Many people believe that having a systematic travel approval system increases control. For example: Software is used for the travelers to submit a request to travel; the request is routed to the manager, cost center manager, etc. Another: Your online booking tool requires formal approval before the reservation is queued for ticketing.
While above examples do monitor the approval process, they are not the best practice way for many reasons. There are many instances of missed ticketing, as some airfares must be ticketed at time of booking. At one company, when I asked how often the travel approval requests get denied, the answer was, "Never." At another company, all International travel approval had to be routed to the CFO, after it was routed to the manager, cost center manager and finance analyst. Imagine someone (your CFO) whose signing authority exceeded $millions approving an expenditure for $5,000. What a waste of his time!
Instead of adding more processes that drive everyone nuts, let me explain how you can add control by subtracting processes.
Subtract systematic approval systems and add control by requiring travelers to obtain some type of approval prior to planning the trips. Increase control by switching to "passive approval." When the reservation is being arranged, the online/offline messaging to the traveler is, "You did already obtain approval, right?"
Subtract the need for documentation (e.g. print out of the email approval, etc.).
Work to subtract processing time for arranging trips and submitting expense reports.
Subtract use of individual credit card (personal responsibility) for airfares and add control by implementing a central billing card or company-paid T&E card. This allows for better forecasting of expenses, including better accrual processes, and also minimizes fraud associated with the use of personal credit card.
Add control by implementing an end-to-end trip submission to expense reimbursement mechanism, which subtracts processing time of expense reports and headcounts, subtracting the need for 100 percent expense audit and only reviewing exceptions.
When I surveyed the travelers and arrangers at one company and asked, "Do you have any suggestion/feedback?," here was one answer that really resonated with me: "I want the freedom to make informed decisions (e.g. whether to take a connecting flight or not, whether an expensive meal is appropriate for a specific location) with the responsibility to spend (company)'s money as if it were my own (look for bargains, use suppliers I trust, plan and execute responsibly)." BINGO!
My belief, which is supported by numerous studies and research, is that if you provide your travelers/arrangers the right infrastructure (booking methods, information availability, policy, ease of expense submission to reimbursement, best customer service from every support staff of travel management, including you, the travel program manager), most (perhaps 90%+?) will try to do the right thing. You of course "trust and verify" from time to time by conducting audits to identify any control "soft spots," but you will find that only a minority of your traveler/arranger population requires true attention/corrective action.