Cambridge has quite a crappy road system for a city, so any significant roadworks seem more likely to have impact on a high number of road users.

For contrast, look at the Milton Keynes grid-road system, where people route around such inconveniences very easily.

I don't think Cambridge has much in the way of equal-cost alternative routes to most destinations, from my memories of driving and riding (a motorbike) there. There's usually only one obvious way to get somewhere.

From my knowledge of Cambridge there are generally zero good routes to take a car. It is part of the conspiracy to make everyone cycle.