If you are looking for temporary wind loads for construction, you may be able to reduce the velocity if AASHTO permits. The only document I know of that treats construction loads is the ASCE 37-02. You may end up designing for, say, 10-year wind instead of 50-year wind or whatever recurrence interval AASHTO uses. Of course if the code does not allow you to reduce wind loads for construction purposes you're stuck. If you can use 70mph instead of 100mph, either way that will help.