Table 2 Definition of the Dummy Variables Included in the Estimated Demand Equation

Table 2
Definition of the Dummy Variables Included in the Estimated Demand Equation

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Dummy variables Period Comment Expected sign
Z1-Z4 1994 - 1998 They reflect the negative impact on traffic on the 4 A(2) motorway sections, derived from capacity and quality improvements on the alternative free road.
Z5-Z7 1992 They account for the positive impact on the 3 A(4) motorway sections, derived from the Seville World Exhibition in 1992. +
Z8-Z11 1995 - 1998 They reflect the negative impact on traffic on 4 A(7) motorway sections as a consequence of the extension of an alternative tollway.
Z12, Z14, and Z16 1993 - 1998 They reflect the negative impact on traffic on 3 A(7) motorway sections, derived from the opening of an alternative free motorway.
Z13, Z15, and Z17-Z24 1990 - 1998 They account for the positive impact on traffic on 10 A(7) motorway sections, due to the extension of this motorway. +
Z25 1996 - 1998 It reflects improvements in the free alternative motorway network for the first of the A(19) motorway sections.
Z26, Z27, and Z28 1994 - 1998 They account for the positive impact on traffic on the 3 A(66) sections as a consequence of the improvement and extension of the motorway. +

Notes: In Spain, the motorways (autopistas) are identified by the letter "A" followed by a number in parentheses.

These variables take the value 1 in the reported period; otherwise they are 0.