Bell Atlantic plans to begin construction of a data-packet-switched, long-distance network for the East Coast in July. As part of the planned network, the phone company has signed a $200 million contract with Lucent Technologies in Murray Hill, N.J., to supply components and to integrate several of the network's systems. Bell Atlantic estimates that the market for data services in the region will double and possibly triple to $80 billion to $90 billion a year by 2003. The company estimates it will generate more than $3 billion a year in new revenue from long-distance transport services over the network. It expects value-added platform and application services to generate an additional $2 billion to $3 billion in yearly revenues.