A problem of building one route at a time is usually that the routes generated in the latter part of the process are of poor quality as the last unrouted customers tends to be scattered
over the geographic area. In Potvin and Rousseau (1993) tries to overcome this problem of the insertion heuristics by building several routes simultaneously. The initialization of the
routes is done by using the insertion heuristic of Solomon (1987). On each route the customer farthest away from the depot is selected as a seed customer. Then we proceed by computing the best feasible insertion place for each unserviced customer and insert the one with the largest difference between the best and the second best insertion place. This method is better than the Solomon heuristics but still the solutions are quite far away from optimum. In Russell (1995) elaborates further on the insertion approach.