We suspect that the reconstruction of the roads, which has been discussed upon over the past several years, may impede the traffic and result in a detrimental effect on the whole network. 聼起來自然嗎?

I personally would say:

We suspect that the reconstruction of the roads, which has been discussed upon (Or debated about) over many years, may have a detrimental effect on traffic.

Or , with your example, you could say;

...may impede traffic and have a detrimental effect on the whole network.