The idea is to have lockers fitted into trains and buses. The lockers can then be hired, a parcel can be placed in the locker and the customer will receive a unique code to unlock the locker that they can share with the recipient.
Simply to provide an alternative delivery system, especially for intra-city deliveries that do not require a lot of paperwork, packaging or issues with delivery service providers.
Trains and buses keep a regular schedule and have set stops throughout the day. You would be able to "buy a code" to unlock a certain box, deposit your package, and share the code and box ID with the intended recipient who will also be notified at what times the train/bus will be at a station near him/her.
This could be especially convenient for parcels that are sent from one person to another within the same city. Sometimes people simply don't have the time to deliver a package themselves but also don't want to go through all the red tape involved in sending a parcel via a courier company.
In order to prevent people from using the lockers as storage and to promote the speedy collection, the lockers can charge people according to how long the recipient takes to pick up their items. The "meter" would essentially start when the box is opened for the first time, and stop when it is opened again.
The biggest problem I see with this idea is that it might delay trains/buses as they usually don't stop for very long but might have to wait for people who are only dropping or collecting a package to get on and off before they can depart.
This could potentially be solved by having the lockers be removed at their destined stations, but this would still take up time and require staff specifically designated to do this job.
Another potential issue is that this seems like an excellent way to distribute illegal narcotics. This could possibly be helped by making the lockers transparent, it won't eradicate the problem, but would help.
That said, in communities where many people make use of public transport anyway, this could still be a great system, as people could then simply collect or deposit the parcel when they are on their way to and from work/town.