It replaces the antiquated three @-@ level , modified cloverleaf interchange built in the 1960s that caused a severe bottleneck by narrowing US 75 down to two lanes at the junction of the two highways . The looped ramps of the cloverleaf forced motorists to slow down drastically , backing up traffic . Left @-@ hand exits contributed to the congestion . Further , its two frontage roads were not directly connected to each other , making local access difficult .