The sub-project CK237 of the Xinzhuang line's section contract CK570B project contains two tube tunnels each over 900 meters long. For the purpose of fending the group of the load bearing foundation pipes under the depth of 30 meters of the Kuanghwa Bridge on the Xinsheng S. Rd., the two tube tunnels are approximately 20 meters in depth under the ground and should be located on either side of Kuanghwa Bridge. The distance between them is around 24 meters. To construct a connecting escape tunnel between the two long tunnels, due to restrictions created by the structure of the Kuanghwa Bridge, the cross passage location can only be positioned under Lane 25 of Songjiang Rd. where a traffic lane for cars to make a U-turn is located in a culvert below the Kuanghwa Bridge. Based on the above reasons, the length of the cross passage is extremely long. High pressure grouting improvements were performed before the excavation of the cross passage, the execution of which was performed under difficult conditions in a 4-meter-high and 13-meter-wide culvert approximately 35 meters underground. Finally, this highly difficult work and all dangerous factors which include the grouting improvement, the cross passage excavation, water test before the excavation, and the safety gate of the cross passage, have been overcome and completed on schedule by the wholly domestic participants.