A fire in road tunnel can be dangerous and lead to serious consequences if not addressed appropriately. In a tunnel fire incident, creating a smoke free path for motorist evacuation and facilitating fire fighters to access the fire is critical for fire and rescue operations. A means of achieving this is to use ventilation fans to blow sufficient air down the tunnel ensuring no back-layering of smoke occurs upstream of the fire. The airflow necessary for such operation is known as the critical velocity which is a function of a number of factors includes; heat release rate, tunnel geometry, tunnel gradient etc. Among these parameters, the heat release rate is the most difficult to identify as this value is dependent on the types of vehicles, number of vehicles involved, the type of cargo and the quantity of cargo carried by these vehicles. There are also other factors such as the influence of ventilation condition, tunnel geometry and the use of legislation (to restrict hazardous vehicles entering in tunnel) that could affect the heat release rate in a tunnel fire. The number of possible fire scenarios is numerous. Based on current practise, fire size selection for most tunnel ventilation design often references various guidelines such as NFPA 502, BD78/99 or the PIARC technical committee report. The heat release rate, particularly for goods vehicle recommended by the guidelines varies from 20 to 30 MW. However, recent fire tests conducted in the Runehamar tunnel experiments indicate a higher heat release rate. These experiments suggest that heat release rate guidelines for goods vehicles might be underestimated. An ideal means to estimate the heat release rate in the tunnel is to use the oxygen consumption calorimetry technique. However, this approach is generally expensive, logistically complicated to perform and it is often not feasible to conduct such tests for a tunnel project at the initial design stage simply because the structure and systems are not ready for such activities. This research thesis presents an approach to establish a design fire in a road tunnel particularly the peak heat release rate for emergency tunnel ventilation system design. The analysis consists of two stages; stage one involves the use of a probabilistic approach (risk analysis) to identify the potential cause and type of vehicle which could result in a tunnel fire. Findings from the risk analysis are used in stage two in which Computational Fluid II Dynamics (CDF) modelling is used to establish the heat release rate in the tunnel considering factors such as fuel load, ventilation condition, tunnel geometry and ignition location. The Fire Dynamics Simulator (FDS 4.0.7), a CFD model of fire-driven fluid flow is used for the analysis and an urban road tunnel project in Singapore is used to illustrate this methodology. Other topic related to this research work includes the reconstruction for the Runehamar tunnel fire test using numerical approach to calibrate the FDS simulation model. The used of Probabilistic Bayesian approach and CFD approach using FDS to estimate the heat release rate in the tunnel is also investigated in this thesis. The effect of vehicle fire spread in road tunnel and numerical simulation of road tunnel fires using parallel processing is presented. Preliminary work in using FDS5 for tunnel simulation work is discussed as part of the research work in this project.

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Thermal mapping, the measurement of road surface temperatures (RSTs) with an infra-red thermometer (IRT) mounted in a moving vehicle, seeks to identify a 'characteristic and repeatable' thermal fingerprint (temperature profile) for any stretch of road. A number of uses have been suggested for the process, including ice detection sensor network design and identifying stretches of road for selective gritting, with potential financial and environmental benefits due to reduced salt usage. The project 'Thermal Mapping for a Highway Gritting Network' has resulted in the most extensive survey yet undertaken. The aims were to investigate the reliability/repeatability of fingerprints and establish confidence limits. Comprehensive mapping of Sheffield roads took place during winters 1988/89- 1991/92. Significant errors (+/-3°C) in RST readings were identified after the first winter. Laboratory and road tests confirmed errors were produced due to warming/cooling of the IRT. Operating the IRT in a temperature control box eliminated these errors. Seven Sheffield routes were mapped during winters 89/90 and 90/91 with route 1 fingerprints (100) used for most of the analysis. The main factors affecting the variation in RSTs were confirmed as altitude and land-use with localised peaks occurring under bridges and by trees and tall buildings. The occurrence of cold air drainage on clear/calm (extreme') nights resulted in 'low' RSTs at relatively low altitudes. Differences were identified between what should have been identical extreme fingerprints. These were related to variations in the behaviour of cold air drainage. rom night to night and variations in wind direction/speed interacting with local relief. Confidence limits for extreme fingerprints and maps, taking into account possible errors in mapping and differences between fingerprints, were +/-20C and +/- 2.5°C respectively. With important decisions concerning gritting made when RSTs are +/-5°C confidence limits of this magnitude have important implications for thermal mapping. Future use should be restricted to sensor network design and assessment/re-design of gritting network.

Microclimates of various road weather stations in Devon were examined. Road surface temperatures were measured during various synoptic conditions. Data from the thermal mapping exercise conducted by Vaisala TMI were analysed and categorised as clear and calm, cloudy and windy, and a condition between the two extremes. Results indicate valleys to be relative cold spots in clear conditions, and high altitude stations are cold spots during cloudy conditions. A separate case study during the cold spell of February 1991 reinforced the conclusion and extended these views county wide. Coastal stations with surface winds were observed to be 1 to 3 deg.C warmer than inland stations. Reaction times, the delay in road temperature reaction due to synoptic change, showed for the most difficult forecasting scenario on the passage of a cold front, small reaction times (less than 30 minutes) at exposed sites when clear skies resulted, sheltered sites having a reaction time of up to 2 hours. Sheltered sites in valleys had the largest temperature drop due to cold air drainage. A surface climate model was used in retrospect to predict road surface temperatures at night, each station having its own characteristic exposure. Cloud change was estimated from satellite images. Results indicate predicted minimum temperature within 0.5 deg.C of observation. Real time forecasts were tried and an accuracy of 65% at this level was achieved. These results were equal or better than the existing "Open Road" forecasts.

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