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manufacturers regarding physical dimensions of the equipment in which he is interested. Size and weight information which is necessary for determining vehicle length, using the procedure pre- sented in Appendix I, can be obtained from the "Summary of Size and Weight Limits" chart. The infor- mation necessary to use the procedure can be obtained from that half of the chart which names the states and has them grouped into regions. It should be noted that in the other half of the "Summary of Size and Weight Limits" chart is a table called "Tables for Allowable Loads (in 1000 Ibs.)." That is called a bridge table. I t represents a method states use to assign weights and vehicle axle spacings in a manner which each state feels will place the least stress on bridges located in that parti- cular state. This table says, in effect, that to be able to haul X number of pounds on a vehicle you need Y number of feet between the axles of that vehicle. In some states the table applies only to placement of the first and last axle of a vehicle, and in other states to the placement of all axles. It is this table to which a truck operator must refer when he specifies the distance between axles of the vehicle he will purchase. To deter- mine accurately the exact wheelbase of tractor and semi- trailer to be used in a state which uses a bridge table, one must know the weight to be hauled, how much is to be loaded on each axle, and equipment parameters which physically limit the placement of axles. Since architects generally do not have all that information available to them, particularly the information regarding physical parameters set by equipment, it would be very difficult for them, through use of bridge table data, to determine tractor and semitrailer wheelbase dimensions for the vehicle requiring most maneuvering space in any particu- lar state. The procedure presented in Appendix I assumes architects do not have available to them the information which would be necessary fo! using the bridge table to determine tractor and semitrailer wheelbase dimensions for that vehicle requiring maximum maneuvering space in any particular state. Since the tractor-semitrailer is usually the vehicle which will require most space for maneuvering, the procedure for determining vehicle size presented in Appendix I is basically for determining the tractor-semitrailer which will off track most and which, hence, will require the most space to maneuver. For a tractor-semitrailer combination, the factor con. tributing most to off track is the semitrailer wheelbase. The factor next in importance is tractor wheelbase (wb). Consequently, to obtain the tractor-semitrailer combina- tion which gives the most off track in a particular state, a se m i trailer incorporating the maximum semitrailer wheelbase possible in that state must be coupled with a tractor of maximum wheelbase compatible with that semitrailer. The procedure presented in Appendix I is for determining that combination of tractor and semitrailer. I t is possible that the tractor-semitrailer developed, using the procedure presented in Appendix I, will not be one which is used most generally in a particular state. The vehicle developed will, however, be one which might be found in that state and would be the tractor. semitrailer which, in that state, would require the most space to maneuver. 4