Sure, I can help you generate a test case generator for the given problem "A Long Ride on a Railway". Here's a Python function that can generate random test cases for this problem:

```python
import random

def tcgen():
    # Number of stations (1 <= ns <= 10)
    ns = random.randint(1, 10)
    
    # Number of routes (1 <= nl <= 20)
    nl = random.randint(1, 20)
    
    routes = []
    existing_routes = set()
    
    for _ in range(nl):
        while True:
            s1 = random.randint(1, ns)
            s2 = random.randint(1, ns)
            if s1 != s2 and (s1, s2) not in existing_routes and (s2, s1) not in existing_routes:
                existing_routes.add((s1, s2))
                d = random.randint(1, 100)
                routes.append((s1, s2, d))
                break
    
    test_case = []
    test_case.append(f"{ns} {nl}")
    for s1, s2, d in routes:
        test_case.append(f"{s1} {s2} {d}")
    
    return '\n'.join(test_case)

# Generate a sample test case
print(tcgen())
```

This function generates values for `ns` and `nl` within the given constraints. It ensures that the routes are between different stations and without duplicates by keeping track of existing routes using a set. The distance `d` for each route is also randomly generated within a typical range (1 to 100). Finally, it formats the test case as specified and returns it as a string.

This is an example output from running the `tcgen` function:

```
7 13
1 3 12
1 4 57
2 5 43
1 2 8
3 5 67
6 1 23
2 4 78
4 3 24
7 5 34
6 4 90
7 3 53
5 6 18
4 7 27
```

You can run and adapt this function as needed to generate different test cases for your problem.