Traffic congestion has many effects. One of the most important is parking problems. People find it difficult to park their cars especially in the city center. Long delays in getting to and from work are another result, leading to less productivity from employees. There are also more accidents, because people become frustrated or angry due to the traffic jams. Pollution in the city center worsens as a result of car emissions, and the city becomes a less attractive place to live. Shops are forced to close in the city center and have to relocate to malls or to the outskirts of the city, where parking is available.