The INS/GPS integrated vehicular navigation system provides superior performance in comparison with either a stand-alone GPS or INS as it can overcome each of their individual limitations. For navigation purpose, such a system can bridge the gap caused by GPS signal blockages and provide seamless navigation solutions in GPS denied environments. However, since the quality of the INS sensors used for land vehicular navigation is relatively poor compared with those expensive ones used for mapping applications, the sustainability of such low cost INS/GPS integrated navigation systems is limited by their positioning errors accumulate rapidly with time during GPS signal blockages. Therefore, this article proposes a novel algorithm that embeds a map matching algorithm in a loosely coupled INS/GPS integration scheme. One of the MM methods, the Near Feature Search, is chosen in this study because of simplicity. When GPS signal becomes unavailable, map derived information using EKF estimated states substitutes the original GPS update mode in main EKF. In other words, this algorithm uses map derived information to provide continuous update to avoid positional error accumulation during GPS signal blockages. On the other hand, GPS positions are used with MM when more than four GPS satellites are available to update the main EKF. In principle, a loosely coupled INS/GPS integration system with proposed algorithm can provide sufficient sustainability for land vehicular navigation applications in GPS denied environments. However, the horizontal 2D map matching algorithms booming these days are unable to deal with the cases of viaducts in many burgeoning urban areas that focusing on the transport development such as elevated highway, Mass Rapid Transit (MRT) system or other highway needed transportation systems. The height components become an essential component for ongoing 3D GIS based land vehicular system. In this study, a 3D Map Matching (MM) algorithm is embedded to current INS/GPS fusion algorithm for enhancing the sustainability and accuracy of INS/GPS integration systems. The proposed algorithms are verified by using the field test collected in GPS denied environments. The preliminary results demonstrate that the map embedded loosely coupled INS/GPS integration scheme does improve the performance of the MEMS INS/GPS integrated navigation system applied by limiting the positional errors accumulation during frequent GPS signal blockages.