Given is a circular bus route with $n\geqslant2$ bus stops. The route can be frequented in both directions. The way between two stops is called [i]section[/i] and one of the bus stops is called [i]Zürich[/i]. A bus shall start at Zürich, pass through all the bus stops [b]at least once[/b] and drive along exactly $n+2$ sections before it returns to Zürich in the end. Assuming that the bus can chance directions at each bus stop, how many possible routes are there?

EDIT: Sorry, there was a mistake...corrected now, thanks mavropnevma!  :oops:
To solve this problem, we need to determine the number of possible routes a bus can take on a circular route with \( n \geq 2 \) bus stops, starting and ending at Zürich, passing through each bus stop exactly once, and traveling along exactly \( n+2 \) sections.

1. **Understanding the Problem:**
   - The bus starts at Zürich.
   - It must pass through each bus stop exactly once.
   - It must travel along exactly \( n+2 \) sections.
   - The bus can change directions at each bus stop.

2. **Key Observations:**
   - Since the bus must travel \( n+2 \) sections and there are \( n \) bus stops, the bus will pass through Zürich twice (once at the start and once at the end).
   - The bus will travel \( n \) sections to visit each bus stop exactly once.
   - The additional 2 sections imply that the bus will pass through Zürich once more during its journey.

3. **Route Construction:**
   - Let's denote the bus stops as \( Z, A_1, A_2, \ldots, A_{n-1} \), where \( Z \) is Zürich.
   - The bus can travel in either direction (clockwise or counterclockwise) and can change directions at any bus stop.

4. **Counting the Routes:**
   - The bus can start in either direction from Zürich, giving us 2 initial choices.
   - After starting, the bus must travel \( n \) sections to visit each bus stop exactly once.
   - The bus must then travel 2 additional sections to return to Zürich, which means it must pass through Zürich once more during its journey.

5. **Detailed Calculation:**
   - For each of the \( n \) bus stops, the bus can either continue in the same direction or change direction.
   - This gives us \( 2^n \) possible ways to travel through the \( n \) bus stops.
   - Since the bus can start in either direction, we multiply by 2.

Therefore, the total number of possible routes is:
\[ 2 \times 2^n = 2^{n+1} \]

The final answer is \( \boxed{ 2^{n+1} } \).