56 Continental J. Engineering Sciences 3: 56 - 63, 2008 ©Wilolud Online Journals, 2008. A MICROCONTROLLER-BASED HIGHWAY-RAILWAY LEVEL CROSSING TRAFFIC CONTROLLER J. A. Enokela 1 and E.J. Ibanga 2 1 Department of Electrical Engineering, University of Agriculture, P.M.B 1273, Makurdi, Nigeria 2 Department of Physics, Nasarawa State University, P. M. B. 1022, Keffi, Nigeria. ABSTRACT Highway-railway level crossings across the country have witnessed a number of fatal accidents in the past. Many of the level crossings in the rural areas are not protected by level crossing gate signals. In the urban areas where these provisions are put in place, the operation of the level crossing gate is usually entrusted to the level crossing keeper- who opens and closes the gate against road traffic at times that he deems necessary. This results in the closing and opening of the gate earlier or later than necessary as well as the intervention of a human superintendent who may not be on duty at the correct time. These factors cause difficulties and possible accidents for the highway/railway users. This work describes a control system that uses a microcontroller to handle traffic flow across a major and typical highway-railway level crossing located in an urban centre. It is seen that the incorporation of computer methods into the operation of the level crossing improves its safety, speed and reliability. KEYWORDS: Highway, Railway, level crossing, control, traffic, microcontroller, INTRODUCTION Highway-Railway level crossing traffic signal controls in the country have traditionally been operated by level crossing keepers who use flags and signal lamps mounted on gates to warn highway users of the approach of a train. These keepers, on sighting a train, physically close the railway gate against road traffic until the train has passed after which the gate is opened (Nigerian Railway Corporation: General Rules, 1979) . This traditional method is very much dependent on the human factor and has important shortcomings: (i) There is no preemption in the system to alert the highway users of the approach of a train before the railway gate is closed against the road traffic. (ii) The gate is generally closed against road traffic for a longer period than absolutely necessary to secure the safety of the public and train. (iii) The entire operation depends on the level crossing keeper who may not show up for his duty on time as has been known to happen especially in poor weather conditions. These shortcomings have led to lots of inconvenience for both the railway and highway users as well as the occurrence of accidents on such level crossings. Traffic controls at level crossings are generally required to have some form of preemption. This is the transfer from normal operations of signals to a special control mode. Rail traffic preemption often occurs when a train approaches highway-rail grade crossings (Metrolinks Ttrain, 2004 and Institute of Transport Engineers, 2004). Preemption defines various times and these include: (a) Advanced Preemption time which is the notification of an approaching train that is forwarded to the highway traffic signal controller unit for a period of time prior to activating the railway active warning devices. (b) Pedestrian Clearance time is the time provided for a pedestrian crossing on a crosswalk after leaving the curb or shoulder, to travel to the centre of the farthest traveled lane or to a median. At a normal walking speed of at least 1.2m/s the walk interval should be at least 7 seconds.