Design a toll system for highways.
Amazon- Angela Blue
Clarify the Scope:
To clarify, you mean a toll system on highways that collects tolls from vehicles using highways via different modes (scanners, cash collection, RFID systems, etc.)
Are we focusing on the entire toll system experience (booth and other tech – eg. any kind of app/web to pay or track, etc.) or only the toll system?
Interviewer(I) – You say…its yours to choose
A – I would say for the scope of discussion, let’s limit it to the collection of tolls on highways. Also lets limit it to booths only and not auto-detections of vehicles via GPS or video camera system points.
Are we trying to solve this for a particular region or globally?
A – You say…
For the moment, let’s discuss it for USA
WHY?
First of all, I would like to know why do we need a toll system designed? Is it because of a flaw noticed in current toll systems or anything else is identified that is deemed as a problem?
Problem: The current toll system is not accurate and is too slow.
Ok. So when we speak about being accurate and being too slow, could I assume that it doesn’t charge correctly (under or above or nothing) and the automated scanning requires / collection booths to reduce speed about 20mph or 0mph (cash payments or slow readings by scanners) causing delays and traffics at highways.
NSM / Goal: The goal for this toll system should be to be more accurate and faster. The North Star Metric that I could think to tie to this goal will be # Avg Vehicles passing a toll booth per minute with 100% accuracy. (No faults recorded or complaints received from vehicle owner as well as the toll system)
WHO?
Let’s try to define few user groups for whom the defined problem is actually a problem, estimate their market size and user pain via T-shirt sizing
| User Groups | Market Size | User Pain (Compared to Goal) |
| Office Workers / Executives (9 to 5 pm jobs) | XL | L |
| Travelers | M | M |
| Leisure / Entertainment Seekers | M | S |
| Transport Drivers (Trucks) | L | M |
| Emergency / Urgent Travels | S | L |
For this discussion, we will be focusing on office workers / executives user group for whom the market size is relevant and large, and also the problem (toll system being slow) impacts the most as they have to reach to their workplace on time and wish to return home on time as well without having any delays on highways
Next up, we try to figure out the pain areas or pain points for the selected user group.
| User Pain Areas | Impact to User Group |
| Delay at toll booths because of speed reduction | L |
| Inaccurate and delayed scanning of RFID tags/express pass | S |
| Mix Lanes for Cash / Card / Express payment and Only Pass modes causing traffic and delays | M |
| Narrow roads at toll booths through partitions | M |
| Slow collections of tolls in case of cash or cards | L |
WHAT?
Next, for each of the most impacted user pain areas, we will try to come up with features/solutions.
I know the tech used behind current toll collection systems for express lanes via EZ-Pass or similar systems, they use passive RFID tags which needs to come in a short range of electromagnetic frequency to emit the message or get read. Its a slow process which causes major bottlenecks at the toll booths on highways
| User Pain Areas | Features / Solutions |
| Delay at toll booths because of speed reduction |
|
| Mix Lanes for Cash / Card / Express payment and Only Pass modes causing traffic and delays |
|
| Narrow roads at toll booths through partitions |
|
| Slow collections of tolls in case of cash or cards |
|
Now map them to development effort and impact to overall goal (NSM) to come up with prioritization of the development.
| Features/Solutions | Development Effort | Impact to Overall Goal(NSM) | Prioritization |
| Install ultra high quality cameras to capture images of cars from front and rear at speeds upto 100mph | M | L | P1 |
| Using advanced AI/ML techniques, a car or vehicles could be tagged and number plate determined from front and rear pics to map entry/exit | L | L | P0 |
| Create a system to deduct the toll from the user’s account associated with that vehicle. | M | L | P1 |
| Users can get a monthly invoice based on their usage which could be paid out online or through banks/cheque | S | M | P2 |
| No toll booths should be made in way of highways or removed if made previously | L | L | P0 |
Finally, I will summarize the entire toll system.
– To solve the problem of slowness and accuracy in current toll systems for the executives and workers driving on highways at peak times, I recommend building a toll system with no toll booths, an AI/ML-based automatic vehicle recognition system at speeds up to 100mph and auto-debit tolls or initiate postpaid collection for tolls.