmeasures,ameasurementmodelandameasurementinstrumentforSCPintransportlogistics are developed.A26-item SCP measurement instrument was constructed, reflecting service effec-tivenessforshippers,operationsefficiencyfortransportlogisticsserviceproviders,and serviceeffectivenessfor consignees.The empirical findings suggest that the measurement instrument is reliable and valid forevaluating SCP intransportlogistics 2002 Elsevier Science Ltd. All rights reserved.Keywords:Transport logistics; Supply chain; Construct; Performance measurement; Confirmatory factor analysis1.IntroductionThe emergence of the global economy and intensified competition have led many firms torecognize the importance of managing their supply chains for fast product introduction andservice innovations to the markets.For improved competitiveness, many firms have embracedsupply chain management (SCM) to increase organizational effectiveness and achieve such or-ganizational goals as improved customer value, better utilization of resources, and increasedprofitability (Lee, 2000).'Corresponding author. Tel.: +852-2766-7920; fax: +852-2330-2704.E-mail address: stlmlai@polyu.edu.hk (K.H. Lai).1366-5545/02/S-seefrontmatter2002ElsevierScienceLtd.All rights reserved.PII:S1366-5545(02)00019-4
Measures for evaluating supply chain performance in transport logistics Kee-hung Lai a,*, E.W.T. Ngai b , T.C.E. Cheng b a Department of Shipping and Transport Logistics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong b Department of Management, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Received 26 November 2001; received in revised form 13 March 2002; accepted 5 April 2002 Abstract This study aims to investigate the construct of, and develop a measurement instrument for, supply chain performance (SCP) in transport logistics. Based on the supply chain operations reference model and various established measures, a measurement model and a measurement instrument for SCP in transport logistics are developed. A 26-item SCP measurement instrument was constructed, reflecting service effectiveness for shippers, operations efficiency for transport logistics service providers, and service effectiveness for consignees. The empirical findings suggest that the measurement instrument is reliable and valid for evaluating SCP in transport logistics. 2002 Elsevier Science Ltd. All rights reserved. Keywords: Transport logistics; Supply chain; Construct; Performance measurement; Confirmatory factor analysis 1. Introduction The emergence of the global economy and intensified competition have led many firms to recognize the importance of managing their supply chains for fast product introduction and service innovations to the markets. For improved competitiveness, many firms have embraced supply chain management (SCM) to increase organizational effectiveness and achieve such organizational goals as improved customer value, better utilization of resources, and increased profitability (Lee, 2000). Transportation Research Part E 38 (2002) 439–456 www.elsevier.com/locate/tre * Corresponding author. Tel.: +852-2766-7920; fax: +852-2330-2704. E-mail address: stlmlai@polyu.edu.hk (K.H. Lai). 1366-5545/02/$ - see front matter 2002 Elsevier Science Ltd. All rights reserved. PII: S 1 3 6 6 - 5 5 4 5 ( 0 2 ) 0 0 0 1 9 - 4
440K.H.Lai et al. /Transportation Research Part E38(2002)439-456In his seminal work on competitiveness of firms, Porter (1985) identifies customer values andcoststo customersascritical elementstogain competitiveadvantagesforafirm.Themanagementof a supply chain encompasses these two elements, which together emphasize the importance ofgetting goods/services to customers at the right time, in the right place, under the right conditions,in the right quantities, and at the lowest possible costs. Porter (1985) emphasizes that, differen-tiation, one type of competitive advantage for a firm, is closely linked to the customer values ofthe product/service that can be delivered. Low cost, another type of competitive advantage, isreflected in the costs of theproduct/servicetothe customers.Christopher (1998)adds that a firmwould achievea competitiveadvantageby striving forexcellence inboth serviceand cost lead-ership.To this end, making proper performance measurement of a supply chain is necessary as itcultivates understanding between member firms in the supply chain for performance improvement(Dreyer,2000;FawcettandCooper,1998)Traditionally,thefocus of performance measurement has been on process operations withintheorganizational boundaries of a firm (ShortandVenkatraman,1992).In thecontextof SCM,performance measurement involves not only the internal processes, but also requires an under-standing of the performance expectation of other member firms in the supply chain, backwardfrom the suppliers and forward to the customers (Normann and Ramirez, 1993).Coordinationbetween thevariousparties in the supply chain iskeyto its effective implementation (Frohlich andWestbrook,2001).As SCM focuses on process management beyond organizational boundaries, there is a need tomeasure performance for the effective management of a supply chain.Harrington (1991,p.164)states that'If you cannot measure it, you cannot control it. If you cannot control it, you cannotmanage it. If you cannot manage it, you cannot improve it'. In fact, the lack of relevant per-formance measures has been recognized as one of the major problems in process management(Davenport et al., 1996) and the management of a supply chain (Dreyer, 2000). Because of thedifferent views on what should constitute supply chain performance (SCP), many firms havefound it dificult topracticeSCM (Beamon,1999).Amajor contributingfactor to this problem isthat, with multiple parties having different interests, it is difficult for firms to effectively evaluatethe performance of their activities on a supply chain-wide basis (Cooper et al., 1997).Conse-quently, firms in different parts of the supply chain tend to work to improve performance in thoseareas within their interest.To overcomethisproblem,they need a comprehensive overview oftheir supply chain activities and full appreciation of the impact of their performance on othermemberfirms in the supplychain.The objective of this study is to investigate the construct of, and develop a measurementinstrument for, SCP with a focus on the intermediary component, i.e., transport logistics, in asupply chain process. A measurement instrument is a collection of measuring items appliedcollectivelyto reveal a theoretical construct,e.g.SCP in transport logistics, which cannot beassesseddirectly(DeVellis.1991).Given the ambiguityin the literatureand the lackof em-pirically validated measurement instruments for SCP, this research objective is well justifiedwith the aim to extend SCM research to the transport logistics context.Weidentifythecomponents of sCP in transport logistics, develop the measurement items and instrument,evaluate their validity using empirical data, discuss the implications of the SCP construct, andprovide suggestions for using the validated measures in substantive research and practice intransportlogistics
In his seminal work on competitiveness of firms, Porter (1985) identifies customer values and costs to customers as critical elements to gain competitive advantages for a firm. The management of a supply chain encompasses these two elements, which together emphasize the importance of getting goods/services to customers at the right time, in the right place, under the right conditions, in the right quantities, and at the lowest possible costs. Porter (1985) emphasizes that, differentiation, one type of competitive advantage for a firm, is closely linked to the customer values of the product/service that can be delivered. Low cost, another type of competitive advantage, is reflected in the costs of the product/service to the customers. Christopher (1998) adds that a firm would achieve a competitive advantage by striving for excellence in both service and cost leadership. To this end, making proper performance measurement of a supply chain is necessary as it cultivates understanding between member firms in the supply chain for performance improvement (Dreyer, 2000; Fawcett and Cooper, 1998). Traditionally, the focus of performance measurement has been on process operations within the organizational boundaries of a firm (Short and Venkatraman, 1992). In the context of SCM, performance measurement involves not only the internal processes, but also requires an understanding of the performance expectation of other member firms in the supply chain, backward from the suppliers and forward to the customers (Normann and Ramırez, 1993). Coordination between the various parties in the supply chain is key to its effective implementation (Frohlich and Westbrook, 2001). As SCM focuses on process management beyond organizational boundaries, there is a need to measure performance for the effective management of a supply chain. Harrington (1991, p. 164) states that ‘If you cannot measure it, you cannot control it. If you cannot control it, you cannot manage it. If you cannot manage it, you cannot improve it’. In fact, the lack of relevant performance measures has been recognized as one of the major problems in process management (Davenport et al., 1996) and the management of a supply chain (Dreyer, 2000). Because of the different views on what should constitute supply chain performance (SCP), many firms have found it difficult to practice SCM (Beamon, 1999). A major contributing factor to this problem is that, with multiple parties having different interests, it is difficult for firms to effectively evaluate the performance of their activities on a supply chain-wide basis (Cooper et al., 1997). Consequently, firms in different parts of the supply chain tend to work to improve performance in those areas within their interest. To overcome this problem, they need a comprehensive overview of their supply chain activities and full appreciation of the impact of their performance on other member firms in the supply chain. The objective of this study is to investigate the construct of, and develop a measurement instrument for, SCP with a focus on the intermediary component, i.e., transport logistics, in a supply chain process. A measurement instrument is a collection of measuring items applied collectively to reveal a theoretical construct, e.g. SCP in transport logistics, which cannot be assessed directly (DeVellis, 1991). Given the ambiguity in the literature and the lack of empirically validated measurement instruments for SCP, this research objective is well justified with the aim to extend SCM research to the transport logistics context. We identify the components of SCP in transport logistics, develop the measurement items and instrument, evaluate their validity using empirical data, discuss the implications of the SCP construct, and provide suggestions for using the validated measures in substantive research and practice in transport logistics. 440 K.H. Lai et al. / Transportation Research Part E38 (2002) 439–456
441K.H.Lai etal./TransportationResearchPartE38 (2002)439-4562.Conceptual backgroundSCM is concerned with managing the upstream and downstream relationships with suppliersand customers to deliver superior customer value at the least cost to the chain as a whole(Christopher, 1998).Implementation of SCM requires that the internal perspective of perfor-mance measures be expanded to include both“interfunctional"and“partnership"perspectivesand avoid inward-looking and self-focused attitudes in the management approach (Holmberg,2000).This isto beachieved by closely integrating the internal functions within afirm and ef-fectively linking them with the external operations of member firms in the chain.To this end, anappropriateperformancemeasurement is conduciveto successful sCMimplementation(Lee andBillington, 1992).Mentzer and Konrad (1991)define performance measurement as effectiveness and efficiency inaccomplishing a given task in relation to how well a goal is met. In the logistics and supply chaincontext, effectiveness is concerned with the extent to which goals are accomplished and they mayincludelead-time, stockoutprobability,andfill rate.Efficiencymeasures how well theresourcesare utilized, for which themeasures may include inventory costs and operating costs. While manyfirms recognize both aspects of performance, they fail to understand them from a perspective of abalanced frameworkforperformance measurement (Brewerand Speh,2000).This could bedisruptive for performance management in a supply chain.For instance, one firmmay concen-trateon operationalefficiency,whiletheothersaremoreoncernedwithserviceeffectivenessinthe supply chain.The differences in the views of SCP would lead to inconsistency in the perfor-mancemeasures used across memberfirms in a supplychain andconsequently suboptimizesupplychain-wide performance (Bechtel and Jayaram, 1997; Caplice and Sheffi, 1995; Gunasekaranet al., 2001).Traditional performance measures such as profitability are less relevant for measuring SCPbecause they tend to have an “individual focus"and fail to consider chain-wide areas for per-formance improvement.Bechtel and Jayaram (1997)advocate the use of integratedmeasures, inaddition to non-integrated measures, that motivate firms to consider chain-wide performance,rather than their own individual performance measures.An exampleof an integrated measure iscash-to-cash cycle that spans functional and organizational boundaries to show all member firmshowthechainisperforming,andfostersincentivesforfirmstoworkwithothersinthechain.Incontrast, non-integrated measures only provide insights into potential problems within individualfirms in a supply chain.Otherthan integrated performancemeasures,there are conceptual frameworks on SCP.New(1996)presents a taxonomy for the classification of supply chain improvement.van Hoek (1998)proposes a framework at the firm's level of integration in the supply chain and the strategyadopted. Beamon (1999)develops a performance evaluation framework for manufacturingsupply chains, where resources, output, and flexibility are considered necessary components forSCP.Shah and Singh (2001)provide a framework for benchmarking internal SCP.Gunasek-aran et al. (2001) develop a conceptual model for SCP at three management levels. Even thoughthereexist a varietyof frameworks for SCPmeasurement,many companies still managetheirsupply chain in a way different from what their member firms desire. The main reason is thatthey lack agreement of goals and performance measures in their supply chain activities (Tanet al., 1999)
2. Conceptual background SCM is concerned with managing the upstream and downstream relationships with suppliers and customers to deliver superior customer value at the least cost to the chain as a whole (Christopher, 1998). Implementation of SCM requires that the internal perspective of performance measures be expanded to include both ‘‘interfunctional’’ and ‘‘partnership’’ perspectives and avoid inward-looking and self-focused attitudes in the management approach (Holmberg, 2000). This is to be achieved by closely integrating the internal functions within a firm and effectively linking them with the external operations of member firms in the chain. To this end, an appropriate performance measurement is conducive to successful SCM implementation (Lee and Billington, 1992). Mentzer and Konrad (1991) define performance measurement as effectiveness and efficiency in accomplishing a given task in relation to how well a goal is met. In the logistics and supply chain context, effectiveness is concerned with the extent to which goals are accomplished and they may include lead-time, stockout probability, and fill rate. Efficiency measures how well the resources are utilized, for which the measures may include inventory costs and operating costs. While many firms recognize both aspects of performance, they fail to understand them from a perspective of a balanced framework for performance measurement (Brewer and Speh, 2000). This could be disruptive for performance management in a supply chain. For instance, one firm may concentrate on operational efficiency, while the others are more concerned with service effectiveness in the supply chain. The differences in the views of SCP would lead to inconsistency in the performance measures used across member firms in a supply chain and consequently suboptimize supply chain-wide performance (Bechtel and Jayaram, 1997; Caplice and Sheffi, 1995; Gunasekaran et al., 2001). Traditional performance measures such as profitability are less relevant for measuring SCP because they tend to have an ‘‘individual focus’’ and fail to consider chain-wide areas for performance improvement. Bechtel and Jayaram (1997) advocate the use of integrated measures, in addition to non-integrated measures, that motivate firms to consider chain-wide performance, rather than their own individual performance measures. An example of an integrated measure is cash-to-cash cycle that spans functional and organizational boundaries to show all member firms how the chain is performing, and fosters incentives for firms to work with others in the chain. In contrast, non-integrated measures only provide insights into potential problems within individual firms in a supply chain. Other than integrated performance measures, there are conceptual frameworks on SCP. New (1996) presents a taxonomy for the classification of supply chain improvement. van Hoek (1998) proposes a framework at the firm’s level of integration in the supply chain and the strategy adopted. Beamon (1999) develops a performance evaluation framework for manufacturing supply chains, where resources, output, and flexibility are considered necessary components for SCP. Shah and Singh (2001) provide a framework for benchmarking internal SCP. Gunasekaran et al. (2001) develop a conceptual model for SCP at three management levels. Even though there exist a variety of frameworks for SCP measurement, many companies still manage their supply chain in a way different from what their member firms desire. The main reason is that they lack agreement of goals and performance measures in their supply chain activities (Tan et al., 1999). K.H. Lai et al. / Transportation Research Part E38 (2002) 439–456 441
442K.H.Laietal./TransportationResearchPartE38(2002)439-456Table 1ScORperformance measures fora supplychainSupply chain processMeasurement criteriaPerformanceindicatorsCustomerfacingSupply chain reliabilityDelivery performanceOrderfulfillmentperformancePerfect order fulfillmentFlexibility and ResponsivenessSupply chain response timeProduction flexibilityInternal facingCostsTotal logistics management costsValue added productivityReturn processing costAssetsCash-to-cash cycle timeInventory days of supplyAsset turnsAmong the extant sCP conceptualizations, the supply chain operations reference model(SCOR) developed by the Supply Chain Council (cf. Stewart, 1995)provides a useful frameworkthat considers the performance requirements of member firms in a supply chain. The SCORmodel views activities in the supply chain as a series of interlocking interorganizational processeswith each individual organization comprising four components: plan, source, make, and deliver.Each of these components is considered a critical intraorganizational process in the supply chainwithfourmeasurement criteria:(1)supply chain reliability,(2)responsiveness/flexibility,(3)costs,and (4) assets.The first two criteria deal with effectiveness-related (customer-facing)performancemeasures, while the other two are efficiency-related (internal-facing) performance measures of afirm. Customer-facing measures are concerned with how well a supply chain delivers products/services to customers, e.g.delivery performance.Internal-facing measures are concerned with theefficiency with which a supply chain operates, e.g. cash-to-cash cycle time (cf. Geary, 2001).In line with MentzerandKonrad (1991),the SCOR model provides an indication as to howeffective a firm uses resources in creating customer value. It considers the performance expecta-tions of member firms on both input and output sides of supply chain activities.The measurementcriteriaandindicatorsofperformancemeasurementinSCORacrosssupplychainmembers(cf.Stephens,2000), shown in Table l,providea useful framework for developing a construct and thecorrespondinginstrumentforSCPmeasurementinthetransportlogisticscontext.3. SCP in transport logisticsTransport logistics in a supply chain is usually an intermediary that facilitates the physical flowsof goods from a point of origin, i.e., shipper, to a point of destination, i.e., consignee.Firms intransport logistics perform the physical distribution function to move goods from one place toanother (Coyle et al., 1996) and the business process spans organizational boundaries, encom-passing shippers and consignees.Under this conception, SCP in transport logistics involves shippers on the input side andconsignees on the output side. The goal of a transport logistics service provider is to satisfy the
Among the extant SCP conceptualizations, the supply chain operations reference model (SCOR) developed by the Supply Chain Council (cf. Stewart, 1995) provides a useful framework that considers the performance requirements of member firms in a supply chain. The SCOR model views activities in the supply chain as a series of interlocking interorganizational processes with each individual organization comprising four components: plan, source, make, and deliver. Each of these components is considered a critical intraorganizational process in the supply chain with four measurement criteria: (1) supply chain reliability, (2) responsiveness/flexibility, (3) costs, and (4) assets. The first two criteria deal with effectiveness-related (customer-facing) performance measures, while the other two are efficiency-related (internal-facing) performance measures of a firm. Customer-facing measures are concerned with how well a supply chain delivers products/ services to customers, e.g. delivery performance. Internal-facing measures are concerned with the efficiency with which a supply chain operates, e.g. cash-to-cash cycle time (cf. Geary, 2001). In line with Mentzer and Konrad (1991), the SCORmodel provides an indication as to how effective a firm uses resources in creating customer value. It considers the performance expectations of member firms on both input and output sides of supply chain activities. The measurement criteria and indicators of performance measurement in SCORacross supply chain members (cf. Stephens, 2000), shown in Table 1, provide a useful framework for developing a construct and the corresponding instrument for SCP measurement in the transport logistics context. 3. SCP in transport logistics Transport logistics in a supply chain is usually an intermediary that facilitates the physical flows of goods from a point of origin, i.e., shipper, to a point of destination, i.e., consignee. Firms in transport logistics perform the physical distribution function to move goods from one place to another (Coyle et al., 1996) and the business process spans organizational boundaries, encompassing shippers and consignees. Under this conception, SCP in transport logistics involves shippers on the input side and consignees on the output side. The goal of a transport logistics service provider is to satisfy the Table 1 SCORperformance measures for a supply chain Supply chain process Measurement criteria Performance indicators Customer facing Supply chain reliability Delivery performance Order fulfillment performance Perfect order fulfillment Flexibility and Responsiveness Supply chain response time Production flexibility Internal facing Costs Total logistics management costs Value added productivity Return processing cost Assets Cash-to-cash cycle time Inventory days of supply Asset turns 442 K.H. Lai et al. / Transportation Research Part E38 (2002) 439–456
443K.H.Lai etal./Transportation ResearchPartE38 (2002)439-456customers (both upstream and downstream) in the chain with greater effectiveness and efficiencythan the competitors. The measurement of sCP in transport logistics needs to incorporate theseperformance aspects to be successful. For example, cost efficiency in providing the services mightbe an important performance measure for a transport logistics service provider. However, thismight not be desired by shippers and consignees. They would instead demand high quality andlow-pricedelivery of shipments conforming totheirrequirements.Anotherexampleis that de-laying shipments until carriage infull truck loads is possible may reduce the costs for organizingthedeliveryandimproveefficiencymeasuresforthetransportlogistics serviceprovider.However,this would lead to a reduction in the service effectiveness provided to shippers and consigneesNeither performance measures alone, effectiveness and eficiency,can fully reflect sCP in trans-portlogistics.In this regard, sCP in transport logistics should encompass not only operations eficiencyparameters, but also measures of service effectiveness (Kleinsorge et al.,1991) to meet the goals ofall parties,i.e., shipper, service provider and consignee. It must not be centered only on individualfunctional areas, but rather on the different parties involved in the transport logistics processesandtheoverallSCP(Cavinato.1992:Lee,2000)To this end, the SCORmodel in Table1 provides a useful framework.It represents a systematicapproach tomeasuringperformancewith inputs from,and outputs to,member firms in the supplychain and considers performanceassessment ona supply chain-widebasis,not just on that of anindividual component, e.g.providers of transport logistics services, in the chain. This is an im-portant point because it not only identifies both the effectiveness and efficiency aspects of per-formance, but also recognizes that there can be internal as well as customer-related reasons forperformance measurement. Based on this, three dimensions of SCP in transport logistics areidentified.Theseare: Service effectiveness for shippers (SES);.Operations efficiencyfortransport logistics serviceproviders (OE);.Serviceeffectivenessforconsignees (SEC).SES and SEC measure how well the activities are performed to meet the requirements ofshippers and consignees,respectively.OErefersto the efficiency of a transportlogisticsserviceprovider in the use of resources to perform its service activities. These three dimensions of SCP intransport logistics are congruent with the critical components for supply chain success postulatedin the SCOR model. In this study, the three-factor structure of the SCP construct is tested in afirst-order model, where SES, OE and SEC correlate among themselves in measuring the sameconstruct,i.e.,SCPintransportlogistics,andinasecond-ordermodel,wheretheSCPconstructistreated as a higher order model governing the covariance of the three dimensions of SES, OE andSEC.4.MethodologyFollowing Churchill's (1979)paradigmfor construct measurement, we first define the domainof a SCP construct in transport logistics, then operationalize the construct by developing a
customers (both upstream and downstream) in the chain with greater effectiveness and efficiency than the competitors. The measurement of SCP in transport logistics needs to incorporate these performance aspects to be successful. For example, cost efficiency in providing the services might be an important performance measure for a transport logistics service provider. However, this might not be desired by shippers and consignees. They would instead demand high quality and low-price delivery of shipments conforming to their requirements. Another example is that delaying shipments until carriage in full truck loads is possible may reduce the costs for organizing the delivery and improve efficiency measures for the transport logistics service provider. However, this would lead to a reduction in the service effectiveness provided to shippers and consignees. Neither performance measures alone, effectiveness and efficiency, can fully reflect SCP in transport logistics. In this regard, SCP in transport logistics should encompass not only operations efficiency parameters, but also measures of service effectiveness (Kleinsorge et al., 1991) to meet the goals of all parties, i.e., shipper, service provider and consignee. It must not be centered only on individual functional areas, but rather on the different parties involved in the transport logistics processes and the overall SCP (Cavinato, 1992; Lee, 2000). To this end, the SCORmodel in Table 1 provides a useful framework. It represents a systematic approach to measuring performance with inputs from, and outputs to, member firms in the supply chain and considers performance assessment on a supply chain-wide basis, not just on that of an individual component, e.g. providers of transport logistics services, in the chain. This is an important point because it not only identifies both the effectiveness and efficiency aspects of performance, but also recognizes that there can be internal as well as customer-related reasons for performance measurement. Based on this, three dimensions of SCP in transport logistics are identified. These are • Service effectiveness for shippers (SES); • Operations efficiency for transport logistics service providers (OE); • Service effectiveness for consignees (SEC). SES and SEC measure how well the activities are performed to meet the requirements of shippers and consignees, respectively. OE refers to the efficiency of a transport logistics service provider in the use of resources to perform its service activities. These three dimensions of SCP in transport logistics are congruent with the critical components for supply chain success postulated in the SCORmodel. In this study, the three-factor structure of the SCP construct is tested in a first-order model, where SES, OE and SEC correlate among themselves in measuring the same construct, i.e., SCP in transport logistics, and in a second-order model, where the SCP construct is treated as a higher order model governing the covariance of the three dimensions of SES, OE and SEC. 4. Methodology Following Churchill’s (1979) paradigm for construct measurement, we first define the domain of a SCP construct in transport logistics, then operationalize the construct by developing a K.H. Lai et al. / Transportation Research Part E38 (2002) 439–456 443