The reason is, first, the increasing number of private cars, road traffic increased, traffic interleaving point and the point of conflict increased risk of accidents increases;

究其原因，一是私家车数量剧增，路面交通流量加大，交通交织点和冲突点增多，发生事故几率增大；

youdao

Increased traffic necessitated widening the road.

交通量增大，这就需要拓宽道路。

《牛津词典》

In contrast, research has clearly shown an increased risk of road traffic injuries when drivers use mobile phones (either handheld or "hands-free") while driving.

相反，研究结果却清楚地表明，由于驾驶员驾车时使用移动电话(无论是手持还是“免提”)，发生道路交通伤害的危险会加大。

youdao

People living near a road junction in the Cotswolds say a new roundabout and set of road signs have led to increased levels of traffic.

BBC: Road signs row in the Cotswolds

Campaigners argued the sites would not be able to cope with such a population rise and the road networks would become clogged with the increased traffic.

BBC: Wokingham borough blueprint for 10,000 homes agreed

He said they were unable to sit outside their homes due to traffic pollution and their lives had been transformed as use of the road had increased.

BBC: Google