Interesting idea and compositionally it's fine. I think the minute exposure was a bit too long and is spoiling the main purpose, the light streaks. There are so many streaks here they look like the cars were being driven by drunk drivers and possibly a collision halfway up the road! The exposure is so long that the whole of the road is brightly lit as well instead of seeing a nice contrast between the light streaks and the darker road behind it.
Light streaks really do take a lot of 'playing' to get right but I think you've got the general idea going fine, just needs a bit more experimentation to get the balance right so that the image hangs together well. I am assuming the aperture was very narrow here in order to get good depth of field as the sky is surprisingly dark for such a long exposure.
Did you take any others that night Tin? Be interesting to see what else you came up with. I agree with your own thought that a shot taken purely for the clock face that could have been brought in would have helped. I agree that relatively reduced post-pro is ideal but when you are working with such unbalanced lighting, you are rather giving yourself too many disadvantages to overcome. The clock tower itself is a bit bright but the top of the clock tower is very dark so again balancing the two really would be better with a composite.
That's a good location and I assume you live nearby (not sure where it is myself but I am sure the Scots among us will recognise it) so get back up the ladder and see what else you can pull out
Cheers,
Rob