The Commercial Port is one of the best features in the game: a good source of city dollars and an interesting way to collaborate with friends. I managed to complete the port and get the bonus Safe with over 4 days left on the time limit. Here is how I did it.
The first thing to realize is that almost everything you need for this quest can be made in advance and it is critical that you do so. The time limit on the quest is 10 days. You will most likely spend much more time than that BEFORE starting the quest to gather all the needed materials and facilities.
Once you have started the quest proper (and the 10 day timer), only 2 tasks will take a long time: Task 3 Step 2 (gathering energy for workers) and Task 4 Step 2 (collecting steel details). You can buy your way out of Task 3 (I spent 24 city dollars to replenish energy a few times) but collecting steel details really requires the time to do. Steel details drop VERY infrequently, so you will need to spend several days to a week clicking on all your donut cafés every 20 minutes. It's a tough grind but it's what you have to do if you want that Safe and the nano generator blueprint. I used a timer app on my ipad and a weekend of movie marathons to help.
If you have a day job, you should plan vacation/weekend time at the Day 3 mark in the quest. Tasks 1-3 takes 2 or 3 days, so plan your schedule to have a maximum amount of free time to play the game in the 3rd and 4th days, returning every 20 minutes to find steel details.
Be careful not to accidentally sell goods that you collect for tasks (especially the milk shakes). The user interface allows you to do this easily and it can hopelessly delay you, especially if you can't spend city dollars to cover a mistake.
Here are my recommended steps for completing the Commercial Port quest. The order is not strict but I mention the stuff that takes longer earlier in the list. Also the steps listed before starting the quest must be done before actually starting the commercial port quest (and thus the timer).
0. Research all the tasks of the quest to familiarize yourself with what is coming (some good wikis out there). Read this document all the way to the end.
1. Upgrade your warehouse to level 5. The extra space in convenient anyway so might as well do this first.
2. Build 2 colleges. You need this to create drivers for the terminal and workers for the quest.
3. Expand Terminal(s) until you have 4 taxies and a few buses. You need the taxis for the Steel Bolt and buses to get bananas for the milkshakes. Bananas only cost 1 dollar each, so, if you are ok with spending $10, you can forget about the buses.
4. Start training 10 workers at the colleges. Complete before starting the quest.
5. Collect 5 pumps and 8 hammers from friends. This can take quite a while if you don't have a lot of friends. You can get pumps from the terminal as well.
6. Build 18 Donut Cafés. Yes, 18, not just the 10 that the Task requires. You need all the help you can get with the Steel Details.
7. Build 5 News Stands.
8. Make 10 Milk Shakes. Bananas come from terminal buses.
9. Collect $100,000 in cash and keep it in reserve until Task 4 where you will spend it.
10. Accumulate $15000 worth of goods in your warehouse (not counting the Milk Shakes).
11. Start the Commercial Port quest. You now have 10 days to complete it to get the Safe.
12. Complete Task 1. Build 10 wood planks while doing so.
13. Complete Tasks 2 and 3. Steel bolt comes from Taxis at the Terminal.
14. You should be 2 or 3 days in the quest at this point. Start and complete task 4 and 5. Steel details come from donut cafés which drop every 20 minutes. Good Luck!
15. When the quest is complete click on the port to get the bonus Safe.
Taken from a forum post.