
    Write a function that converts delivery route identifiers from the legacy tracking system's snake_case format to the new fleet management system's camelCase format, ensuring seamless integration between traffic monitoring and weather alert modules. The function must handle route codes containing multiple underscores and maintain the first word in lowercase while capitalizing the first letter of subsequent words.
    

    
import re

def snake_to_camel(word):
    """
    Write a function that converts delivery route identifiers from the legacy tracking system's snake_case format to the new fleet management system's camelCase format, ensuring seamless integration between traffic monitoring and weather alert modules. The function must handle route codes containing multiple underscores and maintain the first word in lowercase while capitalizing the first letter of subsequent words.
    

    """
import re

def snake_to_camel(word):
    """
    Write a function that converts delivery route identifiers from the legacy tracking system's snake_case format to the new fleet management system's camelCase format, ensuring seamless integration between traffic monitoring and weather alert modules. The function must handle route codes containing multiple underscores and maintain the first word in lowercase while capitalizing the first letter of subsequent words.
    

    """
    return ''.join((x.capitalize() or '_' for x in word.split('_')))