SUBROUTINE ZONE_CLEAR(zone)
      
#include "dyna.inc"
#include "zone.inc"
      
      RECORD /Zone_Data/   zone

      INTEGER izn,i,j
      
      zone.index     = 0
      zone.number    = 0
      zone.destnode  = 0
      zone.destindex = 0
      DO izn = 1,NU_ZN
         DO i = 0,1
            zone.tto(izn,i) = 0.D0
            DO j = 0,1
               zone.nreach(izn,i,j) = 0
               zone.ngen(i,j,izn)   = 0
               ENDDO
            ENDDO
         DO i = 1,MAX_DEMAND_INTERVALS
            zone.demand(izn,i) = 0.D0
            zone.cumdem(izn,i) = 0.D0
            ENDDO
         ENDDO
      DO i = 1,MAX_DEMAND_INTERVALS
         zone.totdem(i) = 0.D0
         ENDDO
      zone.totlmz  = 0.D0
      zone.expgenz = 0.D0
      zone.numgenlink = 0
      DO i = 1,MAX_GENERATION_LINKS
         zone.genlink(i) = 0
         ENDDO
      DO i = 1,K_EQ
         zone.famsplit(i) = 0.D0
         ENDDO
      DO i = 1,3   ! HARDCODED 3 types
         zone.ifamz(i) = 0
         ENDDO
      RETURN
      END
            
      INTEGER FUNCTION ZONE_READ(unit,zone)
      
#include "dyna.inc"
#include "zone.inc"
      
      INTEGER unit
      RECORD /Zone_Data/ zone

      INTEGER j
      
      CALL ZONE_CLEAR(zone)
      CALL FND(unit)

      READ(unit,14,END=96600)
     +     zone.number,zone.destnode
     +     ,(zone.famsplit(j),zone.ifamz(j),j=1,3)
   14 FORMAT(2I5,3(F5.2,I2))
      
      ZONE_READ = 0
      RETURN

C   - Zone not read
96600 ZONE_READ = 1
      RETURN
      END
      
      
      INTEGER FUNCTION ADD_ZONE(sim,act,zone)
      
#include "dyna.inc"
#include "sim.inc"
#include "activity.inc"
      
      RECORD /Sim_Data/     sim
      RECORD /Activity/     act
      RECORD /Zone_Data/    zone
      
      INTEGER znum
      INTEGER ico
      
      znum = act.nzones + 1
      
C   - CHECK IF GEOMETRY EXCEEDS PROGRAM PARAMETERS
      IF (znum.GT.NU_ZN) THEN
         WRITE(ostr,690) znum,NU_ZN
  690    FORMAT(/'ERROR: Number of zones ['I4
     +        ,'] greater than array parameter NU_ZN ['I4']')
         CALL DYNA_ERROR(ostr
     +        ,DYNA_FATAL_ERROR
     +        ,DYNA_OUT_OF_MEMORY
     +        ,DYNA_TOO_MANY_ZONES)
         ENDIF
      
      IF (zone.number.LE.0.OR.zone.number.GT.MAX_ZN_NU) THEN
         WRITE(ostr,650) zone.number,CHAR(0)
  650    FORMAT('Invalid zone number ['I5']'A)
         CALL DYNA_ERROR(ostr
     +        ,DYNA_FATAL_ERROR
     +        ,DYNA_INPUT_ERROR
     +        ,DYNA_INVALID_ZONE_NUMBER)
         ENDIF

      act.zonelist(zone.number) = znum
      
      zone.totlmz = 0      !INITIALIZE THE TOTAL LANE MILES IN EACH ZONE
      
      IF(zone.destnode.GT.0) THEN
         ico=act.ndests+1
         act.destlist(ico)=zone.destnode ! See below
         act.dest2zone(ico)=znum   ! redundant but more useful
         zone.destindex=ico
         act.ndests = act.ndests + 1
        ELSE
         zone.destindex=0
         ENDIF
      
      act.zone(znum) = zone
      act.nzones = act.nzones + 1
     
      ADD_ZONE = 0
      
      RETURN
      END