Traffic congestion on local roads is costing West Midlands companies "billions", with many reporting rising operating costs, a report suggests.
More than 60% of firms said public transport was not a viable option
Almost 90% of firms had seen operating costs "shoot up" because of congestion, according to a Confederation of West Midlands Chambers of Commerce survey.
Another 45% of the 381 companies questioned said they had lost business as a result of the problem.
The morning school run and volume of traffic were seen as the main reasons.
Many of those surveyed believed these were the main reasons behind delays on A roads, trunk roads and motorways.
David Burton, confederation chairman, said: "The region's businesses continue to be heavily reliant on the road network, but congestion and delays are costing them billions of pounds a year.
"They need reliable and predictable journey times for the movement of people and goods but they are not getting that from the roads or from public transport and it is a problem that will only get worse unless drastic measures are taken."
The confederation said its survey suggested 85% of West Midlands firms were "heavily reliant" on the road network compared to a national average of 75%.
More than 60% of firms surveyed did not perceive public transport to be a viable alternative, while 94% called for immediate investment in it.
However, eight out of 10 firms said if reliability and punctuality improved, they would use public transport more often.
And nearly 70% said cheaper fares and better discounts would also persuade them to use buses and trains for their business.
The confederation brings together seven chambers of commerce from across the region.